bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eco‐evolutionary rescue promotes host–pathogen coexistence
Authors: DiRenzo Graziella V. , Zipkin Elise F. , Grant Evan H. Campbell , Royle J. Andrew , Longo Ana V. , Zamudio Kelly R. , Lips Karen R. 
Published: October 2018

AbstractEmerging infectious pathogens are responsible for some of the most severe host mass mortality events in wild populations. Yet, effective pathogen control strategies are notoriously difficult to identify, in part because quantifying and forecasting pathogen spread and disease dynamics is challenging. Following an outbreak, hosts must cope with the presence of the pathogen, leading to host–pathogen coexistence or extirpation. Despite decades of research, little is known about host–pathogen coexistence post‐outbreak when low host abundances and cryptic species make these interactions difficult to study. Using a novel disease‐structured N‐mixture model, we evaluate empirical support for three host–pathogen coexistence hypotheses (source–sink, eco‐evolutionary rescue, and spatial variation in pathogen transmission) in a Neotropical amphibian community decimated byBatrachochytrium dendrobatidis(Bd) in 2004. During 2010–2014, we surveyed amphibians in Parque Nacional G. D. Omar Torríjos Herrera, Coclé Province, El Copé, Panama. We found that the primary driver of host–pathogen coexistence was eco‐evolutionary rescue, as evidenced by similar amphibian survival and recruitment rates between infected and uninfected hosts. Average apparent monthly survival rates of uninfected and infected hosts were both close to 96%, and the expected number of uninfected and infected hosts recruited (via immigration/reproduction) was less than one host per disease state per 20‐m site. The secondary driver of host–pathogen coexistence was spatial variation in pathogen transmission as we found that transmission was highest in areas of low abundance but there was no support for the source–sink hypothesis. Our results indicate that changes in the host community (i.e., through genetic or species composition) can reduce the impacts of emerging infectious disease post‐outbreak. Our disease‐structured N‐mixture model represents a valuable advancement for conservation managers trying to understand underlying host–pathogen interactions and provides new opportunities to study disease dynamics in remnant host populations decimated by virulent pathogens.
Should I shoot or should I go? Simple rules for prey selection in multi‐species hunting systems
Authors: Chang Charlotte H. , Drohan Sarah E. 
Published: October 2018

AbstractAcross the tropics, unregulated hunting targeting many different species presents a major conservation challenge. Prioritizing resources for monitoring and enforcement is difficult when multiple prey species are exploited. However, identifying which prey species are subject to hunting pressure can be achieved with diet choice models. We evaluate hunter diet sets using data from Southwest China and compare two diet choice models: optimal foraging theory and a relatively new diet model originating from economic optimal stopping problems. The optimal stopping diet choice model required fewer field parameters than optimal foraging models and more accurately reflected hunter catch in Southwest China. The optimal stopping model also indicated that hunters should be less selective when they experience a larger opportunity cost for their time. Finally, we illustrate a new method to evaluate harvest impact from single sites with limited data using dietary thresholds. This technique could be used to evaluate whether or not the community of exploited wildlife has shifted in its trait distribution, providing a means to anticipate trait‐biased defaunation from minimal data.
Phenotypic correlation between queen and worker brood care supports the role of maternal care in the evolution of eusociality
Authors: Walsh Justin T. , Signorotti Lisa , Linksvayer Timothy A. , d'Ettorre Patrizia 
Published: October 2018

AbstractCooperative brood care by siblings, a defining feature of eusociality, is hypothesized to be evolutionarily derived from maternal care via shifts in the timing of the expression of genes underlying maternal care. If sibling and maternal care share a genetic basis, the two behaviors are expected to be genetically and phenotypically correlated. We tested this prediction in the black garden ant Lasius niger by quantifying the brood retrieval rate of queens and their first and later generation worker offspring. Brood retrieval rate of queens was positively phenotypically correlated with the brood retrieval rate of first generation but not with later generation workers. The difference between first and later generation workers could be due to the stronger similarity in care behavior provided by queens and first generation workers compared to later generations. Furthermore, we found that queen retrieval rate was positively correlated with colony productivity, suggesting that natural selection is acting on maternal care. Overall, our results support the idea of a shared genetic basis between maternal and sibling care as well as queen and worker traits more generally, which has implications for the role of intercaste correlations in the evolution of queen and worker traits and eusociality.
Mycorrhizal interactions do not influence plant–herbivore interactions in populations of Clarkia xantiana ssp. xantiana spanning from center to margin of the geographic range
Authors: Bolin Lana G. , Benning John W. , Moeller David A. 
Published: October 2018

