bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clonal diversity driven by parasitism in a freshwater snail
Authors: Dagan Y. , Liljeroos K. , Jokela J. , Ben‐Ami F. 
Published: October 2013

AbstractOne explanation for the widespread abundance of sexual reproduction is the advantage that genetically diverse sexual lineages have under strong pressure from virulent coevolving parasites. Such parasites are believed to track common asexual host genotypes, resulting in negative frequency‐dependent selection that counterbalances the population growth‐rate advantage of asexuals in comparison with sexuals. In the face of genetically diverse asexual lineages, this advantage of sexual reproduction might be eroded, and instead sexual populations would be replaced by diverse assemblages of clonal lineages. We investigated whether parasite‐mediated selection promotes clonal diversity in 22 natural populations of the freshwater snail Melanoides tuberculata. We found that infection prevalence explains the observed variation in the clonal diversity of M. tuberculata populations, whereas no such relationship was found between infection prevalence and male frequency. Clonal diversity and male frequency were independent of snail population density. Incorporating ecological factors such as presence/absence of fish, habitat geography and habitat type did not improve the predictive power of regression models. Approximately 11% of the clonal snail genotypes were shared among 2–4 populations, creating a web of 17 interconnected populations. Taken together, our study suggests that parasite‐mediated selection coupled with host dispersal ecology promotes clonal diversity. This, in return, may erode the advantage of sexual reproduction in M. tuberculata populations.
The role of founder effects on the evolution of reproductive isolation
Authors: Matute D. R. 
Published: October 2013

AbstractSeveral theories argue that large changes in allele frequencies through genetic drift after a small founding population becomes allopatrically isolated can lead to significant changes in reproductive isolation and thus trigger the origin of new species. For this reason, founder speciation has been proposed as a potent force in the generation of new species. Nonetheless, the relative importance of such ‘founder effects’ remains largely untested. In this report, I used experimental evolution to create one thousand replicates that underwent an extreme bottleneck and to study whether founder effects can lead to an increase in reproductive isolation inDrosophila yakuba. Even though the most common outcome of inbreeding is extinction, founder effects can lead to increased premating reproductive isolation in a very small proportion of cases. Changes in reproductive isolation after a founding population bottleneck are similar to changes in other phenotypic traits, in which inbreeding might displace the mean phenotypic value and substantially increase the phenotypic variance. This increase in phenotypic variance does not confer an increase in the response to selection for reproductive isolation in artificial selection experiments, indicating that the increased phenotypic variance is not caused by increases in additive genetic variance. These results also demonstrate that, similar to morphological and life‐history traits, behavioural traits can be affected by inbreeding and genetic drift.
The relative contribution of drift and selection to transcriptional divergence among Babine Lake tributary populations of juvenile rainbow trout
Authors: Wellband K. W. , Heath D. D. 
Published: October 2013

AbstractFine‐scale population structure has been widely described for salmonid populations using neutral genetic markers, but whether that structure reflects adaptive differences among the populations remains of interest to evolutionary biologists and conservation managers alike. The use of transcriptomics to quantify population differences in genetically controlled functional gene expression traits holds promise for investigating this divergence associated with possible local adaptation. We use custom microarrays to characterize population divergence in transcription at functionally relevant (metabolic and immune function) genes among tributary populations of rainbow trout from Babine Lake, BC and compare it to neutral divergence estimated from microsatellite markers. Transcriptional divergence (PST) was determined at resting state and in response to metabolic and immune challenges, two major sources of mortality and thus selective forces on juvenile salmonids. Results indicate that the majority of selected genes [56 genes (65%), 64 genes (63%) and 38 genes (78%) under control, temperature and immune challenges respectively] show transcriptional divergence (PST > FST) that is consistent with the action of divergent selection. Patterns of pairwise PST among populations are inconsistent with evolution by drift. In general, it appears that the magnitude and pattern of population divergence in transcription reflect the action of natural selection and identify selection on transcription as a mechanism for local adaptation. These results reinforce the need to conserve salmonids on a tributary basis and provide insight into genetic mechanisms that facilitate local adaptation.
Epistasis and maternal effects in experimental adaptation to chronic nutritional stress inDrosophila
Authors: Vijendravarma R. K. , Kawecki T. J. 
Published: October 2013

