# Evolution of competitive ability in multispecies bacterial communities is sensitive to community composition (51942)

**Tarmo Ketola**, Lauri Mikonranta, Jouni Laakso, Johanna Mappes.

*University of Jyvaskyla; University of Helsinki.*

Very few studies have experimentally assessed the evolutionary effects of species interactions within the same trophic level. In such communities, the need for fast exploitation of resources could drive the evolution of increased resource competition and growth rate. Accordingly, when Serratia marcescens bacteria evolved in 20 different four species communities, their growth rate exceeded the growth rate of the clones that had evolved alone. In addition to the community effects the existence of key species that control much of the community's functionality is often emphasized in the ecological literature. Here we show experimentally that some species can also strongly affect the evolutionary effects in communities where all the members occupy the same trophic level. This result shows that evolution can lead to vastly different outcomes depending on the community structure, which could complicate prediction of consequences environmental changes on species living in multispecies communities.

Session 2 MON POL C 14

# The role of dispersal and interspecific competition on local adaptation (52045)

**Dries Bonte**, Karen Bisschop, Rampal S. Etienne, Dries Bonte.

*Ghent University; University of Groningen.*

Besides selection, biological interactions and non-selective forces can influence the rate at which a species can adapt to a new habitat. However, experimental evidence is usually scarce. Here, using experimental evolution we investigate the role of dispersal and interspecific competition on the rate to which the spider mite (Tetranychus urticae) can adapt to a new host plant. Additionally, we test whether an increase in adaptation leads to an increase in competitive ability. Our results show a humpback shaped relation between dispersal and adaptation and a negative impact of competition on adaptation. We also show that populations that adapt to a new host without the presence of a competitor increase their competitive abilities when later exposed to competition.

Session 2 MON POL C 14

# Rescued by evolution - problems ahead: Adapting to fluctuating environment increases invasiveness (52169)

**Kati Saarinen.**

*University of Jyväskylä.*
Evolving in a disturbed environment might select for traits that promote invasiveness; rapid population growth, plasticity and persistence. Disturbed and heterogeneous environments might also be more prone to invasions than non-disturbed. These are interesting theories especially now, when the climate change causes increasing amounts of disturbances. These timely ideas were put into practice in an experiment utilizing Serratia marcescens bacterial strains evolved for 2.5 months at rapidly fluctuating or constant temperature, and by following S. marcescens invasion success to bacterial communities under thermal fluctuations or under constant temperature. We found very clear evidence that the fluctuation adapted strains had evolved a better ability to invade bacterial communities than the ones from the constant environment. This phenomenon got even more pronounced as invasion proceeded further. Moreover, thermal fluctuations during invasions clearly promoted the invasion. It is ironic that the very same strains that had avoided extinction by evolution, evolved to become more invasive. Thus, climate change induced environmental fluctuations do not only impose threat on biota by driving species extinct. If species can evolve ways to cope fluctuations, evolutionary rescue can also lead to the emergence of invasive genotypes - pests and pathogens.

# Life after death: The fate of the microbiota of a dying host (52493)

**David Preiswerk**, Jean-Claude Walser, Dieter Ebert.

*Zoological Institute, University of Basel; Genetic Diversity Centre (GDC), ETH Zürich.*

From a microbial perspective living organisms represent dynamic, transient ecosystems. The transition of a living host to dead organic matter implies profound changes in habitat properties which will find expression in microbiota composition. The microbiota dynamics before and beyond host death can in turn shed light on lifestyle and ecology of the respective microbes.

We examined the temporal dynamics of the microbiota of the planktonic crustacean Daphnia magna through 16S amplicon Illumina MiSeq sequencing. Conventional clonal animals were starved to death under axenic conditions and left for four days of decomposition. Over the entire timeframe samples were collected in 12 hourly intervals.

We found strong temporal dynamics in microbiota composition. Most prominently the genera Limnohabitans and Rubrivivax (both Betaproteobacteria) increased during starvation but decreased strongly towards and after host death. Pseudomonas (Gammaporteobacteria) and Rhodobacter (Alphaproteobacteria) however only appeared before host death and increased strongly during decomposition. These results suggest an important, unexplored role of the dead host in microbiota ecology. For opportunistic bacteria the strategy to persist in the living host and subsequently exploit its remains for efficient proliferation could be very successful. The decaying host would thus act as an environmental reservoir for colonization of novel hosts.
# The effect of interspecific competition on the evolutionary response of photosynthetic algae to elevated CO2 (52706)

**Diane Lawrence**, Sinéad Collins.

*University of Edinburgh.*

Species' evolutionary responses to novel environments are often shaped by biotic interactions such as predation and competition. Experimental work has demonstrated that in some cases competitive pressures may push adaptation to proceed more quickly but also that competition may hinder adaptation, for example, due to trade-offs. Here we ask what the evolutionary consequences of interspecific competition are when the initial growth response to the novel environment is positive, as will often be the case with photosynthetic species in acidifying oceans. We tested the prediction that interactions between species would inhibit adaptation to elevated CO2 using experimental evolution with the marine algae Ostreococcus. We selected 6 Ostreococcus lineages for approximately 200 generations in monoculture and in cocultures at average pCO2 of 430µatm and 1000µatm in fluctuating and stable CO2 regimes. Here we discuss the evolutionary response to elevated CO2, the impact of species interactions on adaptation to elevated CO2 and the effect that interspecific competition during evolution had on the capacity of the organisms to respond to further abiotic and biotic changes. The results of this experiment will contribute to our understanding of the impacts that biotic interactions have on species adaptation to favourable novel environments.

# The interaction of Saccharomyces paradoxus with its natural competitors on oak bark (52807)

**Vienna Kowallik**, Duncan Greig.

*Max Planck Institute for Evolutionary Biology, Plön, Germany; Department of Genetics, Evolution, and Environment, University College London, London, UK.*

We studied the ecology and interactions of Saccharomyces paradoxus, the closest related species of the model organism S. cerevisiae, in natural oak bark medium. In nature, S. paradoxus is often found on oak trees but it is unclear whether the yeast's association with oaks is an artifact of biased sampling methods or whether it is adapted to this habitat. We show that S. paradoxus grows surprisingly well on sterilized oak bark medium, but its growth is largely suppressed by the oak bark community in nonsterilized oak bark. We cultured and identified a set of twelve common fungal and bacterial species from oak. High-throughput DNA sequencing of oak bark samples verified that these microbes were representative of the oak microbial community. We then tested how each of the twelve microorganisms affected the growth of S. paradoxus in direct competition in oak bark medium at temperatures representing summer and winter conditions. We identified positive and negative interactions: one Pseudomonas species produced a diffusible toxin that killed S. paradoxus, whereas a Mucilaginibacter species had the opposite effect and facilitated S. paradoxus' growth. Further experiments indicated a mutualistic interaction between these two species that was only apparent in the complex, natural medium.
# Bias in the Heritability of Preference and its Potential Impact on the Evolution of Mate Choice (51734)

**Derek Roff**, Daphne Fairbairn.

*University of California; University of California.*

The evolution of mate choice is a function of the heritability of preference. Estimation in the laboratory is typically made by presenting a female with a limited number of males. We show that such an approach produces a downwardly biased estimate, which we term the heritability of choice. Because females in the wild typically survey on average less than 5 males we argue that the heritability of choice may be more meaningful than the heritability of preference. The restricted number of males surveyed can lead to a reduction in the phenotypic variance of the preferred trait in the group of males selected by the females if the phenotypic variance in preference is equal to or less than the phenotypic variance in the referred trait. If the phenotypic variance in preference exceeds that of the preferred trait the opposite occurs. A second effect of the restricted number of males sampled is that females are likely to mate initially with males that are not the most preferred. The failure to find the most preferred male may account for the common observation of multiple matings and extra-pair copulations. We suggest that current explanations for polyandry need to take this failure into account.

# Heritability of heterozygosity leads to transgenerational effects of heterozygosity and inbreeding (51802)

**Pirmin Nietlisbach**, Lukas Keller, Erik Postma.

*University of Zurich.*

Although many studies have shown that heterozygosity is subject to natural and sexual selection, its response to selection is rarely considered. Indeed, despite the fact that heterozygosity has previously been shown to be heritable whenever allele frequencies are unequal, this mathematical inevitability remains largely unknown. Furthermore, quantitative predictions of heritability of heterozygosity have so far only been possible for bi-allelic loci. Here we use newly developed theory for multi-allelic loci, as well as a long-term individual-based dataset and 160 microsatellite markers for an island population of song sparrows (Melospiza melodia) to show that the empirically estimated heritability of heterozygosity of 0.31 closely matches our theoretical predictions. Combined with a correlation between heterozygosity and fitness, this allows for a response to selection of heterozygosity. Additionally, because heterozygosity is heritable, the heterozygosity of descendants of inbred individuals will be reduced, irrespective of their own inbreeding level. In line with this, we show that ancestral inbreeding is a predictor of heterozygosity in song sparrows. Interestingly, this effect is expected to have fitness consequences that may confound those of purging. In
conclusion, heterozygosity being a heritable trait allows for a response to selection, and for transgenerational fitness consequences of inbreeding and heterozygosity.

# Genetic compatibility underlies benefits of mate choice in an external fertilizer (52053)

**J. David Aguirre**, Mark W. Blows, Dustin J. Marshall.

*Massey University; University of Queensland; Monash University.*

Mate choice is a universal feature of sexually-reproducing species. In species with external fertilization however, direct interactions between reproductive partners are dramatically reduced and instead, mate recognition and choice typically occur at the level of gametes. Here, we examine the mechanisms underlying the benefits of gamete-level mate-choice (GMC) for paternal quality or compatibility in an externally fertilizing ascidian in the field. A manipulative mate-choice assay confirmed that offspring viability was greater in clutches where we allowed GMC relative to clutches where we precluded GMC. Additionally, we demonstrated that these benefits of GMC were driven by sexual selection rather than ecological genetic diversity effects, and that sexual selection was strongest during the early life-cycle stages. Subsequent quantitative genetic experiments revealed that paternal quality effects on offspring viability were generally weaker than parental compatibility effects, and that there was significantly more variation in parental compatibility for the trait combination underlying the benefits GMC. Overall, we provide evidence suggesting that the most compatible combinations of gametes produced the greatest number of viable offspring, and therefore that mate choice for genetic compatibility enhanced reproductive success in the field for a species where mate choice occurs predominantly among gametes.

# The structure of the mating network as a framework to understand mating systems: theory and tests (52251)

**Grant McDonald**, Lewis Spurgin, Eleanor Fairfield, David Richardson, Tommaso Pizzari.

*University of Oxford; University of Groningen; University of East Anglia; University of East Anglia; University of Oxford.*

Multiple mating by females (polyandry) is a key component of mating systems, influencing the opportunity for both pre- and post-copulatory sexual selection on males. Yet empirical studies have provided conflicting results for the way polyandry impacts the operation of sexual selection. Recent work suggests that this may be further complicated by the relationship between male promiscuity and that of his partners (“mating structure”) which determines the reproductive value of male mating success. Reconciling conflicting empirical results across systems, requires: i) predictions for the effects of polyandry and mating
structure on sexual selection under biologically meaningful scenarios, and ii) empirical investigations to test predictions under realistic conditions. Here, we first use a simulation approach to predict the effects of polyandry and mating structure on the operation of pre- and post-copulatory sexual selection. We then employ an experimental approach using Red junglefowl (Gallus gallus) to test such predictions, and demonstrate how polyandry and mating structure combine to shape the operation of pre- and post-copulatory sexual selection. This study provides a framework to understand the response of sexual selection to variation in polyandry across mating systems and reveal the subtle yet powerful role of mating structure in modulating the influence of polyandry.

## The breakdown of self-incompatibility during a range expansion (52406)

**Francisco Encinas-Viso, John Pannell, Andrew Young.**

*CSIRO; University of Lausanne.*

It is commonly observed that for species that vary in their mating system among populations, range margins are enriched for increased selfing rates. This has often been attributed to a response to selection under mate and/or pollinator limitation. However, previous theoretical studies have shown that a reduction of inbreeding depression could facilitate the breakdown of self-incompatibility (SI) and therefore the invasion of self-compatibility (SC); we might thus expect that, during a range expansion SC could be favoured by selection in populations in which inbreeding depression has been purged. Here, we present results from a spatially explicit individual-based simulation model of a 2-dimensional range expansion, in which both inbreeding depression and the number of S-alleles at an SI locus can evolve, and in which there are recurrent mutations to SC. We find that under certain conditions (low recombination and migration rates), SC evolves and completely displace SI. Under other conditions, SC and SI are able to coexist in the expanded metapopulation, with spatial segregation of SC and SI populations. Importantly, our results indicate that evolution of inbreeding depression during a range expansion can be entirely sufficient for the evolution of SC at range margins, and that mate or pollinator limitation is not necessary.

## The intersection of the mating system and strong selection: herbicide resistance is related to increased inbreeding in Ipomoea purpurea, the common morning glory (52523)

**Regina Baucom, Adam Kuester, Shu-Mei Chang.**

*University of Michigan; University of Georgia.*

Human-mediated influences on plant mating systems can lead to significant ecological and evolutionary outcomes for plant populations. While it has been shown that increased
inbreeding is associated with habitat fragmentation, the influence of strong selective agents, such as herbicide, on plant mating is rarely considered. Here we examine the potential that the evolution of resistance to glyphosate, which is the main ingredient in the widely used herbicide RoundUp, has influenced the mating system of Ipomoea purpurea, the common morning glory, a species of agricultural weed that employs a mixed mating system. Using a progeny array of replicate maternal lines sampled from 23 populations collected in the US, and a greenhouse resistance assay, we uncovered a significant positive correlation (r = 0.53; P < 0.008) between estimates of the selfing rate (F) and the level of herbicide resistance. We hypothesize there are two potential explanations for this result: first, demographic changes following herbicide exposure may lead to greater self-fertilization and/or sib-mating in resistant populations; second, evolutionary changes in the mating system may occur concomitant to the evolution of increased resistance. Our results are broadly relevant to organisms with labile mating systems subjected to strong selective forces.

# Inherited Inbreeding: evidence of sex-specific, additive genetic variances in the degree of inbreeding (52592)

Matthew Wolak, Pirmin Nietlisbach, Lukas Keller, Peter Arcese, Jane Reid.

University of Aberdeen; University of Zurich; University of British Columbia.

Inbreeding has the potential to profoundly shape mating system evolution. A pervasive assumption in evolutionary theory is that the degree to which individuals inbreed will evolve in response to selection stemming from inbreeding depression. Such evolutionary response requires non-zero additive genetic variance in the degree of inbreeding, but this has never been tested. We developed a novel analysis that facilitates estimation of additive genetic variance in the degree of inbreeding and applied this to long-term data from a free-living song sparrow population. Specifically, we estimated female- and male-specific genetic variances contributing to variance in the kinship between socially-paired mates, while simultaneously estimating effects of immigration and of each individual's own coefficient of inbreeding on the mean kinship between mates. Female and male additive genetic variances in the kinship between mates both exceeded zero and the cross-sex genetic correlation was close to one, meaning that there was substantial total additive genetic variance in the degree of inbreeding. Effects of immigration and of each individual's coefficient of inbreeding on the kinship between mates were negative and positive respectively. We provide the first evidence that the degree of inbreeding shows additive genetic variance in nature and might consequently evolve in response to selection.

# Recombination rate variation and differential gene flow shape the genomic landscape of speciation in sea bass (52219)

Pierre-Alexandre Gagnaire, Nicolas Bierne, François Bonhomme.
The genomic landscape of species divergence provides a static picture of the dynamic process of speciation. Therefore, reconstructing the history of speciation is fundamental to understand how this picture captures the complex interplay between migration, recombination and selection as speciation unfolds. Here, we combine RAD-sequencing in natural populations and whole-genome sequencing in mother-father-child trios to investigate patterns of genome-wide divergence between naturally hybridizing lineages of Atlantic and Mediterranean sea bass (Dicentrarchus labrax). We find that variation in local recombination rates influences both nucleotide diversity within lineages and differentiation between lineages. Genomic islands of differentiation map disproportionately to low-recombining regions of reduced diversity, but some are also found in regions of high diversity and high recombination rates. Fitting alternative demographic models that explicitly account for genomic variation in demographic parameters revealed that the genomic landscape of divergence between sea bass lineages was generated both by selection at linked sites during divergence and varying rates of introgression across the genome after secondary contact. Therefore, genomic islands in sea bass are not simply an incidental consequence of reduced diversity in low-recombining regions, but also the product of reduced gene flow in these regions.

# The repeatability of genomic architecture in a homoploid hybrid species (52266)

**Anna Runemark**, Cassandra N. Trier, Fabrice Eroukhmanoff, Jo S. Hermansen, Tore O. Elgvin, Glenn-Peter Saetre.

The genomic revolution suggests a more important role for hybridization and introgression in speciation than has previously been recognized. The potential of hybridization to form novel variation depends on whether different genomic mosaics can arise, or if only certain combinations are viable. To investigate the creative potential of hybridization we re-sequence the whole genomes of three island populations of the homoploid hybrid Italian sparrow Passer italicae, which appear to result from three independent hybridization events. First, we investigate whether the hybridization events are independent by examining if genetic material inherited from the respective parent species on Crete, Corsica and Sicily originate from different parent populations, and whether the proportion of the genome inherited from the parent species and the size and distribution of genomic areas from the parent species differ between these islands. Then, we investigate whether the same genomic regions are more frequently inherited from the same parent species than expected by chance, genome wide, for coding genes only, and for specific gene classes. Finally, we investigate whether recombination frequency distribution and estimated time of hybridization differ between islands. Our study system provides a rare opportunity to investigate the creative potential of – and the genomic landscapes resulting from – hybridization.
# The genomic landscape of the speciation continuum in the killer whale (52440)

**Andrew D. Foote**, Nagarjun Vijay, María C. Ávila-Arcos, Matteo Fumagalli, Thorfinn Sand Korneliussen, Michael D. Martin, Philip A. Morin, M. Thomas P. Gilbert, Jochen B. W. Wolf.

*Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden; Centre for GeoGenetics, Natural History Museum, University of Copenhagen, Copenhagen, Denmark; Department of Integrative Biology, University of California, Berkeley, USA; Southwest Fisheries Science Center, La Jolla, USA.*

To better understand the progression and chronology of adaptation and reproductive isolation during the early stages of speciation we sequenced 49 genomes and analysed whole-genome divergence between pairs of killer whale Orcinus orca ecotypes, which we demonstrate fall along the speciation continuum. The study system provides a useful comparison to genomic evolution in hominins, given the similar life histories, and the role of gene-culture coevolution in a recent, rapid radiation to a global distribution. We find that genetic diversity is lost through population splits and founder effects and the subsequent formation of reproductive isolation. This combined with subsequent population expansion has facilitated rapid shifts in allele frequencies and therefore the build up of genomic differentiation through stochastic processes (drift) and selection. We find outlier regions containing significantly differentiated SNPs in exons and potential regulatory regions in all pairwise comparisons. GO analyses suggest links to local adaptation, for example due to differences between fish- and mammal-eating ecotypes, or climate differences. We compare genome-wide estimates of Fst with Dxy and find a negative correlation, which we argue suggests that reproductive isolation has developed first, followed by the build up of heterogeneous differentiation, in-part due to heterogeneous levels of selection across the genome.