AbstractMultispecies interactions can be important to the expression of phenotypes and in determining patterns of individual fitness in nature. Many plants engage in symbiosis with arbuscular mycorrhizal fungi (AMF), but the extent to which AMF modulate other species interactions remains poorly understood. We examined multispecies interactions among plants, AMF, and insect herbivores under drought stress using a greenhouse experiment and herbivore choice assays. The experiment included six populations of Clarkia xantiana (Onagraceae), which span a complex environmental gradient in the Southern Sierra Nevada of California. Clarkia xantiana's developing fruits are commonly attacked by grasshoppers at the end of the growing season, and the frequency of attack is more common in populations from the range center than range margin. We found that AMF negatively influenced all metrics of plant growth and reproduction across all populations, presumably because plants supplied carbon to AMF but did not benefit substantially from resources potentially supplied by the AMF. The fruits of plants infected with AMF did not differ from those without AMF in their resistance to grasshoppers. There was significant variation among populations in damage from herbivores but did not reflect the center‐to‐margin pattern of herbivory observed in the field. In sum, our results do not support the view that AMF interactions modulate plant–herbivore interactions in this system.
The impact of autotrophic versus heterotrophic nutritional pathways on colony health and wound recovery in corals
Authors: Burmester Elizabeth M. , Breef‐Pilz Adrienne , Lawrence Nicholas F. , Kaufman Les , Finnerty John R. , Rotjan Randi D. 
Published: October 2018

AbstractFor animals that harbor photosynthetic symbionts within their tissues, such as corals, the different relative contributions of autotrophy versus heterotrophy to organismal energetic requirements have direct impacts on fitness. This is especially true for facultatively symbiotic corals, where the balance between host‐caught and symbiont‐produced energy can be altered substantially to meet the variable demands of a shifting environment. In this study, we utilized a temperate coral–algal system (the northern star coral, Astrangia poculata, and its photosynthetic endosymbiont, Symbiodinium psygmophilum) to explore the impacts of nutritional sourcing on the host's health and ability to regenerate experimentally excised polyps. For fed and starved colonies, wound healing and total colony tissue cover were differentially impacted by heterotrophy versus autotrophy. There was an additive impact of positive nutritional and symbiotic states on a coral's ability to initiate healing, but a greater influence of symbiont state on the recovery of lost tissue at the lesion site and complete polyp regeneration. On the other hand, regardless of symbiont state, fed corals maintained a higher overall colony tissue cover, which also enabled more active host behavior (polyp extension) and endosymbiont behavior (photosynthetic ability of Symbiondinium). Overall, we determined that the impact of nutritional state and symbiotic state varied between biological functions, suggesting a diversity in energetic sourcing for each of these processes.
Trade‐off between reproductive and anti‐competitor abilities in an insect–parasitic nematode–bacteria symbiosis
Authors: Bertoloni Meli Sofia , Bashey Farrah 
Published: October 2018