AbstractBased on ecological and metabolic arguments, some authors predict that adaptation to novel, harsh environments should involve alleles showing negative (diminishing return) epistasis and/or that it should be mediated in part by evolution of maternal effects. Although the first prediction has been supported in microbes, there has been little experimental support for either prediction in multicellular eukaryotes. Here we use a line‐cross design to study the genetic architecture of adaptation to chronic larval malnutrition in a population ofDrosophila melanogasterthat evolved on an extremely nutrient‐poor larval food for 84 generations. We assayed three fitness‐related traits (developmental rate, adult female weight and egg‐to‐adult viability) under the malnutrition conditions in 14 crosses between this selected population and a nonadapted control population originally derived from the same base population. All traits showed a pattern of negative epistasis between alleles improving performance under malnutrition. Furthermore, evolutionary changes in maternal traits accounted for half of the 68% increase in viability and for the whole of 8% reduction in adult female body weight in the selected population (relative to unselected controls). These results thus support both of the above predictions and point to the importance of nonadditive effects in adaptive microevolution.
Lack of parallel genetic patterns underlying the repeated ecological divergence of beach and stream‐spawning kokanee salmon
Authors: Frazer K. K. , Russello M. A. 
Published: October 2013

AbstractRecent progress in methods for detecting adaptive population divergence in situ shows promise for elucidating the conditions under which selection acts to generate intraspecific diversity. Rapid ecological diversification is common in fishes; however, the role of phenotypic plasticity and adaptation to local environments is poorly understood. It is now possible to investigate genetic patterns to make inferences regarding phenotypic traits under selection and possible mechanisms underlying ecotype divergence, particularly where similar novel phenotypes have arisen in multiple independent populations. Here, we employed a bottom‐up approach to test for signatures of directional selection associated with divergence of beach‐ and stream‐spawning kokanee, the obligate freshwater form of sockeye salmon (Oncorhynchus nerka). Beach‐ and stream‐spawners co‐exist in many post‐glacial lakes and exhibit distinct reproductive behaviours, life‐history traits and spawning habitat preferences. Replicate ecotype pairs across five lakes in British Columbia, Canada were genotyped at 57 expressed sequence tag‐linked and anonymous microsatellite loci identified in a previous genome scan. Fifteen loci exhibited signatures of directional selection (high FST outliers), four of which were identified in multiple lakes. However, the lack of parallel genetic patterns across all lakes may be a result of: 1) an inability to detect loci truly under selection; 2) alternative genetic pathways underlying ecotype divergence in this system; and/or 3) phenotypic plasticity playing a formative role in driving kokanee spawning habitat differences. Gene annotations for detected outliers suggest pathogen resistance and energy metabolism as potential mechanisms contributing to the divergence of beach‐ and stream‐spawning kokanee, but further study is required.
Genetic architecture of sensory exploitation: QTL mapping of female and male receiver traits in an acoustic moth
Authors: Alem S. , Streiff R. , Courtois B. , Zenboudji S. , Limousin D. , Greenfield M. D. 
Published: October 2013

AbstractThe evolution of extravagant sexual traits by sensory exploitation occurs if males incidentally evolve features that stimulate females owing to a pre‐existing environmental response that arose in the context of natural selection. The sensory exploitation process is thus expected to leave a specific genetic imprint, a pleiotropic control of the original environmental response and the novel sexual response in females. However, females may be subsequently selected to improve their discrimination of environmental and sexual stimuli. Accordingly, responses may have diverged and the original genetic architecture may have been modified. These possibilities may be considered by studying the genetic architecture of responses to male signals and to the environmental stimuli that were purportedly ‘exploited’ by those signals. However, no previous study has addressed the genetic control of sensory exploitation. We investigated this question in an acoustic pyralid moth, Achroia grisella, in which a male ultrasonic song attracts females and perception of ultrasound likely arose in the context of detecting predatory bats. We examined the genetic architecture of female response to bat echolocation signals and to male song via a cartographic study of quantitative trait loci (QTL) influencing these receiver traits. We found several QTL for both traits, but none of them were colocalized on the same chromosomes. These results indicate that – to the extent to which male A. grisella song originated by the process of sensory exploitation – some modification of the female responses occurred since the origin of the male signal.
How to distinguish altruism from spite (and why we should bother)
Authors: Krupp D. B. 
Published: October 2013

AbstractSocial behaviour is often described as altruistic, spiteful, selfish or mutually beneficial. These terms are appealing, but it has not always been clear how they are defined and what purpose they serve. Here, I show that the distinctions among them arise from the ways in which fitness is partitioned: none can be drawn when the fitness consequences of an action are wholly aggregated, but they manifest clearly when the consequences are partitioned into primary and secondary (neighbourhood) effects. I argue that the primary interaction is the principal source of adaptive design, because (i) it is this interaction that determines the fit of an adaptation and (ii) it is the actor and primary recipients whom an adaptation foremost affects. The categories of social action are thus instrumental to any account of evolved function.
The social evolution of dispersal with public goods cooperation
Authors: Taylor T. B. , Rodrigues A. M. M. , Gardner A. , Buckling A. 
Published: October 2013