# What causes "genomic islands" of excess Fst ? (52460)

**Nick Barton**, Hugo Tavares, David Field.

*IST Austria; John Innes Institute; IST Austria.*

Genes responsible for adaptation and for reproductive isolation may be identified by local increases in Fst along the genome. However, such "genomic islands" may be produced in two ways: through gene flow, which prevents or erases divergence everywhere except close to loci that are kept different by divergent selection, or by processes such as background selection or selective sweeps, which reduce diversity within populations, and hence increase Fst. I compare these different scenarios, and show that while selective sweeps can produce sharp "islands", gene flow tends to produce broad "islands", especially around clusters of selected loci. These theoretical arguments are illustrated by the Antirrhinum flower colour hybrid zone, where two closely linked loci determine sharp clines in flower colour
# Recombination rate and the chromosomal distribution of gene flow between species of Heliconius buterflies (52752)

**Simon Martin**, John Davey, Chris Jiggins.

*University of Cambridge.*

Speciation is often complex, leaving behind a messy history of genealogies across the genome. The discordant histories of different genomic regions reflect both incomplete lineage sorting and gene flow, which, in turn depend on geography, natural selection, effective population size, and genomic features such as inversions and recombination rate variation. Using whole-genome sequencing of sympatric and allopatric populations of three species of Heliconius butterflies, we show that the genealogical history of a locus depends strongly on where in the genome the locus lies and on the time scale of speciation. Specifically, between one pair of species, gene flow is greater near chromosomes ends and on small chromosome, where recombination rates are higher. Between another pair, the distribution of gene flow across the genome is more even. We propose that this difference reflects differences in the timing of hybridisation between these pairs of taxa. This work helps to disentangle the effects of various factors on the emergence of reproductive isolation between incipient species.

# FUNCTIONAL SPECIATION GENOMICS OF THE ANOPHELES GAMBIAE COMPLEX (51792)

**Frederic Tripet**, Fred Aboagye_Antwi, Nahla Alhafez, Abdoulaye Niang, Gareth Weedall, Doug Paton, Jessica Brothwood, Sharanjit Kandola, Abdoulaye Diabate.

*School of Life Sciences, Keele University, United Kingdom; Department of Animal Biology and Conservation Science, Faculty of Sciences University of Ghana Legon; Institut de Recherche en Sciences de la Santé/Centre Muratz, Bobo-Dioulasso, Burkina Faso; Centre for Genomic Research, University of Liverpool, Liverpool, UK.*

Anopheles gambiae exhibits complex populations and a number of cryptic taxa have been described. Genome-wide studies have shown that speciation in this species occurs through the divergence of a few loci characterized by reduced recombination and divergent selection. Such 'islands of speciation', located in pericentromeric regions of chromosomes X, 2L and 3L are thought to contain genes responsible for assortative mating in complex An. gambiae populations. We took two functional genomic approaches in order to identify which of these island(s) is crucial for assortative mating. In the first, laboratory recombinant strains differing only at their X-island were created by selective introgression. Recombinant strains that mated consistently assortatively were identified and their genome re-sequenced in order to broadly map assortative mating genes to the X-chromosome island of speciation. In the second approach we performed SNP genotyping of wild individuals captured from swarms from an
area with introgression between cryptic taxa. Genetic analyses of these natural recombinants
enabled us to confirm the strong association between the X-island and swarm spatial
segregation in field populations. Both approaches emphasize the importance of X-island loci
for the speciation process and constitute fundamental steps towards the identification of genes
of pre-mating reproductive isolation in this important species complex.

Ant hybrids reveal genomic features underlying speciation (51826)

Jonna Kulmuni, Kishor Dhaygude, Pekka Pamilo, Roger Butlin.

University of Sheffield; University of Helsinki.

Ants have rarely been used in speciation studies, yet they offer unique advantages. Their haplodiploidy, where males are haploid and females diploid, can aid in discovering genetic elements underlying speciation. We have discovered a hybrid ant population, which displays a rugged genomic landscape of differentiation with gene flow. Specifically, we find two groups of haploid males, representing parental gene pools, and females that are hybrids between these gene pools. This means introgression is permitted in diploid females but selected against in haploid males. Accordingly, we observe strong selection in haploid males: hybrid individuals are present at egg stage, but die during development. This provides a unique opportunity to study genome areas underlying reproductive isolation because, rather than relying on genome scans of differentiation, we can observe selection directly. To identify genomic regions that are responsible for hybrid male death and reduced gene flow between the parental gene pools, we are comparing the genomes of males and females. When analyzing the most variable regions of the genome, preliminary results identify SNPs in several contigs involved in hybrid male death and so reproductive isolation. Future analysis will reveal the identity, size and distribution of these genomic regions harboring barriers for gene flow.

The role of hybridization in the evolution of alpine Coenonympha butterflies
(52339)

Thibaut Capblancq, Laurence Després, Jesus Mavarez.

Laboratoire d'Ecologie Alpine (LECA), Grenoble, France.

Hybridization events have become central elements in animal evolution studies during the last decade and new methods in population genomics and model testing now allow for disentangling complex evolutionary histories. Interspecific crosses are recognized to be involved in key evolutionary processes such as local adaptation, colonization of new environments, speciation and extinction. We evaluated the role of hybridization in diversification and adaptation in complex of three Coenonympha butterfly taxa present in the Alps. Morphological, genetic and ecological analyses allowed us to prove the hybrid origin of
one of them: the Darwin's Heath (C.darwiniana). This lineage emerged after hybridization events between the Pearly (C.arcania) and the Alpine Heath (C.gardetta) approximately 10,000 years ago and with different parental contributions. It is now completely stable in two distinct restricted areas where its intermediate phenotype seems locally advantageous considering the fact that it completely excludes its parent species. Moreover, current contact zones show contrasting ongoing hybridization patterns, and although species seem to keep their integrity the reproductive isolation between them is far from complete. The analysis of introgression patterns, discussed in regards to climatic variables discriminating populations and species, promise new insights for understanding the role of hybridization in adaptation for this butterfly complex.

Nestedness and turnover in the genetic diversity of marine species across the
Indo-Pacific Ocean (52352)

**Libby Liggins**, Eric D. Crandall, J. David Aguirre, Michelle R. Gaither, Chris E. Bird, Rob J. Toonen, DIPnet members, Cynthia Riginos.

Massey University, Auckland; University of Hawaii; Durham University; Texas A&M
University - Corpus Christi; Diversity of the Indo-Pacific Network; The University of
Queensland.

The Indian and Pacific Oceans contain much of the world's marine biodiversity, but species and genetic lineages are not evenly distributed throughout this region. Understanding the generality of genetic breaks and genetic diversity gradients is important for describing the evolution of biodiversity and assembly of marine communities in this region; however the large population sizes and high dispersal of many marine species result in consistently high genetic diversity across species ranges (based on haplotype/nucleotide diversity) and obscure genetic breaks (based on distance measures and fixation indices). Here we complement traditional population genetic measures with measures originally conceived for comparing species compositions among communities. We applied nestedness and partitioned beta-diversity measures to mitochondrial genetic datasets for >100 marine species contributed by DIPnet (formed by the National Evolutionary Synthesis Center working group 'Advancing genetic diversity research in the Indian and Pacific Oceans'). We describe genetic diversity gradients considering nestedness and turnover to identify evolutionary 'sinks' (where immigration predominates) and 'sources' (where mutagenesis is evident), and reveal the significance of nestedness and turnover in forming genetic breaks. These measures, commonly used in community ecology, provide a nuanced understanding of genetic patterns in the Indo-Pacific that cannot be detected using traditional population genetic measures.

Specificity of the microbiome: insights from Daphnia hosts. (52516)

Samuel PICHON, Mahendra MARIADASSOU, Dieter EBERT.
Environmental and host genetic factors shape the composition of host-associated microbiota. To estimate the relative importance of each of both factors, we characterized the structure of the bacterial communities by amplicon pyrosequencing in three sympatric Daphnia species and of their environments (pond water and sediments). The three Daphnia species harbor a unique and diverse microbiota dominated by Proteobacteria, including members of the Comamonadaceae family. Previous results and the global similarity of these three symbiotic communities suggest that some of these associations may be evolutionary stable. However, differences among Daphnia species resemble the host phylogenetic relationships, suggesting that the hosts evolved with specific microbiota and that genetic factors are predominant in structuring their microbiota. We developed a local specificity index and introduce a permutation based test to assess the significance of the specificity. Analysis of multiple datasets (Daphnia, humans, etc.) suggests that microbial species that are specific to one habitat are most abundant in that habitat. The positive association between abundance and specificity was found in every dataset. We suggest that this relationship is a main structuring force of microbiota.

## From neutral theory to competition-dispersal trade-off: dispersal polymorphism effects on species diversity patterns (52634)

Fabien Laroche, **Philippe Jarne**, Thomas Perrot, François Massol.

*AgroParistech - CEFE; CNRS - CEFE; CNRS - GEPV.*

Neutral models provide important insights on patterns of species diversity in metacommunities. Introducing some variance in the carrying capacity of local communities may select for dispersal polymorphism under otherwise neutral conditions in metapopulation models. We extend this approach to a neutral metacommunity using a multi-species, multi-community model and show that dispersal polymorphism may readily emerge both within- and among-species depending on community carrying capacity distribution. Importantly small communities are occupied by dispersing species ("drifters") while large communities harbours species with limited dispersal ("dwellers"). When dispersal converges toward a unique evolutionarily stable equilibrium, diversity within communities and dissimilarity among communities do not differ qualitatively from neutral expectations. This is no more true when a dispersal polymorphism can emerge, suggesting that deviation from neutral predictions can be detected when comparing diversity indices among communities differing in carrying capacity. We discuss how our model contributes to unify two classical approaches in metacommunity ecology, namely neutral and competition-colonization models.

## Evolution of ecological communities through the lens of an island chronosequence (52653)
**Rosemary Gillespie**, Andrew Rominger, Jun Ying Lim, Fernanda Valdavinos, John Harte, Kari Goodman, Daniel Gruner, Kerry Shaw, Donald Price.

*University of California; Pacific Ecoinformatics; University of Maryland; Cornell; University of Hawaii Hilo.*

Islands are bedrock model systems in the development of ecological and evolutionary theory. The Hawaiian Islands in particular have expanded our understanding of island biogeography, with phylogeographic studies of rapid diversification and the dynamics of adaptive radiation overlaid upon a detailed understanding of ecosystem development and senescence. These studies demonstrate the overriding importance of in situ speciation in biodiversity patterns of highly isolated archipelagoes, beyond the reach of equilibrium colonization dynamics. We synthesize ecological and evolutionary perspectives to analyze processes driving emergent patterns of island biodiversity. We apply this approach to a simple and relatively isolated system that occurs across a 5 million-year space-for-time chronosequence provided by the island hotspot. We use this natural experiment to develop a novel analytical pipeline that combines both macroecological (interaction networks and maximum entropy inference) and evolutionary (population genetics and phylogenetics) approaches and hence build a predictive understanding of the interplay between ecology and evolution in dynamically shaping the macroecology of complex ecosystems.

Session 2 TUE GEN C 3

## Coevolution of the sex chromosomes in Drosophila melanogaster (52014)

**Katrine Lund-Hansen**, Edward H. Morrow, Jessica K. Abbott.

*University of Sussex; Lund University.*

Theory predicts that the Y chromosome may accumulate genes beneficial for males, even if these are harmful to females. As the Y chromosome is not present in females, selection does not act directly against these sexually antagonistic genes. Genes on the X chromosome would then be predicted to evolve to counteract the harmful Y genes or become resistant to them. To test this, we carried out a sex chromosome replacement experiment in males from five outbred, wild type, lab-adapted Drosophila melanogaster populations with different geographic origins. We replaced either the X or the Y chromosome and found that half of the novel genotypes had a significantly higher reproductive fitness than their source population. This change in fitness was not caused by interactions with the autosomes, but by the mismatching of the sex chromosomes, indicating that coevolution of the sex chromosomes must have occurred. We will present data on the effect of the introduction of a novel sex chromosome on various components of male fitness. We will also present a novel theory about the nature of sexually antagonistic coevolution on the X and Y.
# Evolution of an unusual sex determination system in a Mammal, the African pygmy mouse *Mus minutoides* (52017)

**Paul Saunders**, Ophélie Ronce, Pierre-André Crochet, Frédéric Veyrunes.

*Institut des Sciences de l'Evolution de Montpellier, CNRS, Université de Montpellier, France; Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, Montpellier, France.*

All therian mammals have a similar XX/XY sex determination system (SDS) except for a dozen species. In the African pygmy mouse <i>Mus minutoides</i>, males are XY, and there are three types of females: XX, XX* and X*Y (the asterisk designates a sex-reversal mutation on the X chromosome). The evolution of such a system is a paradox as sex-reversal mutations lead to sterility or subfertility in mammals, precluding departure from the standard system. Nevertheless, the X* is old (>0.9My) and highly prevalent in this species. To investigate the evolutionary forces involved in the emergence and maintenance of this system, an empirical approach and mathematical modelling are combined.

Data gathered from our laboratory colony reveal (i) that X*Y females have a greater reproductive success and (ii) the existence of sex chromosome transmission distorters. These findings can be related to two hypotheses proposed to explain transitions in SDS: Fitness differences between genotypes and sex-ratio selection. Our mathematical models suggest that either feature could be responsible for the appearance of the X* and that they both participate in its maintenance. These results provide valuable insight into understanding the constraints acting on SDS with highly heteromorphic sex chromosomes and conditions that can loosen these constraints.

Session 2 TUE GEN C 3

# The PhyloSex project: towards a better understanding of sex determination diversity and sex chromosome evolution in fish. (52201)

Jennifer Anderson, Christophe Klopp, Hugues Parrinello, Laurent Journot, John H. Postlethwait, Yann Guiguen, **Manfred Schartl**.

*INRA, Laboratoire de Physiologie et Génomique des Poissons, 35042 Rennes Cedex, France; INRA, SIGENAE, UR875, INRA Auzeville, BP 52627, 31326 Castanet-Tolosan Cedex, France; MGX (Montpellier Genomix), 34094 Montpellier Cedex 05, France; University of Oregon, Institute of Neuroscience, Eugene OR 97403, USA; University of Wuerzburg, Physiological Chemistry, Biocenter, 97074 Wuerzburg, Germany.*

Fish show a great variety of sex determination mechanisms, which in the case of genetic sex determination is linked to a similarly high variability of sex chromosome differentiation. Curiously, neither phenomenon follows any obvious phylogenetic pattern. To obtain a better understanding of the biological meaning of the diversity of sex determination and the mechanisms driving sex chromosome evolution we are attempting to decipher the molecular basis of the primary sex determination mechanisms and the structure and genetic organization of sex chromosomes across a broad diversity of rayfin fish. On the one hand we are analyzing a collection of species that represent major branches of the fish tree of life and on the other
hand we focus on closely related species within branches of the phylogenetic tree
(Esociformes, Danios, Poeciliids). We use high throughput marker mapping in 40 species as
well as transcriptomics and long insert clone sequencing to delineate sex-specific
chromosomal regions and to identify candidate sex determining genes. Our first results
indicate that many species harbor very poorly differentiated sex-chromosomes. Our RAD-tag
based approach led to the identification of sex-specific markers, allowing to delineate the
extent of recombination suppression. We also identified candidate sex determining genes in
some species.

Evolution of sex-determining modes in amniotes: transitions, stability and
ancestral state (52534)

Lukas Kratochvil, Michail Rovatsos, Marie Altmanova, Jasna Vukic, Martina Pokorna.

Charles University, Prague; Czech Academy of Sciences, Libechov.

It is believed that in contrast to mammals and birds frequent turnovers of sex chromosomes and transitions between genotypic sex determination (GSD) and environmental sex determination (ESD) in both directions are typical for poikilothermic amniotes. Nonetheless, using comparison of genes linked to X and Z sex chromosomes across wide species sampling, we demonstrate that sex chromosomes are highly conserved for dozens million of years in iguanas and snakes. Current knowledge on the homology of sex chromosomes among particular GSD clades as well as on the phylogenetic distribution of GSD and ESD is in agreement with ancestral ESD for amniotes. Transitions from ESD to GSD were frequent, but transitions in the opposite direction were rare (if any). Previously, we argued that this stability of GSD with respect to ESD could be attributed to the stability of well-differentiated sex chromosomes. However, within reptiles, we have recently found two independent disappearances of highly differentiated sex chromosomes. Still, even here the derived states represent again GSD, not ESD. We call for a general explanation of the resistance of GSD to the invasion by ESD and suggest that it may be based on the wider potential to resolve sexual conflict under GSD.

The evolution of sexual specialization in an artificial dioecious fungus (52652)

Bart Nieuwenhuis, Hanna Johannesson, Simone Immler.

*Department of Evolutionary Biology, Uppsala University; Department of Systematic Biology, Uppsala University.*

One possible scenario for the evolution of males and females is the occurrence of mutations in
a simultaneous hermaphroditic ancestor acting as sex determining loci, which render
individuals male or female. This division into male and female individuals not only should
lead to phenotypic divergence but also to rearrangements in the underlying genomic
architecture. To study this important first steps in the evolution of two separate sexes from a
hermaphroditic ancestor, we created mating-type specific male-sterile and female-sterile
strains of the haploid fungus Neurospora crassa. Effectively this creates dioecious individuals,
in which the mating type locus has become a sex-determining locus. Using experimental
evolution with these dioecious strains, we studied how the strains adapt to their novel role as
male or female, both at the phenotypic and the genetic level. Sexually antagonistic traits are
expected to become associated with the sex determining locus, either due to mating type
regulated expression or through linkage. We will present measurements on male and female
fitness contributions from competition essays between dioecious and hermaphroditic
individuals. Then we will describe phenotypic and genetic changes in the male and female
strains after 15 generations of experimental evolution.

Non-genetic transmission and sex-linked inheritance of prenatal maternal effects in a precocial bird (51834)

**Barbara Tschirren**, Ann-Kathrin Ziegler, Monika Okuliarova, Michal Zeman, Joel Pick, Mathieu Giraudeau.

University of Zurich; Comenius University Bratislava.

Resources and developmental cues provided by the mother during the first stages of life can
have pronounced and long-lasting consequences for offspring morphology, physiology and
behavior. Whereas the role of such prenatal maternal effects in mediating offspring
phenotypic plasticity is well documented, their potential consequences for subsequent
generations are still debated. Important mediators of prenatal maternal effects in birds are
hormones that are transmitted from the mother to the eggs. Using a breeding experiment over
three generations in Japanese quail (Coturnix japonica), we show that maternal yolk hormone
deposition is inherited exclusively along the maternal line, suggesting W-chromosome
linkage. Furthermore, we demonstrate that an experimental manipulation of yolk hormones in
the eggs, mimicking environmentally-induced maternal effects, affects the daughters' egg
composition later in life, thereby influencing the grand-offspring's developmental trajectories.
We assess the adaptive value of such a non-genetic transmission of information across
generations and the role of sex-specific selection in shaping the evolution of sex-linked
inheritance of maternal effects.