AbstractMutualistic symbionts can provide diverse benefits to their hosts and often supply key trait variation for host adaptation. The bacterial symbionts of entomopathogenic nematodes play a crucial role in successful colonization of and reproduction in the insect host. Additionally, these symbionts can produce a diverse array of antimicrobial compounds to deter within‐host competitors. Natural isolates of the symbiont, Xenorhabdus bovienii, show considerable variation in their ability to target sympatric competitors via bacteriocins, which can inhibit the growth of sensitive Xenorhabdus strains. Both the bacteria and its nematode partner have been shown to benefit from bacteriocin production when within‐host competition with a sensitive competitor occurs. Despite this benefit, several isolates of Xenorhabdus do not inhibit sympatric strains. To understand how this variation in allelopathy could be maintained, we tested the hypothesis that inhibiting isolates face a reproductive cost in the absence of competition. We tested this hypothesis by examining the reproductive success of inhibiting and non‐inhibiting isolates coupled with their natural nematode host in a non‐competitive context. We found that nematodes carrying non‐inhibitors killed the insect host more rapidly and were more likely to successfully reproduce than nematodes carrying inhibitors. Lower reproductive success of inhibiting isolates was repeatable across nematode generations and across insect host species. However, no difference in insect mortality was observed between inhibiting and non‐inhibiting isolates when bacteria were injected into insects without their nematode partners. Our results indicate a trade‐off between the competitive and reproductive roles of symbionts, such that inhibiting isolates, which are better in the face of within‐host competition, pay a reproductive cost in the absence of competition. Furthermore, our results support the hypothesis that symbiont variation within populations can be maintained through context‐dependent fitness benefits conferred to their hosts. As such, our study offers novel insights into the selective forces maintaining variation within a single host–symbiont population and highlights the role of competition in mutualism evolution.
The Antarctic Circumpolar Current isolates and connects: Structured circumpolarity in the sea star Glabraster antarctica
Authors: Moore Jenna M. , Carvajal Jose I. , Rouse Greg W. , Wilson Nerida G. 
Published: October 2018

AbstractAimThe Antarctic Circumpolar Current (ACC) connects benthic populations by transporting larvae around the continent, but also isolates faunas north and south of the Antarctic Convergence. We test circumpolar panmixia and dispersal across the Antarctic Convergence barrier in the benthic sea star Glabraster antarctica.LocationThe Southern Ocean and south Atlantic Ocean, with comprehensive sampling including the Magellanic region, Scotia Arc, Antarctic Peninsula, Ross Sea, and East Antarctica.MethodsThe cytochrome c oxidase subunit I (COI) gene (n = 285) and the internal transcribed spacer region 2 (ITS2; n = 33) were sequenced. We calculated haplotype networks for each genetic marker and estimated population connectivity and the geographic distribution of genetic structure using ΦST for COI data.ResultsGlabraster antarctica is a single circum‐Antarctic species with instances of gene flow between distant locations. Despite the homogenizing potential of the ACC, population structure is high (ΦST = 0.5236), and some subpopulations are genetically isolated. Genetic breaks in the Magellanic region do not align with the Antarctic Convergence, in contrast with prior studies. Connectivity patterns in East Antarctic sites are not uniform, with some regional isolation and some surprising affinities to the distant Magellanic and Scotia Arc regions.Main conclusionsDespite gene flow over extraordinary distances, there is strong phylogeographic structuring and genetic barriers evident between geographically proximate regions (e.g., Shag Rocks and South Georgia). Circumpolar panmixia is rejected, although some subpopulations show a circumpolar distribution. Stepping‐stone dispersal occurs within the Scotia Arc but does not appear to facilitate connectivity across the Antarctic Convergence. The patterns of genetic connectivity in Antarctica are complex and should be considered in protected area planning for Antarctica.
The disproportionate importance of long‐unburned forests and woodlands for reptiles
Authors: Dixon Kelly M. , Cary Geoffrey J. , Worboys Graeme L. , Gibbons Philip 
Published: October 2018