AbstractSelection can favour the evolution of individually costly dispersal if this alleviates competition between relatives. However, conditions that favour altruistic dispersal also mediate selection for other social behaviours, such as public goods cooperation, which in turn is likely to mediate dispersal evolution. Here, we investigate – both experimentally (using bacteria) and theoretically – how social habitat heterogeneity (i.e. the distribution of public goods cooperators and cheats) affects the evolution of dispersal. In addition to recovering the well‐known theoretical result that the optimal level of dispersal increases with genetic relatedness of patch mates, we find both mathematically and experimentally that dispersal is always favoured when average patch occupancy is low, but when average patch occupancy is high, the presence of public goods cheats greatly alters selection for dispersal. Specifically, when public goods cheats are localized to the home patch, higher dispersal rates are favoured, but when cheats are present throughout available patches, lower dispersal rates are favoured. These results highlight the importance of other social traits in driving dispersal evolution.
Contribution of the X chromosome to a marked reduction in lifespan in interspecies female hybrids of Drosophila simulans and D. mauritiana
Authors: Dickman C. T. D. , Moehring A. J. 
Published: October 2013

AbstractWhen two species come into contact and interbreed, the production of unfit hybrids can limit or prevent gene flow between the populations, thus maintaining each species’ separate identity. The genetic basis of this hybrid dysfunction has recently begun to be elucidated, particularly for hybrid sterility and inviability. Although these dysfunctions can certainly act as a barrier to gene flow, other post‐zygotic barriers may also play an important role in isolating species from one another. This study examines the genetic basis of the more subtle mechanism of species isolation via a marked reduction in lifespan of interspecies hybrid offspring. We found that females with homozygous X chromosomes in an otherwise interspecies hybrid background displayed a significant reduction in lifespan; this effect is not due to genetic background and appears to arise from complex genetic interactions. Separately, there is an additional severe reduction in lifespan for attached‐X females when they have mated with males of either parental species, which is partly due to interspecific genetic interactions, but primarily due to a female's increased sensitivity to mating when bearing a Y chromosome or the attached‐X chromosome construct.
Corticosterone regulates multiple colour traits in Lacerta [Zootoca] vivipara males
Authors: San‐Jose L. M. , Fitze P. S. 
Published: October 2013

AbstractOrnamental colours usually evolve as honest signals of quality, which is supported by the fact that they frequently depend on individual condition. It has generally been suggested that some, but not all types of ornamental colours are condition dependent, indicating that different evolutionary mechanisms underlie the evolution of multiple types of ornamental colours even when these are exhibited by the same species. Stress hormones, which negatively affect condition, have been shown to affect colour traits based on different pigments and structures, suggesting that they mediate condition dependence of multiple ornament types both among and within individuals. However, studies investigating effects of stress hormones on different ornament types within individuals are lacking, and thus, evidence for this hypothesis is scant. Here, we investigated whether corticosterone mediates condition dependence of multiple ornaments by manipulating corticosterone levels and body condition (via food availability) using a two‐factorial design and by assessing their effect on multiple colour traits in male common lizards. Corticosterone negatively affected ventral melanin‐ and carotenoid‐based coloration, whereas food availability did not affect coloration, despite its significant effect on body condition. The corticosterone effect on melanin‐ and carotenoid‐based coloration demonstrates the condition dependence of both ornaments. Moreover, corticosterone affected ventral coloration and had no effect on the nonsexually selected dorsal coloration, showing specific effects of corticosterone on ornamental ventral colours. This suggests that corticosterone simultaneously mediates condition dependence of multiple colour traits and that it therefore accounts for covariation among them, which may influence their evolution via correlational selection.
Changing clinical practice: management of paediatric community‐acquired pneumonia
Authors: Elemraid Mohamed A. , Rushton Stephen P. , Thomas Matthew F. , Spencer David A. , Eastham Katherine M. , Gennery Andrew R. , Clark Julia E. ,   North East of England Paediatric Respiratory Infection Study Group
Published: October 2013