Does molecular pleiotropy constrain evolution, plasticity or both? A proteomic perspective in a salmonid fish metapopulation (51853)

Spiros Papakostas, Asbjørn Vøllestad, Matthieu Bruneaux, Tutku Aykanat, Joost Vanoverbeke, Mei Ning, **Craig Primmer**, Erica Leder.
The significance of gene expression pattern modification as a mechanism promoting rapid evolution has received considerable attention recently but the relative roles of plastic vs evolutionary expression change remain unclear. We conducted a common garden experiment and studied the proteomic expression profiles of European grayling (Thymallus thymallus) sub-populations that have adapted to different thermal environments in just 25 generations. The proteome expression changes included both evolutionary and plastic components, with each component having an independent, but complementary, effect on the expression profile. A QST-FST analysis indicated that the observed differences in proteomic expression profile between cold and warm origin sub-populations likely included an adaptive component. We also found that temperature-driven gene expression changes were constrained by the level of gene pleiotropy estimated by either the number of protein interactions or gene biological processes. Genes with low pleiotropy levels were the main drivers of the observed changes in both plastic and evolutionary global expression profiles, while highly pleiotropic genes had a limited expression response to temperature treatment. These findings provide important insights into the molecular mechanisms facilitating rapid adaptation in changing environments and suggest that gene pleiotropy should be considered more carefully when interpreting gene expression profiling data

# Evolutionary and ecological plasticity in short order: genome-wide evidence for in-situ evolution and adaptation in invasive Florida Burmese pythons (52049)

Todd Castoe, Daren Card, Drew Schield, Margaret Hunter, Kristen Hart.

Substantial evolutionary changes are thought to happen over long time periods in most species, making analyses of natural selection and its effects on the genome difficult. Invasive species, however, represent a promising model for analyzing the processes of evolution and adaptation on timescales that are tractable for study, and have been shown to demonstrate rapid evolutionary responses and high plasticity over short or 'ecological' timescales. The invasive Burmese python (Python molurus bivittatus) is ideal for studying rapid evolution due to its recent establishment and proliferation in sub-tropical Florida, a location with climatic conditions that are notably different from those in the species' native range of tropical Southeast Asia. Among other major selective events that have impacted this introduced population, a significant die-off (>50%) of individuals in the Florida python population (FPP) occurred during a 2010 freeze event. We used genome-wide SNP sampling of the FPP (via RADseq) before (2007) and after (2013) the freeze event to test for evidence of evolution and locus-specific selection. We found multiple regions of the genome that appear to show major shifts in heterozygosity over a surprisingly short time period (time of a single generation), indicating in situ evolution and adaptation in the FPP.
# Bridging Ecology and Evolution by Symbiotic and Epigenetic Mechanisms
(52052)

**Yoav Soen.**

*Weizmann Institute of Science.*

While adaptations to novel environments extend over evolutionary timescales, a new environment can emerge already within a single generation and can immediately impact the physiological and epigenetic state of the organism. Whether and how the initial response might be connected to longer-term establishment of new adaptations are not clear.

We take an experimental approach to address these questions by studying responses of flies to novel scenarios of stress. We identified epigenetic- and symbiotic-mediated mechanisms which promote increased developmental plasticity under stress, influence the germline, and contribute to non-Mendelian transfer of variation across generations.

I will discuss these epigenetic- and symbiotic-mediated processes and their potential contribution to the establishment of initial adaptations that can bridge part of the gap between ecological and evolutionary processes.

# Plastic vs genetic responses to temperature acclimation: quantitative traits to transcripts. (52063)

Allannah Clemson, **Marina Telonis-Scott**, Carla Sgro.

*Monash University.*

Relating environmental variables to a range of phenotypes expressed by a genotype is a ‘tried and true’ method for studying responses to varying environments. Given the critical role of temperature in shaping the geographic distributions in terrestrial organisms, attention is now shifting to consider thermal performance when assessing the potential impacts of climate change. Examining populations that inhabit diverse thermal environments provides insights into traits and genes that are important in environmental adaptation, and can enhance predictions of species’ ability to mitigate any deleterious effects of a changing environment. Here we use the fruit fly Drosophila melanogaster as a model to understand how environmental adaptation affects thermally responsive traits and genes. We collected two outbred populations along the Australian eastern coast (north and south) and developed them at six temperatures. We then compared the expression of temperature responsive candidate genes as well as life-history traits to understand the link between genotype and phenotype driving thermal adaptation. Our goal is to develop an approach to link climatic preference with stress performance, life-history, morphology and molecular processes. Ultimately, can genes that respond differentially to developmental temperature explain fitness differences
across environmental gradients, and thus provide insight into future responses to climate
change.

Adult transcriptome variation is determined by egg to adult development time
in a desert drosophilid (52041)

William J. Etges, Cassia de Oliveira, Subhash Rajpurohit, Allen Gibbs.

University of Arkansas; Lyon College; University of Pennsylvania; University of Nevada, Las Vegas.

Complex life cycles offer an opportunity to investigate the genetic influences of early life stage variation on later components of the life history. We investigated whole genome transcriptional variation in populations of Drosophila mojavensis by day of preadult development time (DEVT) in aged adults reared on different host plants. Because DEVT variation is genetically correlated with sexual isolation between populations as well as cuticular hydrocarbon differences, transcriptional variation in adults differing in DEVT is of direct consequence to understanding host plant related adaptation, life history evolution, and reproductive isolation. We found hundreds of genes enriched for different functions in adults that varied due to DEVT including those influencing gene regulation, mitochondrial energetics, and cuticular hydrocarbon production.

Within and across generation life-history responses to nutritional stress during
development (51875)

Marjo Saastamoinen.

University of Helsinki.

Organisms in the wild are constantly faced with a wide range of environmental variability, such as fluctuation in food availability. Understanding the processes and underlying mechanisms that allow organisms to cope with such environmental variation is a key challenge in evolutionary ecology. I will synthesise across studies in which we have assessed the influence of short-term nutritional stress during development on adult life-history variation in the Glanville fritillary butterfly (Melitaea cinxia). Poor developmental conditions often have a negative impact on fitness-related traits, such as reproduction and lifespan. However, conditions experienced during development can sometimes be used as cues for the likely environmental condition the individual will encounter later on in life (i.e. predictive adaptive responses). Accordingly, individuals can shape their adult physiology or life history in a way that allows them either to deal with the predicted conditions later on in life or to move away from these deteriorating environments. Predictive adaptive responses seem to occur also across generations, as mothers that experienced nutritional stress during their own
development produce offspring that have improved compensatory strategies to cope with
nutritional stress. We are currently assessing whether differences in methylation underlie
these observed phenotypic differences in response to developmental nutritional stress.

Antagonistic coevolution with competing consumers alters the dynamics of selection over time (52528)

Frickel Jens, Becks Lutz.

Community Dynamics Group, Dept. Evolutionary Ecology, Max Planck Institute for
Evolutionary Biology.

Coevolutionary changes in antagonistic interacting populations can constantly change the mode, strength and direction of selection through a link between ecological and evolutionary dynamics on the same time scale. To explore the role of eco-evolutionary dynamics and their effects on variation in selection over time, we conducted a series of experimental evolution studies using host-virus systems. We will present results from experiments where we compared the evolutionary and ecological dynamics of experiments when host and virus coevolved with and without an additional consumer for the host (predator). We found that predator and virus could only coexist after the host evolved a general resistance against the virus and that coexistence of the two consumers shifted the ecological dynamics towards cyclic populations compared to the experiments with only host and virus. Most importantly, the presence of the predator changed the evolutionary dynamics from fluctuating selection when host and virus evolve alone, to constant selection when virus, host and predator coexisted. Overall, our study shows the important consequences of rapid evolutionary change and highlights that the details of coevolutionary dynamics matter for community stability (cycles vs. stability) and structure (coexistence), which in return determines type of selection (fluctuating vs. constant).

Stress response of mutation accumulation lines of the green algae
Chlamydomonas reinhardtii across two environmental gradients (52130)

Susanne Kraemer, Andrew Morgen, Peter Keightley, Nick Colegrave.

University of Edinburgh.

Understanding the distribution of fitness effects (DFE) of novel mutations is central to many areas of evolutionary biology. Importantly though, mutational effects are not fixed but will depend on the environment that the organism experiences. However, the effect of the environment on DFE, expressed as changes to the mean and variance of fitness, has been rarely investigated experimentally. Intuitively it might be expected that selection coefficients against deleterious mutations will increase in stressful environments but experimental tests so
far have produced conflicting results. Clones of the green algae Chlamydomonas reinhardtii were previously subjected to a mutation accumulation experiment. Here, we measured fitness of two independent MA lines and their ancestors across two different environmental gradients, increasing salt and decreasing phosphorous. We investigated changes in expressed genotypic variation and the consistency of the genetic response to environments between the two MA lines, between the two different stressors, between MA lines and their ancestors and in relation to the severity of stress. This allowed us to determine how DFE changes in response to stressful conditions, which, in turn, will determine the future capacity for adaptation in this model plant.

# Geographical variation in predation pressure toward warning signals of an Arctiid moth Parasemia plantaginis (52702)

Katja Rönkä, Bibiana Rojas, Emily Burdfield-Steel, Swanne Gordon, Ossi Nokelainen, Tönis Tasane, Janne Valkonen, Johanna Mappes.

*University of Jyväskylä; University of Tartu.*

The wood tiger moth (P. plantaginis) is an aposematic species of which hind wing coloration can be white, yellow, orange or red combined with variable amount of black pigmentation. Throughout its Holarctic distribution both monomorphic and polymorphic populations exist. We asked whether differences in frequency dependent selection by predators could explain geographic differences in warning signals. We recorded local passerine and Lepidoptera communities during large-scale field experiments in four geographic locations (in Estonia, Scotland, Georgia and Southern Finland) where artificial moths of white, yellow and red hind wing coloration were exposed to natural predators. In Estonia white morphs, in Scotland yellow morphs and in Caucasus red morphs dominate whereas in Finland white and yellow morphs coexist. Predation pressure differed between the populations and natural selection seemed to favor locally common morphs in Scotland (yellow) and in Georgia (red) as expected according to the theory of aposematism. However, in Finland and Estonia we did not find evidence of positive frequency dependent selection. In addition to the local wood tiger moth population, we found some evidence that the structure of predator populations as well as local alternative prey communities influence the strength and direction of selection contributing to warning signals.

# Environmental suitability influences the evolvability of morphological traits: linking biogeography and evolutionary dynamics (52708)

Jesus Martinez-Padilla, Alba Estrada, Regan Early, Francisco Garcia-Gonzalez.
Estación Biológica de Doñana; CIBIO/InBIO, Universidade de Evora; College of Life and Environmental Sciences, University of Exeter; Centre for Evolutionary Biology, The University of Western Australia.

Natural selection is the main mechanism driving evolution. Yet, our knowledge on how evolution works under different environmental circumstances is extremely limited in wild populations. Here we explore how environmental variation influences the evolvability of phenotypic traits of European wild bird populations. We reviewed studies that provided, or allowed calculation of, the coefficient of additive genetic variation (CVA) as a proxy of the ability of populations to respond to natural selection. We obtained 132 estimates of CVA of morphological traits from 13 species of 19 populations. We built Species Distribution Models of those species in Europe at a resolution of 50x50Km2 considering spatial, topographical and climatic variables with the favourability function. We then matched the environmental suitability of the location with the CVA of each population and species we had data from. We explored the association between favourability and CVA. We found that CVA of morphological traits was higher at intermediate environmental suitability and lowest in very favourable or unfavourable environments. Our results highlight the need to consider the populations' environmental context to accurately contextualize evolutionary potential.

Session 2 TUE POL A 28

## Climate-change driven evolution of an ornament in a wild bird (52921)

Simon Evans, Lars Gustafsson.

Department of Animal Ecology, Uppsala University.

Despite extensive empirical research, and theoretical expectations of rapid adaptation in response to selection, empirical evidence for contemporary evolution of secondary sexual traits is scarce. We explored this issue in a population of collared flycatchers (Ficedula albicollis), in which the heritable (~35%) ornamental forehead patch of males has shown a marked phenotypic decline in size over 34 years. Based on estimates of annual fitness selection, we report a reversal in selection on forehead patch size over the study period, driven by climate-dependent viability selection (interannual survival) on males: early in the study, males with larger ornaments had higher survival. Conversely, in latter years, when temperatures at the breeding ground have been higher, less ornamented males had higher survival. Using a Bayesian animal model to quantify genetic and environmental variation in forehead patch size, we find a highly significant temporal decline in the breeding value of males, and show via simulations that genetic drift is unlikely to account for this. Our study thus demonstrates evolutionary reduction of ornamentation in the wild within the timeframe of a contemporary study and in response to climate change.

Session 2 TUE POL B 20

## Genomics of local adaptation in the Mediterrenean blue tit Cyanistes caeruleus (52007)
Demonstrating local adaptation in nature requires establishing connections not only between genotype, phenotype and fitness, but also between genomic differentiation and its covariation with habitat heterogeneity. Here, we investigated the origins of a strong habitat-linked phenotypic differentiation across Mediterranean populations of wild blue tits (Cyanistes caeruleus) breeding in a highly heterogeneous environment. First, we tested for population genomic structuring related to habitat type. By applying a RAD-Seq approach to generate c. 12 000 SNPs, we detected large-scale and fine-scale genetic differentiation between populations. This included differentiation in adjacent habitats within Corsica less than 6 km apart, which was unexpected in highly mobile organisms such as birds. Complementary population genomic analyses revealed a pattern of isolation-by-environment (IBE) where genetic differentiation correlated with habitat type independently of geographic difference. Second, we established a quantitative genomic framework to study local adaptation in the Mediterranean blue tit. We compare pedigree and marker-based heritability for key reproductive traits, which are also known to differ between habitats. Third, we discuss the importance of using sample replicates and complementary statistical inference for genomic data validation to generate reliable insight into the genomics of local adaptation.

# Utilizing large sampling frames to investigate the genomic determinants of short-term adaptation in Mycobacterium tuberculosis (52282)

**Jessica Hedge**, Timothy Walker, Sarah Walker, Derrick Crook, Tim Peto, Daniel Wilson.

Short-term adaptation plays a major role in the success of Mycobacterium tuberculosis, the aetiological agent of TB disease in humans. The most obvious example is the emergence of drug resistance under the strong selective pressure from antimicrobial drugs. We have also identified signatures of short-term selection outside of genes associated with any known resistance, suggesting that M. tuberculosis must also adapt to different local environments within hosts. Although the exceptionally low clock rate of this species makes studies of within host adaptation challenging, intensive population-level sampling frames can increase the sensitivity to detect variants occurring over the short term. By performing phylogenetic analyses of 3651 M. tuberculosis whole genome sequences representing the global diversity of this pathogen, we have investigated the genetic pathways involved in local adaptation to the host environment over the short-term. The genetic variants identified in this way may help to explain why M. tuberculosis occasionally leaves the lungs, from where it can successfully transmit to other hosts and easily enter the bloodstream, to infect other tissues, which represent an evolutionary dead-end. By testing for associations between sites under selection and disease manifestation, we can begin to characterise the genomic signatures of adaptation in this pathogen.
# Signatures of selection in an admixed feral chicken population (52293)

**Martin Johnsson**, Eben Gering, Pamela Willis, Thomas Getty, Dominic Wright.

*IFM Biology, Linköping University, Linköping, Sweden.; Zoology Department, Michigan State University, East Lansing, Michigan, U.S.A.; Biology Department, University of Victoria, Victoria, Canada.*

Feralisation is the evolutionary process that occurs when a population of domestic animals is returned to wild conditions. Domestication as well as feralisation can serve as models of adaptation to new environments. Our observations of phenotypes and genetic data suggest that feral chickens of Kauai are an admixed population of wild and domestic chickens. We performed whole-genome SOLiD sequencing on 23 Kauai chickens (~5X individual coverage), called single nucleotide variants and performed selective sweep mapping by sliding window pooled heterozygosity. As a comparison, we reanalyzed a dataset of selective sweeps in domestic chickens. Consistent with their probable admixed origin, the Kauai population had on average higher heterozygosities than domestic chickens. We found 37 putative selective sweeps on Kauai, largely separate from those in domestic chickens, and potentially driven by feralisation and adaptation. One among the potential sweeps on chromosome 13 is close to a candidate gene for relative comb mass identified in a laboratory cross between wild and domestic chickens. We speculate that this is due to restoration of natural and sexual selection on comb size on previously domesticated genotypes. High heterozygosities suggest ongoing feralisation on Kauai that may offer an opportunity to map this process in real time.

# Experimental genomic tests for pollution driven rapid evolution in the Mediterranean mussel (52305)

**Anamaria Štambuk**, Stuart Dennis, Dorotea Polović, Maja Šrut, Víctor Soria-Carrasco, Zachariah Gompert, Vid Baković, Goran Klobučar, Patrik Nosil.

*Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000 Zagreb, Cr; Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK; Department of Biology, Utah State University, Logan, UT 84322, USA.*

Anthropogenic disturbance can rapidly and substantially alter the environment such that exposed organisms are challenged to quickly adapt to these changes. We studied evolutionary responses to pollution in marine environments using the Mediterranean mussel Mytilus galloprovincialis. We sampled 15 natural populations along a pollution gradient and used a subset of these to perform transplant experiments between clean and polluted environments in both the wild and in lab mesocosms. The results of the experiments showed consistent differential survival between treatments and source populations driven by an acclimatization effect in the wild transplant and by population by environment interactions in the mesocosm experiment. For over 1800 mussels used in these studies we collected genome wide SNP data
using a genotype-by-sequencing approach. These SNPs were analysed to test for genetic
structure in natural populations and the genomic architecture of survival (i.e., fitness) in the
experiments. By combining data obtained from the native populations and two types of
transplant experiments we identified interactions between environment, genotype, and fitness,
thus providing new insight into pollution driven evolution and the effect of adaptive processes
on the mussel genome.

Parallel and non-parallel genomic signatures of selection in three-spine
sticklebacks from different regions (52380)

Shenglin Liu, Anne-Laure Ferchaud, Michael M. Hansen.

Aarhus University; Université Laval.

Multiple independent colonizations of freshwater areas by marine three-spine stickleback represent some of the most well-known examples of parallel evolution, both at the phenotypic (especially lateral plate polymorphism) and genomic levels. However, whereas high degrees of parallelism are observed in some geographical regions (e.g. American northern Pacific), parallelism appears less pronounced in other regions (e.g. the North Sea and Baltic Sea in Europe). We test the hypothesis that the degree of similarity of environments and ecosystems between freshwater bodies also explains the degree of parallelism. Using RAD sequencing we analyze marine and freshwater sticklebacks from 1) Greenland, where ecosystems are very simple and similar across lakes, with only few fish predators present and 2) Denmark, where ecosystems are complex and differ strongly between habitats. In accordance with our hypothesis, we do find pronounced phenotypic and genomic parallel evolution in Greenland, but only limited parallel evolution in Denmark. We furthermore estimate divergence time between marine and freshwater sticklebacks and demographic history of populations in the two regions in order to rule out that different time since founding or strong bottlenecks could explain the differences of results.

Extreme local adaptation in Drosophila chemosensory perception (52494)

**J. Roman Arguello**, Margarida Cardoso-Moreira, Jaaved Mohammed, Jennifer K. Grenier, Srikanth Gottipati, Andrew G. Clark, Richard Benton.