AbstractOur understanding of the impacts of time since fire on reptiles remains limited, partly because there are relatively few locations where long‐term, spatially explicit fire histories are available. Such information is important given the large proportion of some landscapes that are managed with frequent prescribed fire to meet fuel management objectives. We conducted a space‐for‐time study across a landscape in southeastern Australia where the known fire history spanned 6 months to at least 96 years. Four methods were used to survey reptiles in 81 forest and woodland sites to investigate how time since fire (TSF), habitat, and environmental variables affect reptile richness, abundance, and composition. We used generalized linear models, generalized linear mixed‐effects models, PERMANOVA, and SIMPER to identify relationships between the reptile assemblage (richness, abundance, and composition, respectively) and TSF, habitat, and environmental variables. All three reptile metrics were associated with TSF. Reptile richness and abundance were significantly higher in sites >96 years postfire than younger fire ages (0.5–12 years). Reptile composition at long‐unburned sites was dissimilar to sites burned more recently but was similar between sites burned 0.5–2 and 6–12 years prior to sampling. Synthesis and applications. Long‐unburned forests and woodlands were disproportionately more important for reptile richness and abundance than areas burned 6 months to 12 years prior to sampling. This is important given that long‐unburned areas represent <8% of our study area. Our results therefore suggest that reptiles would benefit from protecting remaining long‐unburned areas from fire and transitioning a greater proportion of the study area to long‐unburned. However, some compositional differences between the long‐unburned sites and sites 0.5–12 years postfire indicate that maintaining a diversity in fire ages is important for conserving reptile diversity.
Chemistry of floral rewards: intra‐ and interspecific variability of nectar and pollen secondary metabolites across taxa
Authors: Palmer‐Young Evan C. , Farrell Iain W. , Adler Lynn S. , Milano Nelson J. , Egan Paul A. , Junker Robert R. , Irwin Rebecca E. , Stevenson Philip C. 
Published: October 2018

AbstractFloral chemistry mediates plant interactions with pollinators, pathogens, and herbivores, with major consequences for fitness of both plants and flower visitors. The outcome of such interactions often depends on compound dose and chemical context. However, chemical diversity and intraspecific variation of nectar and pollen secondary chemistry are known for very few species, precluding general statements about their composition. We analyzed methanol extracts of flowers, nectar, and pollen from 31 cultivated and wild plant species, including multiple sites and cultivars, by liquid‐chromatography–mass‐spectrometry. To depict the chemical niche of each tissue type, we analyzed differences in nectar and pollen chemical richness, absolute and proportional concentrations, and intraspecific variability. We hypothesized that pollen would have higher concentrations and more compounds than nectar, consistent with Optimal Defense Theory and pollen's importance as a male gamete. To investigate chemical correlations across and within tissues, which could reflect physiological constraints, we quantified chemical overlap between conspecific nectar and pollen, and phenotypic integration of individual compounds within tissue types. Nectar and pollen were chemically differentiated both across and within species. Of 102 compounds identified, most occurred in only one species. Machine‐learning algorithms assigned samples to the correct species and tissue type with 98.6% accuracy. Consistent with our hypothesis, pollen had 23.8‐ to 235‐fold higher secondary chemical concentrations and 63% higher chemical richness than nectar. The most common secondary compound classes were flavonoids, alkaloids, terpenoids, and phenolics (primarily phenylpropanoids including chlorogenic acid). The most common specific compound types were quercetin and kaempferol glycosides, known to mediate biotic and abiotic effects. Pollens were distinguished from nectar by high concentrations of hydroxycinnamoyl‐spermidine conjugates, which affect plant development, abiotic stress tolerance, and herbivore resistance. Although chemistry was qualitatively consistent within species and tissue types, concentrations varied across cultivars and sites, which could influence pollination, herbivory, and disease in wild and agricultural plants. Analyses of multivariate trait space showed greater overlap across sites and cultivars in nectar than pollen chemistry; this overlap reflected greater within‐site and within‐cultivar variability of nectar. Our analyses suggest different ecological roles of nectar and pollen mediated by chemical concentration, composition, and variability.
Disturbance differentially affects alpha and beta diversity of ants in tallgrass prairies
Authors: Kim Tania N. , Bartel Savannah , Wills Bill D. , Landis Douglas A. , Gratton Claudio 
Published: October 2018