AbstractRationale and aimTo compare clinical features and management of paediatric community‐acquired pneumonia (PCAP) following the publication of UK pneumonia guidelines in 2002 with data from a similar survey at the same hospitals in 2001–2002 (pre‐guidelines).MethodsA prospective survey of 11 hospitals in Northern England was undertaken during 2008–2009. Clinical and laboratory data were recorded on children aged ≤16 years who presented with clinical and radiological features of pneumonia.Results542 children were included. There was a reduction in all investigations performed (P < 0.001) except C‐reactive protein (P = 0.448) between surveys. These included full blood count (76% to 61%); blood culture (70% to 53%) and testing of respiratory secretions for viruses (24% to 12%) and bacteria (18% to 8%). Compared to pre‐guidelines, there was a reduction in the use of intravenous antibiotics as a proportion of the total prescribed from 47% to 36% (P < 0.001) and a change in the route of antibiotic administration with increasing preference for oral alone (16% pre‐compared to 50% post‐guidelines, P < 0.001).ConclusionApart from the acute phase reactants that should not be measured routinely, these changes are in line with the guideline recommendations. Improvements in antibiotic use are possible and have implications for future antimicrobial stewardship programmes. Further work using cost‐effectiveness analysis may also demonstrate a financial benefit to health services from adoption of guidelines.
First report of viral nervous necrosis‐induced mass mortality in hatchery‐reared larvae of clownfish, Amphiprion sebae Bleeker
Authors: Binesh C P , Renuka K , Malaichami N , Greeshma C 
Published: October 2013

AbstractFrequent mortality was observed in the larval rearing facility of marine clownfish, Amphiprion sebae Bleeker. Mortality resulted in 80% loss of larval stock. Moribund larvae showed clinical signs typical of viral nervous necrosis, such as uncoordinated, corkscrew‐like swimming behaviour, hypersensitivity to stimuli, darkening of body and assembly into large groups, similar to bunches of grapes. The aetiology of the disease was confirmed by gross observation of clinical signs, histopathology and molecular diagnosis. Histological studies revealed severe vacuolation in the brain and in the bipolar and ganglion layers of the eye. Molecular diagnosis by reverse transcription–polymerase chain reaction (RT‐PCR) specific to piscine nodavirus yielded a positive result. The partial nucleotide sequences of the PCR‐amplified fragment were 97–98% similar to other betanodavirus isolates reported globally and more closely aligned with red‐spotted grouper nervous necrosis virus (RGNNV). This is the first report of susceptibility of clownfish, A. sebae, to betanodavirus and the presence of the RGNNV in India.
In vitro passages impact on virulence of Saprolegnia parasitica to Atlantic salmon, Salmo salar L. parr
Authors: Songe M M , Thoen E , Evensen Ø , Skaar I 
Published: October 2013

AbstractThe effect of serial in vitro subculturing on three pathogenic strains of Saprolegnia parasitica was investigated. The isolates were passed through Atlantic salmon, Salmo salar L. parr, and then re‐isolated as single spore colonies. All strains caused infection. The isolate obtained from diseased fish served as a virulent reference culture and was designated ‘AP’ (‘activated through passage’). Successive subculturing was made by obtaining an inoculum from AP to produce the 2nd subculture and then passaged to the 3rd subculture (from the 2nd), until the 15th passage was obtained. Spores used to produce storage cultures were collected at passages 5, 10 and 15. The different passages of each strain were used to artificially infect Atlantic salmon parr. Morphological characterization of growth patterns was performed to observe differences occurring due to serial in vitro subculturing. Two of the strains declined in virulence after 15 successive in vitro subcultures, whereas one did not. This study is the first to investigate attenuation of virulence in Saprolegnia and whether or not isolates of S. parasitica should be passed through the fish host prior to challenge experiments. It reveals that some strains degenerate more rapidly than others when subjected to successive in vitro subculturing on glucose–yeast extract.
Development of chitosan conjugated DNA vaccine against nodavirus in Macrobrachium rosenbergii (De Man, 1879)
Authors: Ramya V L , Sharma R , Gireesh‐Babu P , Patchala S R , Rather A , Nandanpawar P C , Eswaran S 
Published: October 2013

AbstractThe protective efficacy of a DNA construct containing extra small virus antisense (XSVAS) gene of nodavirus encapsulated with chitosan nanoparticles (NPs) was investigated in giant freshwater prawn Macrobrachium rosenbergii (De Man, 1879). The delivery was carried out using oral and immersion methods. A plasmid concentration of 100 ng μL−1 when conjugated with chitosan NPs was found to be more effective in increasing the survivability of the infected prawn. The particle mean size, zeta potential and loading efficiency percentage were 297 nm, 27 mV and 85%, respectively. The ability of the chitosan to form a complex with the plasmid was studied by agarose gel electrophoresis. The NPs were characterized by atomic force microscopy (AFM). Persistence study showed the presence of the DNA construct up to 30th day post‐treatment. The oral treatment was found to be better than the immersion treatment for delivery of the chitosan‐conjugated DNA construct. This is probably the first report on the delivery of nanoconjugated DNA construct in M. rosenbergii, against nodavirus.