*University of Lausanne, Center for Integrative Genomics; Cornell University, Department of Molecular Biology and Genetics; Cornell University, Department of Biological Statistics and Computational Biology; Translational Medicine and Think Team, Otsuka Pharmaceutical Development and Commercialization, Inc.*

How organisms adapt to new environments is of fundamental biological interest but is poorly
understood at the level of genes and neurons. A particularly interesting question regarding
local adaptation is how sensory systems and perception are altered during this process. To
investigate the extent to which selection has shaped the chemosensory perception within D.
melanogaster - a preeminent model for studying sensory neurobiology – we have analyzed
genome-wide polymorphism and divergence data from the Global Diversity Lines (84 D.
melanogaster genomes derived from 5 geographically diverse populations). By couching
population genomic analyses of chemosensory protein families within parallel analyses of all
other large protein families we demonstrate that, surprisingly, chemosensory proteins do not
stand out as outliers with respect to signals of adaptive differences between species. However,
chemosensory proteins do experience local adaption at extremely high rates, often displaying
the strongest signals of selection among large protein families. We show that adaptation has
operated almost exclusively on standing variation, and that positively selected genes often
harbor unanticipated levels of diversity. Our curated set of selected chemosensory proteins is
currently guiding functional studies aimed at understanding the phenotypic impacts of the
variants under selection.

Toll-like receptors in birds: diversifying selection, pseudogenization and gene duplication (51989)

Hana Bainova, Maria Weronika Gutowska, David W. Burt, Michal Vinkler.

Department of Zoology, Faculty of Science, Charles University in Prague, Czech Republic;
Department of Genomics and Genetics, The Roslin Institute and R(D)SVS, University of
Edinburgh, UK.

Toll-like receptors (TLRs) form an essential class of pattern recognition receptors that plays a
key role in the first line of vertebrate innate immune defence against various pathogens. Avian
TLR family comprises in its original state ten receptors, where each receptor homodimer or
heterodimer is capable of recognizing a distinct set of microbe-associated molecular patterns.
Herein we present the result of our investigation of avian TLR evolution. We analysed all
TLR sequences available from 65 bird species covering major avian clades. The sequence
data were extracted from whole genome sequences obtained within the Avian Genomes
project as well as from public sequence repositories. Our selection analyses revealed that
positive diversifying selection acts more on extracellular than on endosomal TLRs.
Furthermore, we described the unique phenomenon of TLR5 pseudogenization recently
published in passerines also in other bird taxa (e.g. in Psittaciformes, Cariamiformes,
Trogoniformes, Phaethontiformes, Eurpygiformes and Apodiformes). TLR7 duplication
predicted until today only in passerines seems to be common also in other avian taxa as e.g. in
Charadriiformes, Cuculiformes and Mesiornithiformes. The assessment of evolutionary
patterns explaining the genetic variability in genes of the TLR family may shed light on
selective pressures shaping host-parasites interactions on large evolutionary scales.
# Diversity through alternative splicing: Do Dscam1 splice variants respond to bacteria exposure? (52023)

**Sophie Armitage**, Wei Sun, Xintian You, Joachim Kurtz, Dietmar Schmucker, Wei Chen.

*University of Münster; Max-Delbrück Center for Molecular Medicine Berlin; VIB University Leuven.*

One way that a host can evolve diversity in immune recognition and effector molecules is through alternative splicing. It has been proposed that the extensively alternatively spliced gene Dscam1 (Down syndrome cell adhesion molecule), might be involved in pancrustacean immune responses against diverse parasites. It has been proposed that the phenotypically variable isoforms (combinations of exons) that it can produce may be involved in the recognition of diverse parasite epitopes, although evidence to support this is sparse. One prediction is that the Dscam1 gene expression of alternatively spliced exons is influenced by exposure to an immune elicitor. To test this hypothesis, for the first time in an immune context, we used Pacific Biosciences long read RNA sequencing methods to investigate splicing patterns after exposing Drosophila melanogaster and a cell line to live Escherichia coli. Using long reads allowed us to examine the expression of different isoforms. Contrary to our prediction, we found no significant changes in exon or isoform expression in response to bacterial exposure. However, these data represent only one of a vast number of possible host-microbe interactions. In order to test the general significance, future studies are needed to test other host-parasite combinations and more ecologically relevant conditions.

# Major-effect mutations provide resistance to viruses in natural Drosophila populations (52031)

**Chuan Cao**, Rodrigo Cogni, Michael Magwire, Frank Jiggins.

*University of Cambridge; University of São Paulo; Syngenta.*

Coevolutionary arms races between hosts and parasites mean that there is continual selection for novel ways to resist infection. We have used the powerful tools of Drosophila genetics and genomics to understand the evolution of resistance. By combining high-resolution QTL mapping and association studies we have found that there are a small number of major-effect polymorphisms that control virus resistance in natural Drosophila populations. For three of the genes involved, we have modified them to experimentally confirm the exact mutations involved, showing that diverse molecular changes can lead to resistance. A single amino acid change in the restriction factor pastrel dramatically increases the resistance against Drosophila C Virus. A transposable element insertion in gene CHKov1 results in a new transcript, which protects flies against sigma virus infection. Meanwhile, a large deletion in the protein Gcl1 makes flies resistant to sigma virus infection, likely by altering its role in RNA degradation. In all cases the resistant allele is the derived state and the genes often show signs of strong selection. Together our results indicate that major-effect mutations that provide resistance to viruses continually arise and are driven through populations by natural selection.
# Bumblebee immune response upon faecal transplant and microbiota community structure in host-parasite interactions (52154)

**Kathrin Näpflin**, Paul Schmid-Hempel.

*ETH Zürich.*

Microbial symbionts are suspected to closely interact with the host immune system. Recently, their role in mediating levels of resistance in host-parasite interactions has thus come into focus. So far, however, experimental investigations of the impact of the microbiota on the host immune system and vice versa are virtually absent. Experiments done in the bumblebee, Bombus terrestris, demonstrated that the microbiota both provides a protective function against the trypanosome gut parasite, Crithidia bombi, and mediates the specificity of the host-parasite interaction. Here, we investigated how the crosswise transplantation of "resistant" and "susceptible" faecal microbiota into "resistant" and "susceptible" backgrounds of microbe-free worker bees affects the activity of the host immune system. In a first step, we measured the primary immune gene expression response to the transplant. In a second step, we investigated if these gene expression patterns are associated with differences in the microbiota community structure as described by 16s rRNA sequence data. Our results underline the importance of the host genotype (i.e. resistance background) in host-parasite interactions. Most likely, the host genotype is able to exert selection via differences in gene expression upon the establishing gut community.

# Evolution of anti-parasitic behaviors in monarch butterflies (52207)

**Jaap de Roode.**

*Emory University.*

Hosts have evolved a wide variety of defenses against parasites, including anti-parasitic behaviors. Monarch butterflies (Danaus plexippus) are commonly infected with the protozoan parasite Ophryocystis elektroscirrha, which strongly reduces monarch survival, mating ability and fecundity. Monarchs are specialized on milkweeds as their larval food plants, and milkweed species with high concentrations of cardenolides (secondary toxic chemicals) reduce parasite infection and virulence. We investigated whether monarchs can use medicinal milkweeds to prevent or cure disease, and whether monarch medication behaviors depend on parasite risk in natural populations. Our experiments suggest that infected female butterflies preferentially lay their eggs on medicinal milkweeds that make their offspring less sick. Moreover, the type of medication behavior depends on parasite risk in natural populations. In eastern and western North America, where parasite risk is low, only infected monarchs had a preference for medicinal plants, indicating therapeutic medication. In contrast, in South Florida, where parasite risk is high, both infected and uninfected monarchs preferred to lay
eggs on medicinal milkweed, indicating prophylactic medication. Overall, our results suggest that monarchs can use medicinal milkweeds to mitigate the negative effects of their prevalent protozoan parasites, and that variation in parasitism risk contributes to variation in medication behavior.

# The effectiveness and costs of pathogen resistance strategies in a long-lived host (52294)

**Hanna Susi, Anna-Liisa Laine.**

*University of Helsinki.*

Hosts have evolved different strategies to resist pathogens but little is known about how variable, effective, and costly these mechanisms are in long-lived hosts. In the interaction between Plantago lanceolata and its powdery mildew causing fungus Podospahera plantaginis the same host may block infection by some strains of the pathogen while being susceptible to others and once infected, hosts may quantitatively mitigate disease development. We conducted a laboratory experiment to assess variation in resistance strategies across 41 plant genotypes originating from 8 P. lanceolata populations. To test stability and costs of different resistance strategies, we established multi-year experimental populations of plants possessing qualitative resistance, quantitative resistance, or susceptibility to disease. We found variation among the resistance phenotypes in laboratory with no evidence for trade-offs between qualitative and quantitative resistance strategies. Throughout the three year study qualitative resistance efficiently blocked infections but quantitative resistance was not effective against infection in the experimental populations. We detected fitness costs of resistance in the absence of the pathogen for qualitative and quantitative resistance compared to susceptible plants. Our results demonstrate that different resistance strategies can be maintained in a natural population by costs of resistance and by shifts in resource allocation under infection.

# Trade-off between dual roles of the gut in nutrient acquisition and immune defense: experimental evolution and physiological basis (52313)

**Tadeusz Kawecki, Roshan Vijendravarma.**

*University of Lausanne.*

In addition to its role in digestion and absorption of nutrients, the digestive tract is the first line of defense against enteric pathogens, and thus the site of potential evolutionary trade-offs between nutrient acquisition and immunity. We will present evidence for such a trade-off from experimental evolution, with Drosophila as the study system. We found that populations adapted during 160 generations of experimental evolution to chronic larval malnutrition became more efficient at extracting the diluted nutrients, but also more susceptible to
intestinal infection with the bacterial pathogen Pseudomonas entomophila. Detailed experiments reveal an unexpected mechanism of this trade-off: elevated predisposition to loss of intestinal integrity upon infection, leading to sepsis. These results provide a potential evolutionary explanation for the maintenance of genetic susceptibility to opportunistic intestinal pathogens.

# The adaptive value of within-individual covariation between floral signals and rewards. (51709)

**Santiago Benitez-Vieyra.**

*Instituto Multidisciplinario de Biología Vegetal (Universidad Nacional de Córdoba - CONICET).*

When pollinators visit a sequence of flowers they experience a continuum of variation in advertisement traits and in the amount and quality of reward, ranging from full rewarding to deceptive flowers. They can combine this information, evaluate the reliability of plant signals and use previous knowledge to decide when to leave that plant. Hence, in most plant species the within-individual covariation among signals and rewards could be the target of pollinator-mediated selection if pollinators verify the reliability of floral signals and penalize cheating individuals. We examined whether within-individual signal-reward correlations evolve under selection at micro- and macroevolutionary levels, detecting the occurrence of current phenotypic selection on natural populations and testing the adaptive divergence of floral signals in plants visited by different pollinators. In the latter case, we used a sample of Neotropical Salvia species and took advantage of the differential use of floral signals by bees and hummingbirds to predict which specific traits are predominantly associated with nectar reward at the within-individual level. Our findings support the idea that signal honesty is selected by pollinators and highlight the adaptive value of within-individual variation.

# Learning about natural variation of floral odors sets boundaries for generalization among flowers with the same reward value (51798)

**Brian H Smith, Fernando F Locatelli, Patricia C Fernandez.**

*Arizona State University; Universidad de Buenos Aires; INTA EEA Delta del Paraná y FAUBA.*

Floral odors are typically mixtures. Mixtures that have the same meaning – e.g. food - can vary in composition from flower to the next. Therefore a central problem in recognition of floral odors is generalization among flowers that differ but have the same meaning. We propose that mechanisms of plasticity in early sensory processing in the brain are central to solving this problem. Accordingly, plasticity should work to improve grouping of odors that
have the same meaning. Using synthetic mixtures that mimic natural odor variation, we studied how honey bees learn about and generalize among floral odors. We conditioned honey bees on a discrimination problem using synthetic mixtures that mimic natural variation among snapdragon flowers. We then employed bioimaging of calcium responses in projection neurons of the antennal lobe, which is the first synaptic relay of olfactory sensory information in the brain, to study how ensembles change as a result of conditioning. We show how neural networks in the antennal lobes become ‘tuned’ through plasticity to improve grouping of odors that have the same meaning. We argue that this tuning allows more efficient use of the immense coding space of the antennal lobe to solve the generalization problem with floral odors.

# Paternity analysis reveals mating patterns in an Antirrhinum hybrid zone incorporating sibships and phenotypes (51642)

Thomas Ellis, David Field, Nick Barton.

IST Austria.

Pedigree estimation of natural populations allows a direct and powerful insight into mating patterns of wild organisms and the traits which contribute to variation in reproductive success. I will present data on paternity for open-pollination seedlings from an Antirrhinum hybrid zone. Here yellow and magenta subspecies hybridise and form transgressive white, orange and pink pigmentation phenotypes. Comprehensive phenotypic sampling permits joint estimation of paternity and the strength of selection on floral characters. This is performed in a new Bayesian framework which combines information on phenotypes and shared alleles among siblings to assign relationships, which is efficient for modern SNP genotype datasets.

# The double role of Salvia viridis' extrafloral display (51644)

Yoram Gerchman, Tamar Keasar.

University of Haifa at Oranm.

Salvia viridis is a Mediterranean annual plant, growing in small groups ("patches"), and characterized by an extra-floral structure, a group of conspicuous purple tufts of leaves ("flags"), which terminate each vertical inflorescence. We have studied the role of these flags in the interaction of the S. viridis plant with different animals, both pollinators and herbivores, and found that removal of the flags increased herbivory. Furthermore, removal of the flags from whole patches, but not from individuals within patches, reduced pollinator visits. Chemical analysis suggested that the flag leaves' purple color is due to a high content of anthocyanin. Comparison of reflectance data for flags and leaves suggest that they can be visually discriminated by both pollinators and herbivores. Finally we have also looked into
the biomass 'cost' of the flag and concluded that it is probably negligible. Our results shed
light on visual based selection for extra-floral traits by pollinators and herbivores.

Heritability of floral volatiles and pleiotropic responses to artificial selection in
Brassica rapa (52051)

Pengjuan Zu, Florian Schiestl, Wolf Blankenhorn.

*Institute of Systematic Botany, University of Zurich; Institute of Systematic Botany, University of Zurich; Institute of Evolutionary Biology and Environmental Studies, University of Zurich.*

Plants produce a large diversity of volatile organic compounds that serve fundamental
functions such as pollinator attraction and herbivore deterrence. Plant volatile emission is
often highly variable and sensitive to environmental factors. To date, nothing is known about
heritability of plant volatiles, and whether individual compounds can evolve independently or
merely in concert with the whole volatile bouquet. To fill this gap in our understanding of
plant volatile evolution, we conducted bi-directional artificial selection on four target floral
volatiles representing four main chemical groups to estimate heritability and correlated
pleiotropic responses in fast cycling Brassica rapa. The realized heritability of the four target
volatiles ranged from 20% to 45%, as estimated from the “high amount” selection lines. The
average narrow-sense heritability of all 13 analyzed floral volatiles was 18% based on parent-
offspring regressions. There were pleiotropic effects of the selected volatile compounds on
other volatiles, on flowering time, and on some morphological traits. We found that the whole
floral scent bouquet changed even when there was selection on only single compounds. Our
study demonstrates that floral scent can evolve fast under phenotypic selection, but this can
come with additional correlated responses in traits that are not direct targets of selection.

# Are florivores agents of selection on floral colour? Review and Synthesis (51743)

Mahua Ghara, Yuval Sapir.

Tel Aviv University.

Colour in flower is an advertising signal, important to visually attract pollinator which in turn acts as an agent of selection on colour. Floral tissues such as petals, style, pollen, or ovules are consumed by insects (florivores) that may use colour to visually orient themselves to host. Florivores cause loss of fitness directly through consumption of gametes (pollen and ovules), and indirectly through alteration of signals important for pollinator attraction. Florivores are likely to impose selection on floral colour. We systematically reviewed available literature for evidences on pollinator- and florivore-mediated selection on floral colour, and for evidences on selection mediated by interaction between pollinators and florivores. Although
publications on pollinator-mediated selection were abundant, the role of florivores as agent of selection on floral colour remained relatively uninvestigated. A few studies provided evidence for florivores as agents of selection and some studies that failed to provide evidence for pollinator-mediated selection alluded to the possibility of selection mediated by florivores. The review summarizes the studies on florivore-mediated selection on floral colour, and suggests a frame-work to estimate the role of florivores in floral colour evolution. A possible cause for such shortage in studies on florivore-mediated selection, as compared to pollinators is discussed.

# Multiple morphological and behavioural modifications converge into a function that promotes invasion and diversification within a new adaptive zone (52191)

Antonin Crumière, Abderrahman Khila.

IGFL.

Evolutionary key innovations may open new ecological opportunities and facilitate adaptive radiations. However, the adaptive value of key innovations during initial stages of the colonization of new niches and genetic mechanisms underlying their emergence are rarely established. The Gerromorpha, a monophyletic group of semi-aquatic Heteroptera, transited from terrestrial life to life on the water surface, and radiated into remarkable forms that colonized a vast array of sub niches. Using phylogenetic mapping, we discovered that the transition to water surface life is associated with an increase in the frequency of leg strokes and an increase in leg length which is exploited by Gerromorpha to cover larger stroke amplitudes during water surface locomotion. The combined modification in these biomechanical parameters contributes to increase locomotion efficiency compared to exclusively terrestrial relatives. The emergence of these traits at the base of the Gerromorphan phylogeny coincides with the novel deployment of the Hox gene Ultrabithorax in the second thoracic segment. Using RNAi knockdown we highlight the importance of Ubx in the emergence of these traits and the role of fluid substrate as a selective force in the evolution of Gerromorpha. Therefore, evolutionary changes in highly pleiotropic genes can generate multiple discreet phenotypic changes, which can have a spectacular impact on organismal ecology and diversification.

# Natural Arabidopsis BRX Loss-of-Function Alleles Confer Root Adaptation to Acidic Soil (52240)

Christian Hardtke.

University of Lausanne.
To understand gene action at the cellular, tissue and organismal levels is the ultimate goal of developmental biology and can connect to ecological-evolutionary aspects through analysis of corresponding natural genetic variation. In our lab, we have isolated a regulator of root growth vigor in Arabidopsis thaliana named BREVIS RADIX (BRX) through the natural variation approach. Although generally highly conserved, hyperactive as well as loss-of-function BRX alleles exist in nature. A physiological feature of brx null mutants, proton pump hyperactivity, could explain their occurrence, because on overly acidic media or soil this feature confers more robust growth and increased fitness as compared to wild type. In these conditions, the fitness advantage might over-compensate for the loss of root meristem growth, for which BRX is essential. In summary, the existence of independently maintained brx loss-of-function alleles in nature and their association with low pH soils supports the notion that they are advantageous in acidic soil pH conditions. Physiological assays based on brx characteristics now enable us to map other genes that confer adaptation to acidic soil and to rapidly identify their causal allelic variants through next generation sequencing approaches.

**The genomic architecture of adaptation and speciation in ecologically
divergent forest trees (Populus spp.) (52358)**

Margot Paris, Stölting Kai N., Meier Cécile, Heinze Berthold, Castiglione Stefano, Bartha Denes, Macaya Sanz David, Gonzalez-Martinez Santiago, Lexer Christian.

University of Fribourg; Federal Forest Research Centre Vienna; University of Salerno; West Hungarian University; INIA-CIFOR.