AbstractBiodiversity conservation requires understanding how disturbance influences biodiversity patterns at multiple spatial scales. Because the total diversity of species within a given region (γ diversity) is influenced by both local diversity (α diversity) and dissimilarity in community composition (β diversity), understanding disturbance effects on both components of diversity is essential, especially if disturbance impacts α and β diversities differently. In this three‐year study, we examined how a disturbance (annual harvesting of grasslands) and environmental gradients in the proportion of sand locally, habitat size, and landscape diversity influenced the abundance and α and β diversities of ants within tallgrass prairie habitat in Wisconsin. We used a null‐model approach to examine how harvest and environmental factors influence β diversity. Following three years of treatments, we found that ant abundance was greater in harvested sites compared to control sites and ant abundance was positively correlated with soil sandiness. We also found that α diversity was lower in harvested sites compared to control sites and none of the measured environmental gradients influenced α diversity. The effects of harvest on α‐diversity patterns may have been mediated through the competitive interactions of the two dominant ant species (Formica montanaandLasius neoniger). In contrast, β diversity (after adjusting for random effects and changes to α diversity) was higher in harvest sites compared to control sites, and variability in community composition was largely driven by the occurrence of rare species. The proportion of sand in the local habitat and habitat size positively influenced β diversity suggesting that community dissimilarity was due in part to environmental filtering and the size of species pools. Because biomass harvest had contrasting effects on ant α and β diversities, trade‐offs in maintaining α vs. β diversity might need to be considered in land management and conservation efforts.
Low heterozygosity is associated with vector‐borne disease in crows
Authors: Townsend Andrea K. , Taff Conor C. , Wheeler Sarah S. , Weis Allison M. , Hinton Mitch G. , Jones Melissa L. , Logsdon Ryane M. , Reisen William K. , Freund David , Sehgal Ravinder N. M. , Saberi Mojan , Suh Young Ha , Hurd Jacqueline , Boyce Walter M. 
Published: October 2018

AbstractInfectious diseases can have devastating impacts on wildlife populations and are of particular concern for small, inbred populations. Identifying specific pathogens that are linked to morbidity and mortality in inbred individuals is a priority for the conservation of small populations, but opportunities to examine them in the wild are rare. Here, we examined the relationship between heterozygosity and infectious disease in American crows (Corvus brachyrhynchos), a species that engages in close inbreeding, focusing on three pathogens common in Davis, California, USA: West Nile virus (WNV), Plasmodium spp. (avian malaria), and Campylobacter jejuni. We found that low heterozygosity at a panel of 33 microsatellite loci was associated with two vector‐borne infectious diseases (WNV and avian malaria), but not with infection by the bacterial gut pathogen C. jejuni. Reasons for this association with vector‐borne pathogens are unclear, but might include behavioral factors and immunological differences associated with inbreeding. Overall, these data are consistent with the idea that inbred individuals may be more susceptible to both novel and endemic vector‐borne pathogens, underscoring the importance of protecting genetic diversity within populations and buffering small populations against infectious diseases.
Phylogenetic trait conservatism predicts patterns of plant‐soil feedback
Authors: Senior John K. , Potts Brad M. , O'Reilly‐Wapstra Julianne M. , Bissett Andrew , Wooliver Rachel C. , Bailey Joseph K. , Glen Morag , Schweitzer Jennifer A. 
Published: October 2018

AbstractPlant‐soil feedbacks (PSFs) are important drivers of plant community structure and diversity, with species varying in the way they both condition soils and respond to them. While plant phylogenetic relationships alone can predict this variation in some instances, trait conservatism across phylogenies may provide more reliable predictions. Using integrated common garden and glasshouse inoculation experiments including 13 Eucalyptus species across two subgenera, we specifically investigated soil microbial conditioning and root chemical traits as underlying drivers of phylogenetic differences in PSF. We found that eucalypt species responded variably to soils conditioned by closely related species, depending on their phylogenetic lineage, which was further related to root terpene concentrations and the presence/absence of specific fungal taxa in conditioned soils. Overall, these findings show that trait conservatism in root chemical traits and the subsequent conditioning of soil microbial communities can explain whether or not plants show phylogenetic patterns in PSF.