Recent advances in sequencing technologies offer great opportunities to address the molecular basis of adaptation and ecological speciation. In Eurasia, several phenotypically differentiated forms within the ‘model tree’ genus Populus have diverged in the face of gene flow. Populus provides a promising model to explore the determinants of adaptation and divergence along a continuum, ranging from differentiated populations and phylogeographic lineages to divergent species with fairly strong postzygotic barriers. We report a whole genome sequencing effort involving multiple populations of Eurasian Populus alba and P. tremula including multiple post-glacial recolonization lineages within the former. We find a complex genomic architecture of adaptive differentiation from both, standing genetic variation and new mutations. In Central European P. alba alone, screening of 14 million sequence polymorphisms reveals 430 highly differentiated genes mainly linked to soil adaptation (e.g. ion transport, root development, and water stress response). High divergence between hybridizing species appears to be maintained by widespread coupling effects, whereas 4% of the studied genome windows do not exhibit any fixed between-species polymorphism. Some of these regions also exhibit intraspecific footprints of selection, thus suggesting that introgression contributes to the functionally important variation available for adaptation.
# The origin and spread of premating isolation driving incipient speciation in Mimulus (52401)

**Matt Streisfeld**, Sean Stankowski, James Sobel.

*University of Oregon; Binghamton University.*

Speciation is a continuous process that occurs across a broad range of spatial settings and scenarios. Yet, the historical events contributing to the origin and spread of traits that generate reproductive isolation are poorly understood. We elucidate the ecological genetic changes driving the early stages of divergence in a classic example of incipient speciation in Mimulus aurantiacus. Red- and yellow-flowered ecotypes are parapatrically distributed and partially isolated due to differences in habitat and pollinator behavior. However, postmating barriers are weak, resulting in gene flow across much of the genome and a narrow hybrid zone where ranges overlap. Nevertheless, a small set of loci remain differentiated, demonstrating the preliminary stages of genomic divergence. Indeed, six floral traits associated with pollinator isolation vary clinally in nature, providing strong evidence for divergent selection despite gene flow. Our molecular studies have revealed a cis-regulatory mutation in the MaMyb2 gene that is primarily responsible for red floral pigmentation. We show that this adaptive allele entered the red-flowered ecotype via introgressive hybridization with a more distantly related subspecies, a result that not only sheds light on the complex history of divergence but also the power of ecological adaptation to drive the early stages of speciation.

# Sexual isolation and the genetics of chemical cues involved in speciation in Heliconius butterflies (52450)

**Claire Mérot**, John Davey, Richard Merrill, Sarah Barker, Ene Leppik, Brigitte Frérot, Chris Jiggins, Mathieu Joron.

*ISYEB UMR 7205, Muséum National d'Histoire Naturelle, Paris; Department of Zoology, University of Cambridge; UMR 1392 iEES, INRA Versailles ; UMR 5175, CNRS-Centre d'Ecologie Fonctionnelle et Evolutive, Montpellier.*

Speciation with gene flow implies the evolution of reproductive isolation under selection favouring lineage differentiation. Understanding how divergent selection leads to speciation requires characterizing the ecological, phenotypic and genomic modalities of reproductive isolation. Heliconius butterflies are now an established example of ecological speciation driven by a “magic trait”, wing colour pattern, because a shift in this trait triggers disruptive selection for mimicry, as well as sexual isolation involving the same trait as a mating cue.

However, sibling species with similar wing patterns exist in sympatry, meaning that other traits maintain or accompany reproductive isolation. To understand the multidimensionality of speciation, we investigated Heliconius sister-species with similar patterns. Behavioural experiments show that pattern similarity interferes with mate location, yet species isolation remains strong due to mate choice based on short-distances cues. Chemical analyses on genitalia and wing scents demonstrated species-specific chemical signatures, suggesting
chemical communication participates to reproductive isolation. Using genome-wide RAD-mapping of interspecific crosses, we revealed the genetic architecture of pheromone profiles, analyzed it in the light of the genomic landscapes of divergence, and tested the linkage with other loci involved in speciation. This opens the possibility to explore the coupling and order of appearance of the different speciation modalities.

# Key Physiological Innovations during Colonizations of Fresh Water and Land (52488)

**Carol Eunmi Lee**, Seong-il Eyun, Marijan Posavi, Gregory Gelembiuk, Jane Remfert, Guy Charmantier, Mireille Charmantier-Daures.

*University of Wisconsin; University of Nebraska; Université de Montpellier.*

Arthropods are the most successful animal phylum on the planet, both in terms of number of species and total biomass. While arthropods evolved originally in the sea, they have become extraordinarily successful across an extremely wide range of habitats and ecological niches. Arthropods now dominate many marine, freshwater, hypersaline, and dry environments across the globe. While most marine invertebrates have no need to osmoregulate, invading freshwater habitats requires the active uptake of scarce ions, whereas invading land adds the additional challenge of also regulating water (at times to reduce water loss). In addition, challenges are imposed by the differences in physical properties between water versus air. Yet, arthropods have invaded freshwater and terrestrial environments multiple times independently. This talk discusses some key adaptations that occurred during the transitions from marine to freshwater to terrestrial habitats, based on results from laboratory selection experiments, comparative physiological studies, and genome sequence analyses. Evolution of ion transporter function appears to be critical for the transition from marine to freshwater habitats, and these functions appear to be concentrated in the legs in many arthropods. Additionally, across the phylum Arthropoda we observe curious gains and losses of chemoreceptor gene families in arthropod lineages.

# Distinct genetic mechanisms of parallel speciation in phytophagous ladybird beetles (52536)

**Kei Matsubayashi**, Victor Soria-Carrasco, Zachariah Gompert, Romain Villoutreix, Moritz Muschick, Akemi Togashi, Haruo Katakura, Hideki Ueno, Patrik Nosil.

*The University of Sheffield; The University of Sheffield; Utah State University; The University of Sheffield; The University of Sheffield; Hokkaido University; Hokkaido University; Niigata University; The University of Sheffield.*
Adaptation to similar environments can create new species and this process can occur repeatedly to result in replicate species pairs (i.e., parallel speciation). The genetic basis of this process is poorly understood but is assumed to usually occur by new pairs of species forming via divergence from a single shared ancestor. By combining genomic analyses with experimental estimates of several isolating barriers we found that parallel speciation in phytophagous ladybird beetle species involves distinct historical and genetic processes in different species pairs in Japan. In one geographic region a species pair was formed by divergence from a single common ancestor and specialization on different host plants. In contrast, in another locality a new species was formed by hybridization between two different closely related parental species. Although the latter case also involved host adaptation, it was facilitated by hybridization between the two parental species. The results indicate that individual species can contain much genetic variation due to variation derived from distinct ancestors, and that hybridization between populations can generate new highly distinct species even in the early stages of ecological speciation. The collective results illustrate complex origins of different species with a potential role for hybridization in facilitating this process.

## How do beneficial microbiomes form and adapt within mutualisms? (52278)

**Tabitha Innocent**, Mahmoud Al-Bassam, Morten Schiøtt, Douglas W. Yu, Matthew I. Hutchings, Jacobus J. Boomsma.

*Centre for Social Evolution, Department of Biology, University of Copenhagen; University of East Anglia, School of Biological Science, Norwich NR4 7TJ, Norfolk, England; Chinese Academy of Science, Ecology, Conservation and Environment Center (ECEC), Kunming Institute o.*

The fungus-farming attine ants live symbiotically with multiple species of antibiotic-producing actinobacteria. We know the diversity of bacterial species provides a diversity of antibiotics, thus maintaining long-term protection against pathogens that attack the ant's fungal mutualist. However, only one of these actinomycete species is vertically transmitted by the ants, so it has remained unclear how and at what life stages more diverse beneficial microbiomes are established by selective recruitment of additional actinomycete strains from the environment.

This is an important general problem: how do the dynamics of bacterial competition lead to the formation of a microbiome that benefits a host and mutualistic partner? While mutualisms between bacteria and other species are both abundant and influential (e.g. multiple insects, crop plants, coral systems), these systems tend to be difficult to experimentally manipulate in the lab. With the attine ant model we can empirically test the latest evolutionary theories on mutualism stability with ramifications well beyond this system.

In this light, I will present genomic and experimental data covering several genera of attine ants suggesting the ants promote interference competition among bacteria, and this competition favours beneficial actinobacterial communities.
# Mutualism in a community context: lessons from ants, aphids and their gut microbiomes (52797)

Aniek B.F. Ivens, E. Toby Kiers, Daniel J.C. Kronauer.

*The Rockefeller University, New York, USA; VU University Amsterdam, NL.*

Ant-aphid interactions are classic examples of interspecific cooperation. The ants depend on honeydew excreted by the aphids for sugar; the aphids depend on the ants for protection and hygiene. Such mutualistic interactions are inherently prone to destabilizing conflicts of interest. Several mechanisms can align the partners' interests, such as partner fidelity through reduced rates of aphid dispersal and partner choice based on honeydew quality.

Although historically regarded as two-species interactions, mutualisms are now increasingly recognized as complex multispecies networks. Using genetic barcoding, we show that an interaction of subterranean Lasius ants tending Prociphilus aphids in fact comprises a mutualistic community of multiple species of ants and aphids. Moreover, aphids harbor specialized endosymbiotic bacteria, which facilitate feeding on specific plants; likewise the ants' gut microbiome likely facilitates honeydew digestion.

In our experiments, we aim to identify the roles these microbes play in the mutualism's evolutionary stability. Their impact is potentially huge: by influencing honeydew quality, aphid endosymbionts can affect partner choice. Likewise, ant gut microbes can affect partner fidelity by determining on which aphids' honeydew the ants can feed and thus with whom they can associate. Including additional organisms can thus drastically change our understanding of the evolutionary ecology of mutualism.

# Colony fusion as a route to cooperation without kinship in ant supercolonies (52676)

Ea B. M. Hørsving, Louise S. Pedersen, Dóra B. Huszár, Luigi Pontieri, Jacobus J. Boomsma, Jes Søe Pedersen.

*Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15,.*

One of the most spectacular cases of cooperation among unrelated individuals is ant supercolonies, where large networks of interconnected nests may extend over hundreds, or even thousands, of kilometres without territorial aggression. Several species exclusively form supercolonies and always as genetically closed lineages that have emerged by budding from existing ones (fission). Alternatively, here we asked whether fusion of colonies has the potential to lead to the emergence of new supercolonies in the common red ant Myrmica rubra. We found that two colonies do not fuse only if they are both tight families headed by a single queen. All other M. rubra colony combinations always fused, even when the
geographic origin was as distant as Denmark and Finland (different haplotype groups). This
indicates that supercolony formation in M. rubra is more dependent on family structure than
genetic distance, and that multiple-queen colonies can expand in the habitat and merge.
Genetic evidence for mixed origins of supercolonies indicates that fusion indeed happens in
the field. These complexities suggest that there may be more than a single evolutionary route
to the paradoxical state of supercoloniality, and that colony fusion could lead to cooperation
without kinship in evolutionarily derived ant lineages.

Specialist and generalist oviposition strategies in butterflies: maternal care or precocious young? (52208)

Alexander Schäpers, Sören Nylin, Mikael Carlsson, Niklas Janz.

*Department of Zoology, Stockholm University.*

Herbivorous insects specialized on a narrow set of plants are believed to be better adapted to their specific hosts. Species with a broader diet breadth seem to pay a cost through decreased oviposition accuracy. Despite many studies investigating oviposition behavior we lack knowledge on how larvae cope behaviorally with their mothers' egg-laying strategies. We examined how five nymphalid butterfly species with different host plant ranges differed in female oviposition preference and in neonate larval behavior in several disadvantageous situations. We found a general synchrony between female and larval abilities, where species with more “caring”, discriminating females had larvae that were less able to deal with a suboptimal initial feeding site. Conversely, relatively indiscriminate females had more precocious larvae with higher abilities to cope with suboptimal sites. Remarkably, despite similarities between the tested species with similar host ranges, there were also striking differences. Generalist and specialist species can be found side by side in many clades, with each clade having a specific evolutionary history. Such clade-specific, phylogenetically determined preconditions apparently have affected precisely how a broad or narrow diet breadth can be realized.

Factors affecting the evolution of host-switching in infectious diseases (52407)

Alethea Wang, Magda Meier, Francois Balloux.

UCL; UCL; UCL.

Although new infectious diseases have become increasingly prevalent in the past several
decades, the underlying factors leading to their emergence remain unclear. Epidemics have
frequently been linked to pathogen host switching, but few studies have broadly examined the
overall prevalence of host switching across pathogen groups. Here, we examine how two
evolutionary factors - host taxonomic relatedness and pathogen host range - influence a
pathogen's ability to infect new host species. Although pathogens often infect closely related species, there are also many cases in which the original and new hosts are taxonomically diverse. Second, pathogens vary considerably in their host ranges, with some being specialists that only infect a single species and others capable of infecting hosts from a number of different taxonomic groups. We conducted a comprehensive literature review of ~550 bacterial pathogens of humans and animals to quantify whether host taxonomic relatedness and breadth of host range are important factors underlying the potential for pathogen host switching. This understanding will improve our ability to predict, prevent and control future disease outbreaks.

## The long reach of a tapeworm parasite in its social host (52951)

**Sara Beros**, Evelien Jongepier, Felizitas Hagemeier, Susanne Foitzik.

*Institute of Zoology, Department of Evolutionary Biology, Johannes Gutenberg University.*

Parasite-induced alterations are well-known on the individual level, but the consequences of parasite infections for social groups are less clear. Manipulative parasites with complex life cycles could extend their influence to non-infected group members by chemical or behavioural manipulation to ensure their own survival and transmission. An infection with the tapeworm Anomotaenia brevis induces multidimensional changes in its intermediate host, the ant Temnothorax nylanderi. Despite having a deviant chemical profile that would usually lead to social rejection, infected ants are tolerated and well-cared for in their colonies, as evident in their increased survival rate. Here, we tracked infection-mediated effects by manipulating the composition of ant colonies through addition and removal of infected workers, and determined colony aggression. Our results reveal that the presence of infected ants clearly influences the colonies' response to intruders. Parasitized colonies behaved less aggressive towards conspecifics, and this change was based on a lower aggression in non-infected ant workers. We argue that this lower aggression might be the outcome of behavioural manipulation and could ensure the care for infected workers, consequently increasing parasite fitness. In summary, individual parasite infections can have far-reaching consequences in social groups, hereby influencing the behavioral performance on the colony level.

## Wing pigmentation and immune response in the Glanville fritillary butterfly (51704)

**Elena Rosa**, Marjo Saastamoinen.

*University of Helsinki.*

Melanin production in insects is typically involved in pigmentation and immune response, and both of these traits depend on the phenoloxidase enzyme pathway. During attacks by
exogenous pathogens, encapsulation response is activated, resulting in clotting and melanisation of the foreign bodies. In butterflies, melanin production is important in the cuticle and adult wing pigmentation, and it has a key role in thermoregulation. However, as melanin production is costly, trade-offs among competing life history traits are expected, especially under restricted resource conditions.

In Finland, the Glanville fritillary butterfly occurs in its northern range limit and is restricted to the Åland archipelago, where a conspicuous variation in wing darkness among individuals has been observed. Our aim is to investigate within and among population level variation in the relationship between immunity and pigmentation. Darker patterns are predicted to be influenced also by developmental conditions: individuals under cool environmental conditions are expected to be darker as a predictive adaptive response to allow faster heat absorption and increased activity under those conditions. However, immune challenge during early life may activate melanin production and influence its allocation to wing patterns, or to adult immune response.

# Field estimates of parentage reveal sexually antagonistic selection on body size in a population of Anolis lizards (51824)

**Katie Duryea**, Patrick Bergeron, Zachary Clare-Salzler, Ryan Calsbeek.

Lund University; University of Sherbrooke; University of Montana; Dartmouth College.

Sexual dimorphism evolves when selection favors different phenotypic optima between the sexes. Such sexually antagonistic selection creates intralocus sexual conflict when traits are genetically correlated between the sexes. We investigated sexually antagonistic selection on body size in the brown anole lizard, Anolis sagrei. Brown anoles are highly sexually dimorphic: males are on average 30% longer than females and 150% more massive in our study population. Viability selection on body size is sexually antagonistic and directional selection favors larger males whereas stabilizing selection constrains females to remain small. Here, we measure reproductive components of fitness over three generations in a population of brown anoles. We estimated the number of offspring produced by an individual that survived to the following year, a measure of individual fitness that includes aspects of both individual reproductive success and offspring survival. Using this measure of fitness, we found directional selection on male body size, consistent with previous studies of viability selection. However, selection acting on female body size varied among years, including periods of positive directional selection, stabilizing selection, and no selection. Thus, selection acts differently in the sexes through both survival and reproduction and sexual conflict appears to be a persistent force in this species.

# Identification and characterisation of sexually antagonistic loci in Drosophila melanogaster (51842)
**Mark Hill**, Ted Morrow, Kevin Fowler, Max Reuter.

*University College London; University of Sussex.*

Divergent evolutionary interests between the sexes generate sexually antagonistic selection, where opposing trait values are selected in males and females. However, a response to these selective pressures is constrained by the sexes' shared genome, leading to 'intralocus sexual conflict' (IASC). Despite our increasing understanding of the taxonomic prevalence of IASC and the traits affected, the identity of antagonistic loci remains almost entirely unknown. Here, we present the results of a study addressing this question. We identified antagonistic loci in D. melanogaster by combining genomic data from a set of sexually antagonistic haplotypes with an evolve-and-resequence experiment. Both studies identify well-supported candidate loci and significantly overlapping sets of genes. Enrichment analyses show that antagonistic genes are predominantly involved in developmental and regulatory processes and, interestingly, include a significant number of genes involved in the sex-determination cascade. Collectively these studies represent the first detailed information regarding the genetic basis of IASC and provide a good foundation for studying the functional genetics of sexual antagonism and elucidating its evolutionary dynamics.

Session 2 THU GEN C 4

**Male-male competition in the pistil causes rapid sexually antagonistic evolution in a plant and a correlated response on a mating-system related floral trait (51995)**

**Åsa Lankinen**, Sofia Hydbom, Maria Strandh.

*Swedish University of Agricultural Sciences, Sweden; Lund University, Sweden.*

Adaptive evolutionary change in response to sexual selection and sexual conflict can be surprisingly fast in animals. In plants, however, such knowledge is limited, as experimental evolution studies manipulating the strength of sexual selection have not been conducted. In Collinsia heterophylla, a 'mixed-mating' annual that combine outcrossing and self-pollination, early fertilizations are associated with female fitness costs, which is in accordance with a sexual conflict over timing of pistil receptivity to pollen. To test how sexual conflict influences trait evolution we conducted artificial selection on pollen by creating monogamous and polyandrous lines (crossed with one or two pollen donors, respectively, at early floral stages). After four generations of artificial selection we found increased pollen competitive ability and enhanced female fitness costs in the polyandrous selection line compared to the monogamous selection line and a control line, showing rapid sexually antagonistic evolution of pollen. Additionally, we found evidence for a correlated positive effect on timing of anther-stigma contact, a trait that determines timing of self-pollination. In conclusion, our study suggests that artificial sexual selection on pollen can lead to rapid evolutionary change in plants, female fitness costs and correlated effects on mating system-related traits.
## Sex biased expression as a sexually antagonistic trait (52078)

Paris Veltsos, Yongxiang Fang, Andrew R Cossins, Rhonda R Snook, Michael G Ritchie.

*Centre for Biological Diversity, University of St Andrews; Centre for Genomic Research, University of Liverpool; Centre for Genomic Research, University of Liverpool; Animal and Plant Sciences, University of Sheffield; Centre for Biological Diversity, University of St Andrews.*

Sexually antagonistic traits such as growth rates, colouration or immunity are often under sexual selection. The availability of transcriptomic data has led to comparisons of gene expression levels under different sexual selection treatments, linking gene expression and sexually antagonistic trait studies. We have experimentally manipulated the strength of sexual selection, by either enforcing monogamy or exposing females to higher than natural number of male partners, for over 150 generations in lab populations of Drosophila pseudoobscura. Such manipulation may influence one sex more than the other and can result in the inversion of sex bias for some genes. By employing replicated sampling over two tissues and mating statuses we demonstrate that, in most cases, the expression of sex biased genes responded to experimental sexual selection more than unbiased genes. However the direction of the shift in gene expression was difficult to predict and sensitive to both tissue and mating status. We conclude that sex biased gene expression can be considered a sexually antagonistic phenotype, but the direction of change in response to sexual selection can vary within the same organism.

Session 2 THU GEN C 4

## Sexual conflict and sex-biased gene expression throughout development (52134)

Fiona Ingleby.

*University of Sussex.*

Sexual dimorphism offers a potential resolution to intralocus sexual conflict, by allowing males and females to express their optimum trait phenotype when fitness optima differ between the sexes for a shared trait. As most of the genome is shared between the sexes, sex-biased gene expression is likely to account for most sexual dimorphism. Our research examines how sex-biased gene expression relates to sex-specific fitness throughout development as well as across different genotypes, therefore examining developmental and genetic sources of variation in sexual conflict. Using data from sex-specific fitness assays in Drosophila melanogaster, I show changes in sexual conflict between larval and adult stages, and show genetic variation for sexual conflict. I also use preliminary gene expression data from an RNA-sequencing experiment to begin to relate sex-specific fitness to patterns of sex-biased gene expression at each developmental stage.

Session 2 THU GEN C 4
# Evolution of haploid selection in predominantly diploid organisms (52393)

Sarah P Otto, **Michael F Scott**, Simone Immler.

*University of British Columbia; Uppsala University.*

Diploid organisms shape the extent to which their haploid gametes and gametophytes experience selection. While animals are thought to experience only mild selection in the haploid stage, plants often experience strong haploid selection. When should parents limit exposure of gametes to haploid selection and when should they strengthen this selection? We develop mathematical models that consider the "selective arena" within which male gametes or gametophytes (sperm or pollen) compete for fertilization, examining how this selective arena evolves when controlled by the mother or by the father. In the presence of deleterious mutations, increased haploid selection purges the gamete pool and leads to higher quality offspring. Thus, mothers should maximize selection in the haploid phase as long as all their eggs/ovules can still be fertilized. Fathers, however, are primarily selected to maximize the proportion of offspring that they sire. Therefore, fathers often evolve to mask haploid expression, creating the potential for parental conflict. Furthermore, we include sex chromosome linkage and the effect of alleles that are not strictly deleterious. That is, alleles can have different fitnesses in males and females (sexually antagonistic selection) or in haploids and diploids (ploidally antagonistic selection), which modifies the optimal intensity of the selective arena.

Session 2 THU GEN C 4

# Sexually antagonistic selection in canaries not generated by testosterone-related intralocussexual conflict (52841)

**Arne Iserbyt**, Marcel Eens, Wendt Müller.

*University of Antwerp.*

A current debate exists on the extent to which males and females constrain each other's evolution. On the one hand intersexual genetic correlations may cause a fundamental evolutionary problemwhen selection favors sex-specific phenotypic optima. On the other hand genetic mechanismsmay evolve that resolve this intralocus sexual conflict by decoupling developmental pathways inmales and females. Circulating testosterone (T) levels received increased research interest in thiscontext, given its important role in mediating suites of physiological, morphological andbehavioural traits and given its marked differential fitness effects in male and females. Here, weapplied a full-sib (brother/sister) comparison in a pedigreed canary population to continue thisdebate. We show that parental fitness is negatively correlated between siblings, indicatingsexually antagonistic selection. Furthermore, plasma T levels of brothers and sisters werepositively correlated, indicating a significant intra-sexual genetic correlation with a heritablecomponent (h²) estimated at 0.41 ± 0.31. However, T levels could not explain the fitness variationbetween siblings, contrasting the hypothesis of intralocus sexual conflict. The mechanism(s)underlying sexually antagonistic selection yet remain to be identified.
# DNA methylation in the clonal raider ant Cerapachys biroi (52304)

**Romain Libbrecht**, Peter Oxley, Laurent Keller, Daniel Kronauer.

*Rockefeller University; University of Lausanne.*

Division of labor is at the root of the ecological success of insect societies, yet the mechanisms regulating reproduction and behavior are not fully understood. The clonal raider ant Cerapachys biroi has no distinct queen and worker castes, and is characterized by an alternation between reproductive phases (ants lay eggs inside the nest) and brood care phases (ants do not lay eggs but nurse the brood and forage for food). The opportunity to compare queen-like (reproductive phase) and worker-like (brood care phase) individuals, combined with the possibility to control for age, experience and genetic background (all known to influence reproduction and behavior), makes C. biroi a great model system to study division of labor. In the past few years, there has been a growing interest in the role of epigenetic mechanisms (e.g. DNA methylation) in division of labor. Our aim is to properly investigate the role of DNA methylation in regulating reproduction and behavior in C. biroi, by comparing whole-genome DNA methylation patterns (using bisulfite sequencing) between brains of individuals collected in reproductive and brood care phases. This project also provides important insights into the function and mode of action of DNA methylation in insects.

# Correlated experimental evolution of behaviour and life history in Drosophila (52373)

**Katja Hoedjes**, Martin Kapun, Bas Zwaan, Thomas Flatt, Laurent Keller.

*University of Lausanne; Wageningen University.*

Selection on one trait often results in changes in other, seemingly unrelated traits, due to pleiotropy or linkage. For example, correlated responses between behaviour (learning ability) and life history (longevity) have been reported in the fruit fly, Drosophila melanogaster. However, the molecular basis of correlations between behaviour and life history remains poorly understood. To begin to uncover these mechanisms we have employed experimental evolution (EE) in the fruit fly. We used two independent selection regimes: populations adapted to poor larval nutrition and populations that were selected for reproduction at old age. In both selection regimes significant evolutionary responses in life history traits were observed, including in development time and longevity, with little evidence for interactions between the regimes. To examine correlated behavioural responses, we measured learning and locomotory behaviour in adults of the EE populations. We also sequenced pooled genomic DNA samples of 250 individuals per EE population and analyzed these genomes for variation in single nucleotide polymorphism frequencies. This approach allows us to identify candidate
genes or pathways that might underpin correlations between learning and locomotion and the
observed differences in life history.

The social niche experienced early in life influences the behavioural phenotype
(52467)

Valentina Balzarini, Michael Taborsky, Joachim G. Frommen.

Behavioral Ecology, Institute of Ecology and Evolution, University of Bern, Switzerland.

According to the social niche theory of animal personality, multidimensional social options select for fine-tuned specialisations due to multi-niche frequency dependence. In addition to negative frequency dependence stabilizing the coexistence of alternative behavioural tactics, the development of different personalities is triggered by positive feedback favouring behavioural consistency due to benefits of specialisation and the avoidance of the costs of switching between strategies. This hypothesis has been rarely tested; a critical test requires a system that is characterized by a combination of high social complexity with experimental accessibility. The cooperatively breeding cichlid Neolamprologus pulcher combines these requirements. We studied the influence of individual social experience during ontogeny on the development of personality traits in these highly social fish. We experimentally assigned 14 days old fry to one of two alternative roles, either to be subordinate or dominant to a group of 4 unrelated fry. We kept focal fish in their respective roles for 3 months and monitored their social behaviour weekly. Subsequently, we tested their personality traits, including social interaction, exploration and helping propensities. Our data reveal that early life experience in an experimentally assigned social role affects the entire behavioural phenotype of an individual throughout extended periods of their life.

Genomic changes associated with behavioural plasticity: selection for improved learning behaviour (52472)

Maartje Liefting, Ken Kraaijeveld, Cecile Le Lann, Bregje Wertheim, Jacintha Ellers.

VU University Amsterdam; Université Rennes 1; University of Groningen.

Learning is considered a form of behavioural plasticity through which an organism can adjust
its performance to changes in the environment. Evolution of learning behaviour and memory
dynamics of species is highly context dependent, giving rise to inter- and intraspecific
variation in learning rates. Despite significant progress in unravelling the neurobiology and
memory pathways underlying such variation, our understanding of the genetic support of
variation in cognitive abilities and the relevance in an evolutionary ecological context remains
incomplete. In addition, little is known on how selection on one aspect of learning may result
in correlated evolution of other cognitive skills. We performed an artificial selection
experiment with the parasitoid wasp Nasonia vitripennis to improve learning of host-associated visual cues in females. Selection lines readily evolved improved learning skills, which also extended to other (olfactory) cues, suggesting general learning ability was targeted by selection. These improved cognitive skills of the selection lines even extended to male learning. Subsequently, we used high throughput sequencing to characterize changes in the genome associated with improved learning. SNP analysis identified multiple genomic changes associated with cognitive skills, and we discuss genes within these regions that form putative targets of selection.

## Maladaptive reproductive investment and behavioral variation in urban habitat (52607)

**Virginie Demeyrier**, Arnaud Grégoire, Marcel Lambrechts, Anne Charmantier.

*Cefe UMR 5175 - Cnrs.*

Increasing urbanisation imposes novel constraints for many organisms. While urbanisation is considered as an extreme situation where humans significantly influence wildlife, it can also provide opportunities to study mechanisms of adaptation. Within the artificial cocktail present in towns, artificial cavities are clearly potential evolutionary-traps for cavity-nesting birds. In this study, we performed an experiment where urban insectivorous cavity-nesting great tits (Parus major) were offered three nest-box sizes, covering the natural cavity range, in the city of Montpellier, France. Following a four-year monitoring of breeding phenology and using measures of anthropogenic perturbations and resource abundance, we show that great tits are more attracted to, lay larger clutches in, and finally produce fewer fledglings in, large rather than smaller artificial cavities. Increasing family size according to cavity size has previously been described. However, our results reveal that this strategy is maladaptive when large artificial cavities are placed in urbanized invertebrate-poor environments. Additionally to this experiment, open-field trials over two years allowed to compare great tit personalities in a deciduous forest near the city of Montpellier and along an urban gradient within the city. The results show contrasted personalities in rural versus urban environments and shed light on behavioural adaptation and maladaptation in an urban context.

## The role of state-behavior feedbacks in explaining adaptive personality differences (52710)

**Maria Moiron**, Kimberly J. Mathot, Niels J. Dingemanse.

Max Planck Institute For Ornithology; Royal Netherlands Institute for Sea Research; Ludwig-Maximilians University of Munich.
In recent years it has become widely accepted that individuals within single populations often exhibit consistent differences in behavior across contexts and over time (called ‘animal personality’). However, it is much less evident how behavioral consistency can be explained from an adaptive viewpoint. State-behavior feedback loops have been proposed as an evolutionary explanation for personality-related differences. The feedback mechanism between state and behavior exists because an individual’s state affects its optimal behavior, which in turn affects its state. This feedback dynamics has been theoretically well-developed but never empirically tested. Here we first provide a statistical framework based on repeated measures and multi-level random regression modelling that enables one to capture variation in state-behavior feedbacks. Next, we experimentally explore feedback loops between sampling (information acquisition) and body condition that may explain why individuals differ in sampling behavior using wild passerine birds (great tits) as a model species. We present data on the occurrence of between- and within- individual variation in sampling; and we provide an empirical test of how positive feedback loops lead to within individual state-behavior covariance and between individual positive intercept-slope correlations of temporal reaction norms, while negative feedback loops lead to the opposite outcome.

## Behavioural interactions of a planktonic crustacean with pond sediments
(52929)

Roberto Arbore, Alexandra Mushegian, Jason Andras, Dieter Ebert.

*University of Basel; Mount Holyoke College.*

Planktonic species differ in the degree to which they interact with the bottom sediment surfaces. Some species, although primarily pelagic, might display important connections with the benthic habitat. The freshwater crustacean Daphnia magna can adopt a sediment browsing behaviour, alternative to suspension filter feeding. Such behaviour, while conferring the ability to exploit benthic food sources, also increases the exposure to multiple risks as, for instance, infection from sediment spore banks and benthic predation. We found genetic variation for this behaviour within an experimental population (F2 recombinant panel) and between clones from natural populations of different ecological contexts (e.g. presence/absence of fish predation). A QTL analysis provided evidence for a complex genetic architecture underlying this behavioural trait. In order to get further insights on the nature of the selective pressures possibly acting on the evolution of this behaviour, we performed a series of experiments using clones with high and low browsing activities. Here we examine a scenario involving both costs (e.g. risk of parasite infection) and benefits (e.g. foraging opportunities, microbiota acquisition) associated with sediment browsing and its environmental effects (e.g. conspecific infection risk due to sediment bioturbation).

## Coevolution of genetic variance and species' range in a changing environment
(52491)
**Jitka Polechova**, Nick Barton.

IST AUSTRIA.

As the environment changes in time, species change their range: they adapt, diversify or perhaps go extinct. The standing genetic variation of a species is crucial for its adaptation to changing conditions, and gene flow across a phenotypic gradient can maintain a large genetic variance. Yet, most studies of adaptation to a changing environment either neglect the effect of gene flow, or assume that genetic variance is constant. We model the joint population dynamics and evolution of the trait mean and its variance, via change in allele frequencies. When mutation contributes little to the standing genetic variation, a straightforward extension of the theory for panmictic populations predicts the critical rates of spatial and temporal change that a population can track. Large populations adapted to a steep environmental gradient can also adapt to a faster temporal change, because gene flow across a steep phenotypic gradient generates high local genetic variance. Further, we show that when the number of mutations per generation in the selected loci is high, ‘cline reversals’ (paired such that gradient in trait mean does not change) can increase the genetic variance fast enough to prevent demographic collapse due to maladaptation, and hence allow adaptation to a faster temporal change.

Session 2 THU POL A 32

# The role of sex and recombination in evolutionary rescue (52499)

**Hildegard Uecker**, Joachim Hermisson.

IST Austria; University of Vienna.

Environmental change, if severe, can drive a population extinct unless the population succeeds in adapting to the new conditions. How do sexual reproduction and recombination affect the survival chances of an endangered population? We consider the probability of evolutionary rescue after a sudden deterioration of the environment when survival of the population is contingent on mutations at multiple (two) loci or the formation of mutant homozygotes. Such situations arise, for example, in combination drug therapy or the application of herbicide mixtures. We compare the rates of rescue in random mating, selfing, and clonal populations under these conditions. Recombination and likewise segregation during sexual reproduction generically have two opposing effects: they generate and they break up favorable gene combinations. We investigate how the population dynamics affect the interplay of these two effects and consequently the rate of adaptation from standing genetic variation and de-novo mutations. We find that, even in the absence of density-dependent fitness, a fast eradication of the wildtype population can enhance rescue in a sexually reproducing population. On the other hand, recombination and segregation can prevent rescue when the wildtype disappears slowly.
# Environmental marginality and the evolutionary potential of peripheral populations in Arabidopsis lyrata (52568)

**Julie Lee-Yaw, Yvonne Willi.**

*University of Neuchatel.*

Theoretical models of species' geographic range limits are often premised on environmental gradients, with species experiencing increasingly marginal conditions towards the edge of their range. Range limits arise where adaptation to these conditions ultimately fails. However, whether the range limits of most species conform to this scenario remains unclear. Using spatial data and ecological niche models we explore these assumptions in North American Arabidopsis lyrata. Specifically, we ask whether peripheral populations occupy sites of low suitability relative to more central populations and whether range limits coincide with predicted niche limits. We further ask whether genetic diversity and the transition from outcrossing to selfing (restricted to peripheral populations in this system) is associated with particularly poor-quality habitat, thus testing the link between range position, habitat quality and demography. Our results suggest that latitudinal range limits in this system are well explained by the abiotic environment. Peripheral populations occupy regions of low suitability relative to more central populations, with genetically impoverished and selfing populations at the range edge occupying some of the lowest-quality sites. We will discuss the implications of these results for our understanding of the evolutionary potential of peripheral populations.

# Evolution of seasonal timing in a changing world: how empirical evidence and phenological models can help us to forecast the rate of adaptation (52721)

**Lucia Salis, Marcel Visser.**

*Netherlands Institute of Ecology (NIOO-KNAW).*

In a changing world, species need to adapt to their new environment. In the winter moth, the synchronization between timing of egg hatching and the bud burst of its food plant, the oak, has been disrupted by climate change. Using both long-term (18 years) observational data and experiments we show that timing of egg hatching has changed genetically, resulting in closer synchrony of egg hatching with oak bud burst. We explore using an eco-evo-devo framework what the limitations are of this genetic adaptation. We first developed a novel phenological model that accurately describes how an insect's developmental rate is affected by the interaction between developmental state and temperature. Accounting for this interaction improved the predictive power of the model and therefore contributed to a better understanding of the mechanisms underlying insect development. Next, we use this model to study the genetic variation in the model's parameters and to test whether there is additive genetic variation in these parameters, and thus whether these parameters can be altered by selection. As temperature are forecasted to continue increasing, eco-evo-devo studies that couple empirical findings with phenological models offer a unique opportunity to unravel the potential of future insect's adaptive responses to climate change.
# From genes to ecosystems: the molecular mechanisms of eco-evolutionary feedbacks from rapid adaptation of herbivore consumers to nutrient limitation (52843)

**Spiros Papakostas**, Steven Declerck.

*University of Turku; Netherlands Institute of Ecology.*

Humans alter biogeochemical cycles of essential elements such as phosphorus (P). Prediction of ecosystem consequences of altered elemental cycles requires integration of ecology, evolutionary biology and the framework of ecological stoichiometry. We studied micro-evolutionary responses of populations of a herbivorous rotifer species to P-limited food and the potential consequences for its population demography and for ecosystem properties. We subjected field-derived, replicate rotifer populations to P-deficient and P-replete algal food, and studied adaptation in common garden transplant experiments after 103 and 209 days of selection. We quantified about 30000 transcripts using next-generation sequencing and 1000 proteins using high-resolution mass spectrometry. When fed P-limited food, populations with a P limitation selection history suffered 37% lower mortality, reached twice the steady state biomass, and reduced algae by 40% compared to populations with a P-replete selection history. Adaptation involved no change in rotifer elemental composition but reduced investment in sex. Selection history had a profound impact on the expression profile of the rotifers and several transcripts and proteins showed an expression profile specific to each condition pointing towards the molecular basis behind those adaptations. We demonstrate potentially strong eco-evolutionary feedbacks from shifting elemental balances to ecosystem properties and study the underlying functional molecular mechanisms.

# Estimating evolutionary potential in the wild : role and stability of the G matrix (51978)

**Céline Teplitsky**, Stéphane Chantepie, Anders P. Moller, Shinichi Nakagawa, Florentino de Lope, Lars Gustafsson, James A. Mills, Nathaniel Wheelwright, Anne Charmantier.

Département Ecologie et Gestion de la Biodiversité UMR 7204 CNRS / MNHN / UPMC, Muséum National d'Hi; Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, Grenoble I, BP 53, 38041 Gr; Laboratoire d'Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, F-91405 Orsa; Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand ; Department of Zoology, Biology Building, University of Seville, E-41012 Seville, Spain; Department of Animal Ecology, Evolutionary Biology Center, Uppsala University, SE75236, Sweden; 10527 A Skyline Drive, Corning, New York 14830, USA; Department of Biology, Bowdoin College, Brunswick, Maine 04011, USA; Centre d'Ecologie Fonctionnelle et Evolutive UMR 5175 CNRS, F-34293 Montpellier, France.
Global environmental change represents a major threat to biodiversity today. The habitats of species are being modified at a fast rate, raising an important question: will populations manage to adapt to the new conditions? One strong constraint on microevolutionary responses is the fact that traits within an organism are not free to evolve independently, but form integrated units. There is growing evidence that the genetic correlations between traits can slow down the rate of adaptation in wild populations. However, the importance of such constraints will depend on their stability, i.e., if genetic correlations are changing rapidly, the G matrix should not represent a strong constraint on evolutionary responses and evolutionary responses would be difficult to predict.

We investigated the stability of the G matrix across five bird species, comparing conditional evolvability and autonomy over 5 year time periods. These variables can be estimated using animal models (MCMCglmm software) on long term data sets of wild bird populations for which detailed pedigrees are available. The G matrix for morphological traits is stable in all the populations considered. We compare this to expectations based on estimates of selection within the populations, and assess whether G is aligned with selection.

# Adaptation lags in bet-hedging traits during periods of climate change (52047)

**Tom JM Van Dooren.**

*Institute for Ecology and Environmental Sciences iEES Paris.*

Bet-hedging occurs as an adaptation to unpredictable environments. It is nature's insurance policy against uncertain events. Our theories assume that such adaptation is to an unpredictably fluctuating but stationary environment. There are little or no predictions on how such traits would evolve during periods where environmental variables are not stationary, but change with trends in means and variances. With such trends, adaptive states are what one would find eventually if evolving populations would adapt to repeated sampling from the instantaneous state of the probability distributions of environmental parameters. Adaptive lags are then the differences between such adaptive states and the actual state of a population. By means of the main textbook example of bet-hedging evolution, namely that of an evolving probability of germination in annual plants with a seed bank, I show that gradual unidirectional change in environmental parameters can lead to an intermittent window where bet-hedging is not adaptive. The adaptive lag in the actual response in germination probability can then reverse in sign: first plants germinate too little. When bet-hedging has become adaptive again, they germinate too much.

I extend my example with an evolving plastic germination probability, and scenarios of environmental change with a tipping point.

# An island model for unraveling adaptive history: Cape Verde Arabidopsis (52468)
Andrea Fulgione, Stéphanie Arnoux, Joachim Hermisson, **Angela Hancock**.

*University of Vienna; Gregor Mendel Institute; University of Vienna; University of Vienna.*

Islands have been central to evolutionary biology since Darwin and Wallace. They represent natural laboratories, where fundamental principles of the evolutionary process can be revealed. We combine a tractable island system and a well-studied model organism to unravel the historical route to local adaptation in an extreme environment.

A single Arabidopsis sample was collected 30 years ago in the Cape Verde Islands, a climatic extreme in the Arabidopsis species distribution. Due to its surprising location and phenotypic divergence, the resulting line (Cvi-0) is an enigma to the Arabidopsis community. Over the years, Cvi-0 has been the subject of extensive QTL mapping efforts and functional follow-up analyses, so that we have a wealth of information about the genetic basis of its intriguing phenotypic divergence. This backdrop provides an ideal opportunity to access the specific events that led to local adaptation in this population. To this end, we collected and sequenced population samples from Cape Verde to reveal a striking signature of strong positive selection on pleiotropic functional variants as well as parallel adaptation across islands. Our study design provides a framework for combining knowledge from trait mapping, population genetics, functional variant identification, and field studies of natural populations to characterize the details of adaptive dynamics in nature.

# The Genetic Architecture of Recombination Rate Variation in Drosophila melanogaster (52479)

**Nadia Singh**, Chad Hunter.

*North Carolina State University.*

Meiotic recombination is an essential biological process, necessary for proper chromosome segregation in many organisms. Despite this critical function, rates of recombination are highly variable within and between populations and species. The genetic architecture of this variation remains poorly understood, especially in the model organism Drosophila melanogaster. We sought to identify the genetic basis of recombination rate variation using whole genome association mapping. We leveraged the Drosophila Genetic Reference Panel for this purpose and measured rates of meiotic recombination on two chromosomes in 205 fully sequenced inbred lines using a classical genetic approach. We scored over a 500,000 progeny and revealed 2-3 fold variation in crossover frequency among lines. Much of this variation is genetic, and we used genome-wide association mapping to identify genetic factors contributing recombination rate. We used RNAi, mutant analysis, and expression assays to functionally confirm a subset of candidates revealed by this approach. Our results thus provide comprehensive insight into the scale and scope of population-level variation in recombination rate in Drosophila and the first insight into the genetic architecture of population-level variation in recombination rate in this model system.
# Tracking genomic changes during rapid life history evolution (52853)

**Nina O. Therkildsen**, Stephan B. Munch, David O. Conover, Stephen R. Palumbi.

*Hopkins Marine Station, Stanford University; NOAA Southwest Fisheries Science Center; Stony Brook University; Hopkins Marine Station, Stanford University.*

Multi-generational selection experiments offer a powerful approach for directly observing how the genome responds to known selection pressures over time. We have returned to a seminal experiment that demonstrated substantial evolution in growth rate (resulting in a nearly two-fold difference in adult size) in response to size-selective fishing over just five generations in the Atlantic silverside. Based on 'in silico' capture of genomic sequence, we compared allele frequencies at >800K SNPs distributed across ~80% of the exome in large vs. small selected lines. We identified strong differentiation at 1118 SNPs, including nearly fixed differences in 17 genes. High divergence occurs in bone morphogenic proteins and macrophage stimulating factors, previously linked to growth. However, selected genes maintain high overall levels of diversity, indicating that selection has primarily acted as 'soft' sweeps on old alleles. Because natural variation in size selection across latitudes has driven strong clinal adaptation in growth rate in the Atlantic silverside, we compare the sweep signatures from the experiment with genome scans of wild populations. This integrated analysis of responses to natural and artificial selection on the same complex trait offers parallel insights into the genomic basis for life history adaptation evolved over various time scales.

# The genetic basis of parallel evolution in an introduced species (52994)

Billie Gould, **John Stinchcombe**.

*University of Toronto.*

The goal of identifying the genes or even nucleotides underlying quantitative and adaptive traits has been characterized as the 'QTN programme' and has recently come under severe criticism. Part of the reason for this criticism is that much of the QTN programme has asserted that finding the genes and nucleotides for adaptive and quantitative traits is a fundamental goal, without explaining why it is such a hallowed goal. Here we outline motivations for the QTN programme that offer general insight, regardless of whether QTNs are of large or small effect, and that aid our understanding of the mechanistic dynamics of adaptive evolution, illustrating with examples from research we have done on introduced populations of the model plant, Arabidopsis thaliana. We combine outlier scans (XTX), molecular population genetic tests of selection, and the rich list of flowering time candidate genes to test for regions of the genome involved in parallel adaptation. Our results indicate that parallel adaptation in
A Clinal Polymorphism in Insulin Signaling Has Major Effects on Drosophila Life History (52690)

Esra Durmaz, Subhash Rajpurohit, Nicolas Betancourt, Paul S. Schmidt, Thomas Flatt.

Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland;
Department of Biology, University of Pennsylvania, Philadelphia, USA; Department of
Biology, University of Pennsylvania, Philadelphia, USA; Department of Biology, University
of Pennsylvania, Philadelphia, USA; Department of Ecology and Evolution, University of
Lausanne, Lausanne, Switzerland.

Several life history traits in Drosophila melanogaster exhibit strong clinal differentiation across latitude, for example along the North American east coast, from Florida to Maine. Similarly, at the genetic level, we have recently identified major genome-wide patterns of clinal differentiation, likely shaped by spatially varying (clinal) selection. Interestingly, we find particularly strong clinal variation in numerous genes involved in insulin/insulin-like growth factor signaling (IIS), a pathway known from laboratory mutant and transgenic studies to physiologically regulate fitness traits. However, whether natural allelic variants in genes of this pathway affect life history remains poorly understood. Here, we have examined life history effects of a naturally occurring, clinally varying candidate haplotype in dFOXO, a downstream effector of IIS. We used recombinant inbred (DGRP) lines to establish two sets of synthetic recombinant populations either fixed for the northern or southern allelic state. Our results show, for the first time, that a clinally varying, naturally occurring polymorphism in dFOXO has major pleiotropic effects upon starvation resistance and body size, two important fitness traits known to be strongly clinal.

Parasitoid adaptation to hosts with symbiont-conferred resistance (51859)

Alice Dennis, Christoph Vorburger.

ETH Zurich & EAWAG; ETH Zurich & EAWAG.

In host-parasitoid systems, variation in host defenses create a set of environments to which
parasitoids must adapt in order to reproduce. For the parasitoid wasp Lysiphlebus fabarum
this also includes evolving responses to the diverse, heterogeneous, microbiome of their aphid
host. To investigate the genomic basis of varied wasp infectivity, we have experimentally
evolved wild-caught wasps on three different aphid hosts: two lines possessing different
defensive strains of the symbiont Hamiltonella defensa, and one un-infected line. In just 10
generations, this has produced wasp lines with different, and non -reciprocal, infective
abilities, presumably by selection of pre-existing genetic variation from the wild populations. Using RNAseq, we have identified differentially expressed genes associated with each selected wasp infectivity-phenotype. We are now using these to examine the functional genomic basis of the infective abilities of the evolved lines and to screen natural populations of L. fabarum for the relevant molecular variation over time and space.

# Endosymbiotic bacteria protect aphids against natural enemies in a natural wet meadow habitat (51915)

Jan Hrcek, H. Charles J. Godfray.

*Department of Zoology, University of Oxford.*

Endosymbiont mediated protection is a widespread phenomenon with potential to allow rapid adaptation by horizontal transfer. Pea aphids harbour endosymbiotic bacteria which protect them against parasitoids and fungal pathogens. We ask whether the spatial and temporal heterogeneity in natural enemy pressure and the specificity of the endosymbiont mediated protection allow the protection previously demonstrated in laboratory experiments to affect aphid mortality rates under natural conditions.

We deployed sentinel populations of aphids with and without protective endosymbionts for ten days at five naturally managed meadows in a 15km circle around Oxford, UK, three times during 2014 season. Sentinel aphids were attacked by a rich community of parasitoids and fungal pathogens of up to six species per site. Endosymbionts protected aphids in the field in accordance with predictions from laboratory experiments. However, the complexity of multiple concurrent antagonistic interactions and high specificity of the bacterial protection led to increased aphid survival only in some of the spatio-temporal replicates.

This work shows that the phenotypic effects of endosymbionts identified through a decade of laboratory research on aphids are ecologically relevant in a natural habitat and demonstrates the importance of field experiments in revealing the outcome of attack by a community of natural enemies.

# All aboard! Tracking host-parasite historical associations in the Canary Islands. (51930)

Fátima Jorge, Ana Perera, Robert Poulin, Vicente Roca, Miguel A. Carretero.

CIBIO Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Vairão, P; Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, Porto, Portugal; Department of Zoology, University of Otago, Dunedin, New Zealand;
Host parasite associations are the outcome of historical events and current ecological conditions. Several cophylogenetic events can shape such intimate interactions, i.e. cospeciation, host switching and missing the boat. Given their long term isolation and structure, the Canary Islands provide an ideal environment for studying the origin and evolution of host-parasite associations. Did parasites follow the colonisation of islands by their host or did they undergo other events such as host switches? In our study, we reconstructed the origins of the current associations between parasitic nematodes and all their reptile hosts from the Canary Islands. Parasite phylogeny was inferred from molecular data with maximum Likelihood and Bayesian methods. The most likely evolutionary history of these associations was reconstructed on the basis of our estimated parasite phylogeny and on published host phylogenies. Results suggest at least three different colonisations events in the Canary archipelago and some level of evolutionary congruence with their hosts. One lineage probably originated from a host switch between skinks and lacertids but evolving separately since. Overall, while island colonisations by parasites are initially determined by stochastic events (whether or not they get in the boat), how they evolve subsequently may be mainly dependent on parasite adaptation (specificity).

Population size shape reciprocal adaptations in the experimental host-parasite
coevolution (51967)

**Andrei Papkou**, Rebecca Schalkowski, Mike-Christoph Barg, Ines Braker, Hinrich Schulenburg.

Genomic regions involved in host-parasite interaction are subjected to intense selection. This
may lead to either rapid allele fixations or continuous frequency oscillations. However, the
resulting allele dynamics is not solely determined by selection, but additionally depends on
genetic variation and random drift. Population size (N) is, therefore, an important
characteristic in this respect as it influences genetic diversity and selection-drift interplay.
Surprisingly, little is known about the role of N in coevolution, despite the fact that N varies
considerably across host and parasite species and changes frequently due to their interaction
and external factors.

To examine empirically how N influences antagonistic adaptation, we initiated experimental coevolution between the nematode Caenorhabditis elegans and its pathogen Bacillus thuringiensis in large, small and periodically changing populations. The effect of N was already evident after 23 host generations. In particular, we found that changes in host fecundity and parasite virulence varied depending on population size. Moreover, a time-shift experiment revealed the patterns of negative frequency-dependent selection in the large populations, but not in the small populations. Next, we used population genomics and infection transcriptomics approaches to identify candidate regions, and to assess the contribution of different evolutionary forces to the underlying genetic changes.
# Testing for genetic differentiation along altitudinal gradients in ticks (Ixodes ricinus) (52121)

**Mélissa Lemoine**, Barbara Tschirren.

*Institute for Evolutionary Biology and Environmental Studies.*

Due to its broad host range and its wide distribution, the European sheep tick (Ixodes ricinus) has for a long time been considered as a generalist vector. Recent genetic studies suggest however that locally adapted populations exist, specialising on different host species. Since eggs and larvae of Ixodes ticks are highly vulnerable to temperature and humidity, both abiotic and biotic factors may potentially play a role in shaping spatial genetic differentiation of tick populations. Therefore I. ricinus is an excellent study system for examining the contributions of isolation-by-ecology vs isolation-by-distance to spatial genetic divergence. Using larvae collected from voles in 12 sites among altitudinal gradients in Swiss Alps, we estimated the contributions of temperature and humidity as well as geographical and host genetic distances to genetic divergence of tick populations using neutral markers. This study helps to understand whether the current rapid colonisation of new environments by I. ricinus is linked with the colonisation of these environments by its hosts or with its intrinsic evolutionary potential.

# Eco-evolutionary dynamics in coevolving host-virus systems (52276)

Jens Frickel, **Lutz Becks**.

*Community Dynamics Group, Dept. Evolutionary Ecology, Max Planck Institute for Evolutionary Biology.*

Eco-evolutionary dynamics - the interplay of ecology and evolution on the same time scale - have been shown to influence population and community as well as evolutionary dynamics in many complex ways. However, coevolution in the framework of eco-evolutionary theory has not been addressed directly. Using experiments with an algal host and its virus, we show here for the first time eco-evolutionary feedback dynamics in antagonistic coevolving populations. Specifically, we found that the continuous reciprocal adaption of resistance and infectivity in host and virus drove the ecological dynamics of the system leading ultimately to a shift from consumer-resource cycles to stable population sizes. The coevolutionary dynamics were initially driven by arms race dynamics with consecutive selective sweeps, but shifted towards fluctuating selection as a result of an evolutionary constraint in the virus and the evolution of a trade-off between host resistance range and growth rate. Importantly, our results show that the role of selection and demography changes continuously over time as a result of the eco-evolutionary feedback. Consequently, the entanglement of ecology and evolution has
# Host age structure as a source of heterogeneity in host-parasite interactions (52545)

**Frida Ben-Ami.**

*Tel Aviv University.*

Understanding the interplay between the epidemiology and ecology of host and parasite populations is of utmost importance in light of recent epidemics and growing resistance towards drug treatments. Particularly in microparasites, where ecological dynamics such as within-host competition can strongly influence evolutionary change, they must be studied conjointly to understand disease evolution. While genetic heterogeneity has received considerable attention in both theoretical and experimental studies of host-parasite interactions, there is very little data on how host age, an intrinsic and highly dynamic property of the host population as well as a key epidemiological factor, impacts ecological and evolutionary dynamics of host and parasite populations. Using the Daphnia magna-Pasteuria ramosa system, I will present results from several recent experiments that demonstrate the complex interplay between host demography and the ecology of host and parasite populations. In particular, I will show that host age at exposure can affect parasite infectivity, virulence and reproduction as well as within-host competition and parasite diversity. I will also make a case for incorporating age-dependent epidemiological parameters into stage-structured theory and virulence modeling. Ultimately, elucidating the underlying dynamics will improve our understanding of disease ecology and virulence evolution.

# Testing inclusive fitness theory in a lower termite (51905)

**Judith Korb**, Katharina Hoffmann.

*University of Freiburg; University of Osnabrueck.*

Inclusive fitness theory predicts that interactions between relatedness and ecological costs and benefits determine altruism, however empirical studies in social insects commonly concentrate on relatedness. Less studied termites offer a promising test case to study the interaction between relatedness and altruism because different termite castes vary in degree of altruism: Soldiers are always sterile and can only gain indirect fitness. In contrast, workers of wood-dwelling lower termites are immature instars that are less altruistic and have the full capability to become reproductives. By manipulating local resource availability and the opportunity to reproduce in colonies of varying degree of relatedness, we show that the importance of relatedness differed for different castes and that nepotism always was context
dependent. Sterile soldiers adjusted their behaviour more strongly to relatedness than the less altruistic workers which can themselves reproduce. For all castes the adjustment was a phenotypic plastic response and it only occurred when helping increased the chance of relatives to become reproductives. Furthermore, strong local resource competition negated the effect of relatedness. Our study it one of very few social insect studies that demonstrates how ecological factors interact with relatedness in flexibly shaping social interactions and cooperation.

# An evolutionarily significant unicellular strategy in response to starvation in Dictyostelium social amoebae (51912)

**Clement Nizak**, Minus van Baalen, Darja Dubravcic.

CNRS - ESPCI ParisTech; CNRS - Ecole Normale Supérieure.

The social amoeba Dictyostelium discoideum is widely studied for its multicellular development as a response to starvation. Aggregates of up to 10^6 cells form fruiting bodies containing (i) dormant spores (~80%) that can persist for months in the absence of nutrients, and (ii) dead stalk cells (~20%) that promote the dispersion of the spores towards nutrient-rich areas.

Using a new quantitative approach based on time-lapse fluorescence microscopy and a low ratio of reporting cells, we have quantified the fraction of non-aggregating cells. In realistic starvation conditions, up to 15% of cells do not aggregate. Non-aggregating cells have an advantage over cells in aggregates since they resume growth earlier upon arrival of new nutrients, but have a shorter lifespan under prolonged starvation. We find that phenotypic heterogeneities linked to cell nutritional state and genetic factors bias the representation of cells in the aggregating vs. non-aggregating fractions. In addition, interactions between clones in mixtures of non-isogenic cells affect the partitioning of each clone into both fractions. We further build a numerical model to test the evolutionary significance of the non-aggregating cell fraction. The partitioning of cells into aggregating and non-aggregating fractions is optimal in fluctuating environments with an unpredictable duration of starvation periods.

# Cheating on the edge: spatial self-organization promotes cooperation in expanding bacterial colonies (52077)

**Alexandre Jousset**, Anna Hille, Stefan Scheu, Katrin Meyer.

Utrecht University; Georg-August University Göttingen.

Understanding the mechanisms underlying the evolution and stability of cooperative behaviors in microorganisms is one of the most exciting topics of microbial evolutionary biology. Many unicellular microorganisms engage in complex social behaviors in fighting
against enemies, scavenging for nutrients or forming complex structures in a joint effort. However, social behaviors are predicted to be unstable as defectors can readily live on the costs of their faithful neighbors, potentially disrupting cooperation. Here we show that expanding colonies show self-organization patterns that maintain cooperation. We follow the growth of Pseudomonas fluorescens colonies on a solid medium containing albumin as sole carbon source. Prior to uptake, albumin must be broken down by extracellular proteases, which function as public good. Using a combination of individual-based models and microscopy, we show that in expanding communities defectors first accumulate on the border of the colony, but their growth is restricted by low diffusion of public goods. As cooperators expand they engulf defectors thereby confining them to the center of the colony. Therefore, resource exploitation at the edge of expanding microbial colonies stabilizes cooperation in a spatially explicit context.

## Long Life, Promiscuity and the Origin of Cooperation in Birds (52360)

**Philip Downing.**

*Department of Zoology, University of Oxford.*

Long life is a common feature of cooperative societies in taxa as diverse as mammals and ants. However, it is not clear whether it is a cause or a consequence of cooperation. Theory predicts that the likelihood of cooperation evolving is higher in long-lived species because it ensures a long reproductive lifespan and therefore high direct fitness benefits. However, the effect of long life on cooperation also depends on whether individuals gain indirect fitness while helping, which is determined by female promiscuity: high promiscuity lowers indirect fitness benefits making the direct fitness gained from long life vital for cooperation to evolve. We tested these predictions comparatively by reconstructing ancestral states of breeding system and survival across birds and investigating the interaction between promiscuity and life span. As predicted by theory, we found that long life facilitates the evolution cooperation and that species with low indirect fitness are exceptionally long-lived, driving the difference in lifespan between cooperative and non-cooperative breeders. These results clarify the importance of life-history traits in the evolution of cooperative breeding. Furthermore, they suggest that promiscuous species can make the evolutionary transition to cooperation because long life compensates for the reduction in indirect fitness.

## Diversity in parent-offspring communication in birds: shifting between signals and cues (52636)

**Shana Caro, Ashleigh Griffin, Camilla Hinde, Stuart West.**

*University of Oxford, United Kingdom; Wageningen University, The Netherlands.*
Evolutionary theory has helped us understand communication in the natural world as a cooperative behaviour relying on the alignment of interests of both signaller and receiver. There is, however, a lack of empirical consensus for basic theoretical predictions even in one of the best studied systems: offspring begging their parents for food. Existing theory predicts both that offspring should display honest signals of need and that offspring should display honest signals of quality; these contrasting predictions have both received empirical support. We present the results of a meta-analysis, which resolve the current lack of synthesis by showing that parents integrate signals of need or quality differently depending on brood reduction strategy and environmental conditions. As food availability increases, parents in brood-reducing species allocate food more by begging intensity, but less by signals of quality like gape coloration and size cues. Offspring signalling strategies also shift with parental response strategies: the smallest offspring beg the most intensely only when partial brood starvation is unlikely. A separate, within-species, in-depth analysis on great tits found the same flexible response within a population. These empirical results demonstrate the need to account for ecology and dynamic strategy sets in signalling models.

# Developing social evolution theory into a set of tools for analyzing microbial data (52960)

**jeff smith.**

*Washington University in St Louis.*

Social evolution theory is a valuable guide for empirical research, but in many studies of microbial cooperation it is often only used as a verbal heuristic. Here I test the usefulness of different theoretical approaches in social evolution as tools for analyzing experimental data. I re-analyze published microbial data sets that share a common experimental design and identify the pros and cons of different approaches in terms of data visualization, ease of application, statistical power, theoretical interpretation, and generalization across systems. The regression-based approach of the Price equation that underlies many kin selection and multilevel selection models is often a poor choice for the large, nonlinear fitness effect common in microbial systems. Some measures of fitness are better than others. The functional form of frequency dependence is potentially very informative, but at present there is almost no theory with which to interpret it. These findings show that there is still a substantial need to formulate social evolution mathematics in a way that makes theory a useful guide for data collection and analysis.

# Fitness costs in spatially structured environments (51856)

**Florence Débarre.**

*wissenschaftskolleg zu berlin.*
The clustering of individuals that results from limited dispersal is a double-edged sword: while it allows for local interactions to be mostly among related individuals, it also results in increased local competition. In this talk, I will show that, because they mitigate local competition, fitness costs such as reduced fecundity or reduced survival are less costly in spatially structured environments than in non spatial settings. I will first present a simple demographic example to illustrate how spatial structure weakens selection against fitness costs. Then, I will illustrate the importance of disentangling the evolution of a trait from the evolution of potential associated costs. I will use an example taken from a recent study investigating the effect of spatial structure on the evolution of host defense -- a social trait, since fighting against parasites indirectly protects your neighbors. In this example indeed, the differences between spatial and non-spatial selection gradients are entirely due to differences in the fitness costs, thereby undermining interpretations of the results made in terms of the trait only. This illustrates the need to consider fitness costs as proper traits in both theoretical and empirical studies, and of not neglecting the effect of ecological feedbacks on evolution.

# Functional trade-offs and phenotypic diversity in cellular migration (53350)

## Thierry Emonet.

### Yale University.

Bacteria perform chemotaxis in a wide variety of environmental tasks, from scavenging nutrients to infecting host tissues. As such, it would seem unlikely that one type of chemotactic behavior would be equally suited to all tasks. Indeed, some species have many chemotaxis systems and switch between them. Others have one, but behavioral diversity is still observed in clonal wildtype cells. What are the trade-offs that bacteria face in performing chemotaxis in different environments? Can population diversity be tailored to resolve these trade-offs? I will discuss our recent theoretical and experimental efforts to uncover the functional role of phenotypic heterogeneity in cellular migration and understand how biological systems may resolve functional trade-offs.

# Bacterial Genomic Diversity in Light of Environmental Selection (53365)

## Martin Polz.

### Massachusetts Institute of Technology.

Many bacterial and archaeal lineages have a history of extensive gene acquisition and loss, evident as large genome content differences even among otherwise closely related isolates. Explaining the co-existence of the resultant vast genotypic diversity in light of selection remains one of the biggest challenges in microbial biology. Using marine vibrios as a model, we show that in spite of such high gene turnover, genotypic clusters representing ecologically
cohesive populations can be identified. These populations display many hallmarks of animal
and plant populations, including speciation, social interactions and ecological tradeoffs.
Population genomics shows that interactions among genotypes, e.g., via public good
production and cheating, and with predators, e.g., via variation of surface antigens, lead to
gene content variation among closely related genotypes. This provides a functional
explanation how biological interactions may select for coexisting high genomic diversity.

Is HIV short-sighted? Insights from a multistrain nested model (51615)

Katrina Lythgoe, Lorenzo Pellis, Christophe Fraser.

Imperial College London; University of Warwick.

An important component of pathogen evolution at the population level is evolution within hosts. Unless evolution within hosts is very slow compared to the duration of infection, the composition of pathogen genotypes within a host is likely to change during the course of an infection, thus altering the composition of genotypes available for transmission as infection progresses. We develop a nested modelling approach that allows us to follow the evolution of pathogens at the epidemiological level by explicitly considering within-host evolutionary dynamics of multiple competing strains and the timing of transmission. We use the framework to investigate the impact of short-sighted within-host evolution on the evolution of virulence of HIV, and find that the topology of within-host adaptive landscape determines how virulence evolves at the epidemiological level. If viral replication rates increase significantly during the course of infection, the viral population will evolve a high level of virulence even though this will reduce the transmission potential of the virus. However, if replication rates increase more modestly, as data suggests, our model predicts that HIV virulence will be only marginally higher than the level which maximizes the transmission potential of the virus.

Spatial constrains on public good production during biofilm development
(51658)

Theresa Hölscher, Benjamin Bartels, Ramses Gallegos-Monterrosa, Akos T Kovacs.

Friedrich Schiller University Jena, Terrestrial Biofilms Group.

Biofilms are structurally complex bacterial communities, where the cells are enclosed in an
extracellular matrix that mediates the attachment of cells to each other or to surfaces. While
the biofilm matrix benefits the population, i.e. protection, attachment to a substratum or
surface spreading, its production is costly for the individuals. Mutant strains of the Gram-
positive bacterium, Bacillus subtilis lacking matrix production have a higher fitness under
well mixed planktonic conditions. However, matrix producers have an advantage when
cultivated in spatially structured environment.

Two laboratory biofilm models of B. subtilis, surface colony biofilm and air liquid interface pellicle, are examined to understand how matrix producer cooperators gain advantage in a community. Strains lacking matrix production are excluded from a newly built pellicle, a developmental mechanism that selects for matrix producer cooperators. During colony development, spatial pattern formation facilitates cooperation in B. subtilis biofilms. The density of cells at the onset of biofilm growth affects pattern formation during biofilm growth. At low initial cell densities co-cultured strains strongly segregates in space, while at high initial cell densities they do not. EPS-producing cells have a competitive advantage over non-cooperative mutants at high assortment, while EPS-deficient cells have an advantage in mixed populations.

Session 2 THU MAX 415 25

## Migrating together: how Bacillus subtilis uses division of labor to colonize surfaces. (52089)

Jordi van Gestel, Hera Vlamakis, Roberto Kolter.

University of Groningen; Harvard University.

Multicellular organization results from the interactions between cells. From cell-cell interactions collective properties can emerge that enable cells to face challenges that they separately cannot. One particularly important challenge for micro-organisms is migration. In this study, we show how migration depends on the division of labor between two cell types, which appear during Bacillus subtilis colony expansion. Cell collectives organize themselves into bundles that form filamentous loops at the colony edge. These loops exert a novel mechanism of migration by pushing themselves away from the colony. The formation of filamentous bundles depended critically on the synergistic interaction of two distinct cell types: surfactin-producing and matrix-producing cells. We propose that surfactin-producing cells reduce the friction between cells and their substrate, which allows matrix-producing cells to form bundles and migrate towards uncolonized regions of the plate where nutrients have yet to be depleted. Our study illustrates how simple organization of cells can yield a strong ecological advantage. This and similar types of ecological advantages are key for the numerous evolutionary transitions towards primitive and complex multicellular life.

Session 2 THU MAX 415 25

## Experimental evolution of increased efficiency through serial propagation in emulsion (52948)

Iraes Rabbers, Frank Bruggeman, Herwig Bachmann, Bas Teusink.

VU University Amsterdam, dept. Systems Bioinformatics.
From an evolutionary perspective it is advantageous for single cells to grow fast -to outcompete competitors- and for microbial populations to use substrate efficiently -to make the most offspring-. Microbial cells are thought to be metabolically efficient when growing slow and inefficient when growing fast, giving rise to the concept "Tragedy of the commons". There is experimental evidence for this yield/rate tradeoff in i.a. yeast, however these experiments employed culturing methods where the selection pressure is on growth rate (batch) or substrate affinity (chemostat) due to resource competition. A novel method has recently been introduced that compartmentalizes individual cells in a water-in-oil emulsion, thereby privatizing the resources and allowing for yield selection upon serial propagation. In this project we applied this method to E. coli wildtype for ~450 generations, leading to selection of mutants with increased cell number, exhibiting increased final optical density, total protein content and biomass. This yield increase appears to result from more efficient substrate usage, mainly the full depletion of pyruvate in contrast with the ancestral strain. Characterization of these strains is ongoing, and should reveal the genetic basis for the high yield phenotype and in addition allow more insight into the existence of a yield/rate tradeoff in E. coli.

# Inference of past historical events using ABC and MCMC methods on population genetics data sets (52127)

## Frederic Austerlitz.

### Laboratoire EcoAnthropologie et Ethnobiologie.

New computer-intensive estimation techniques such as Approximate Bayesian Computation (ABC) and Monte Carlo Markov chains (MCMC) allows inferring unknown parts of the history of species from contemporary population genetics data. I will illustrate these possibilities with several examples. First, I will talk about a set of human populations from Western Central Africa. Using ABC, we could infer the history of splitting and admixture between these different groups. We could also identify sex-specific demographic processes. The second example that I will mention is the harbour porpoise (Phocoena phocoena) population from the Black Sea. Using again ABC techniques, we showed that this population underwent a strong expansion around 5000 years ago, probably as a result of the reconnection of the Black Sea with the Mediterranean Sea, but that it underwent also a drastic decline around 50 years ago. Finally I will talk about a study on worldwide human populations, in which by applying MCMC methods on a large set of populations with different lifestyles (farmers, herder and hunter-gatherers), we were able to show that these lifestyles strongly impacted the expansion patterns of these populations. These examples illustrate well how ABC and MCMC methods allow inferring precious information on the history of populations.

# Unravelling the evolutionary history of the mosquito disease vector Aedes aegypti; lineage diversification and successful worldwide colonisation (52150)
**Kelly Bennett.**

*University of Manchester.*

The natural boundaries of populations are limited by their ability to disperse and competitively utilise novel habitats. What governs the success of colonising populations? The dengue disease vector Aedes aegypti has been particularly successful in expanding its geographic range from ancestral Africa. The dengue mosquito is also one of few mosquitoes which have acquired the ability to breed in domestic habitats and associate with man. Studying the colonisation process of this mosquito could provide insight into the evolution of domesticity and factors contributing to the successful spread of disease vectors.

Previous studies based on microsatellite and SNP data suggest that domesticated populations outside of Africa represent a distinct genetic group different from populations found within Africa. On the other hand, mitochondrial studies find two genetic groups outside of Africa which may correspond to subspecies (associated with domestic and non-domestic habitats) or African geography (East and West Africa).

Findings from the present study suggest that divergent lineages within A.aegypti may have arisen through allopatric speciation during the Plio-Pleistocene. Divergent genetic lineages have undergone admixture associated with historical habitat change or human movement. I provide evidence that genetically heterogeneous populations of A.aegypti within Africa have contributed to the colonisation of new geographic areas outside of Africa.

Session 2 THU GEN B 35

**Running faster or jumping further? Analysis of adaptive walks in various classes of fitness landscapes. (52502)**

**Barbora Trubenova, Tiago Paixao.**

*IST Austria.*

In evolutionary biology it is often assumed that mutations are sufficiently rare and selection sufficiently strong to consider a population to be monomorphic at most of the time, 'jumping' between different genotypes. Analysis of adaptive walks in this regime have frequently resorted to simplifying assumptions about the fitness landscapes. In particular, they typically assume that selection coefficients are drawn from extreme-value distributions and that mutational neighbourhoods are not correlated.

This Strong Selection Weak Mutation (SSWM) model is closely analogous to (1+1) Evolutionary Algorithm (EA), used in computer science. The analysis of the performance of this algorithm have lead to tools that allow its analysis in classes of fitness functions, without disregarding their correlation structure. Making use of tools from computer science, we analyse several properties of adaptive walks in various classes of fitness landscapes, including average jump size, speed of adaptation and time until they reach the optimum.
# The molecular mechanisms and reversibility of fisheries-induced evolution (52542)

Silva Uusi-Heikkilä, Tiina Sävilammi, Spiros Papakostas, Robert Arlinghaus, Craig Primmer.

*University of Turku; Leibniz-Institute of Freshwater Ecology and Inland Fisheries.*

Large shifts in phenotypic traits have been observed in exploited fish populations, which have not always fully recovered despite fishing has been ceased. Fisheries-induced evolution (FIE) can explain these potentially slowly reversible changes. However, detecting signals of FIE and its reversibility has proven difficult. We study the molecular mechanisms of FIE by sequencing the transcriptome of experimental fish (wild-origin zebrafish, Danio rerio) that have been harvested size selectively for five generations and then maintained under no-selection for six generations. We studied 1) what are the molecular mechanisms underlying FIE, 2) does intensive size-selective harvesting affect gene expression variation, and 3) whether the genetic changes caused by size-selective harvesting are reversible. Our results show that five generations of size selection induced substantial changes in gene expression. In addition to expression evolution, we found signals of sequence evolution: a large number of SNPs were candidates for being subject to selection. We further show that size-selective harvesting generally reduced gene expression variation. Harvest-induced changes in gene expression were eroded after cessation of size-selective harvesting but there was no clear sign of recovery at the sequence level. Similarly, gene expression variation did not rebound back to the initial levels.

# Density dependence determines the role of extrinsic mortality in shaping life history traits (52318)

Maciej J. Dańko, Oskar Burger, Jan Kozłowski.

Max Planck Institute for Demographic Research; University of Kent School of Anthropology and Conservation (Canterbury, UK) ; Institute of Environmental Sciences, Jagiellonian University (Kraków, PL).

There is still debate about the role of extrinsic mortality in shaping life histories, especially the evolution of ageing. We show that the effect of extrinsic mortality depends on ecological conditions, particularly the effect of density dependence on population growth rate. We propose a novel method that combines the idea of the Evolutionary Unbeatable Strategy (EUS) with a projection matrix and resource allocation model. We consider three general classes of density dependence: acting on (i) mortality, (ii) fecundity or (iii) on resource acquisition rate. We extend previous research by allowing density effects in each of these cases to be constant or to vary with age or body mass. For each case we demonstrate the effects of density-independent extrinsic mortality on resource allocation strategies. We find that the effect of extrinsic mortality depends not only on the model of density dependence, but also on the strength of change in density dependent effects with age or size. For each scenario we compare EUS strategies with strategies resulting from maximization of more standard
measures of fitness (like r or R), and identify cases where neither of the standard measures provide correct predictions about the optimal allocation strategy.

# Sex-specific evolution of learning performance, locomotion, reproduction and lifespan in an outcrossing nematode (51828)

**Martyna Zwoinska**, Martin Lind, Maria Cortazar, Mark Ramsden, Alexei Maklakov.

*Evolutionary Biology Centre, Uppsala University.*

Evolution of learning performance is constrained by trade-offs with life-history traits. Since male and female life-histories often diverge the costs and benefits of learning can differ between the sexes but intersexual genetic correlation will constrain the sexes from reaching their optimal trait values. We selected Caenorhabditis remanei nematode females for increased and decreased olfactory learning and measured learning performance, locomotory activity, reproductive performance and lifespan in virgin and mated males and females. While both sexes responded to selection, males performed better than females in two different learning assays. Downward-selected males showed higher locomotory activity and longer virgin lifespan yet sired fewer progeny than upward-selected males supporting the trade-off between learning and lifespan, and showing that increased reproduction and learning performance do not depend on increased activity. Strikingly, while we observed no effect of selection on female reproduction, virgin downward-selected females lived shorter than upward-selected females. Opposing effects of olfactory learning selection on lifespan evolution in the two sexes led to the reversal of sexual dimorphism in virgin lifespan in downward-selected lines, where virgin males outlived virgin females. Our results show that sex-specific genetic architecture results in the evolution of sexually dimorphic life-histories despite intersexual genetic correlation for learning performance.

# A comprehensive phylogenetic study of mammalian embryology and skeletogenesis reveals the altricial life history of the placental ancestor, modularity and a brain-bone development link (51627)

**Marcelo Sánchez-Villagra**, Ingmar Werneburg, Michel Laurin, Daisuke Koyabu.

*University of Zurich; University of Zurich; Muséum National d'Histoire Naturelle, Paris; University Museum, University of Tokyo.*

We present the first comprehensive and phylogenetic study of mammalian organogenesis and skeletogenesis in all major clades. Our study is based on Museum specimens and non-invasive imaging and synthesis of embryological data. We coded the relative timing of discrete events, e.g. onset of ossification of all bones of the skeleton and major events in organogenesis and life history. Using heterochrony analyses, we reconstructed the ancestral