Dataset Information

RAD-Seq Reveals Patterns of Additive Polygenic Variation Caused by Spatially-Varying Selection in the American Eel (Anguilla rostrata).

ABSTRACT: The American Eel (Anguilla rostrata) has an exceptional life cycle characterized by panmictic reproduction at the species scale, random dispersal, and selection in a highly heterogeneous habitat extending from subtropical to subarctic latitudes. The genetic consequences of spatially-varying selection in this species have been investigated for decades, revealing subtle clines in allele frequency at a few loci that contrast with complete panmixia on the vast majority of the genome. Because reproduction homogenizes allele frequencies every generation, sampling size, and genomic coverage are critical to reach sufficient power to detect selected loci in this context. Here, we used a total of 710 individuals from 12 sites and 12,098 high-quality single nucleotide polymorphisms to re-evaluate the extent to which local selection affects the spatial distribution of genetic diversity in this species. We used environmental association methods to identify markers under spatially-varying selection, which indicated that selection affects ?1.5% of the genome. We then evaluated the extent to which candidate markers collectively vary with environmental factors using additive polygenic scores. We found significant correlations between polygenic scores and latitude, longitude and temperature which are consistent with polygenic selection acting against maladapted genotypes in different habitats occupied by eels throughout their range of distribution. Gene functions associated with outlier markers were significantly enriched for the insulin signaling pathway, indicating that the trade-offs inherent to occupying such a large distribution range involve the regulation of metabolism. Overall, this study highlights the potential of the additive polygenic scores approach in detecting selective effects in a complex environment.

SUBMITTER: Babin C

PROVIDER: S-EPMC5714190 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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RAD-Seq Reveals Patterns of Additive Polygenic Variation Caused by Spatially-Varying Selection in the American Eel (Anguilla rostrata).

Babin Charles C Gagnaire Pierre-Alexandre PA Pavey Scott A SA Bernatchez Louis L

Genome biology and evolution 20171101 11

The American Eel (Anguilla rostrata) has an exceptional life cycle characterized by panmictic reproduction at the species scale, random dispersal, and selection in a highly heterogeneous habitat extending from subtropical to subarctic latitudes. The genetic consequences of spatially-varying selection in this species have been investigated for decades, revealing subtle clines in allele frequency at a few loci that contrast with complete panmixia on the vast majority of the genome. Because reprodu ...[more]

PMID: 29136139

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Project description:BackgroundAmerican eel (Anguilla rostrata) is one of the few species for which panmixia has been demonstrated at the scale of the entire species. As such, the development of long term local adaptation is impossible. However, both plasticity and spatially varying selection have been invoked in explaining how American eel may cope with an unusual broad scope of environmental conditions. Here, we address this question through transcriptomic analyses and genomic reaction norms of eels from two geographic origins reared in controlled environments.ResultsThe null hypothesis of no difference in gene expression between eels from the two origins was rejected. Many unique transcripts and two out of seven gene clusters showed significant difference in expression, both at time of capture and after three months of common rearing. Differences in expression were observed at numerous genes representing many functional groups when comparing eels from a same origin reared under different salinity conditions. Plastic response to different rearing conditions varied among gene clusters with three clusters showing significant origin-environment interactions translating into differential genomic norms of reaction. Most genes and functional categories showing differences between origins were previously shown to be differentially expressed in a study comparing transcription profiles between adult European eels acclimated to different salinities.ConclusionsThese results emphasize that while plasticity in expression may be important, there is also a role for local genetic (and/or epigenetic) differences in explaining differences in gene expression between eels from different geographic origins. Such differences match those reported in genetically distinct populations in other fishes, both in terms of the proportion of genes that are differentially expressed and the diversity of biological functions involved. We thus propose that genetic differences between glass eels of different origins caused by spatially varying selection due to local environmental conditions translates into transcriptomic differences (including different genomic norms of reaction) which may in turn explain part of the phenotypic variance observed between different habitats colonized by eels.

Dataset Information

RAD-Seq Reveals Patterns of Additive Polygenic Variation Caused by Spatially-Varying Selection in the American Eel (Anguilla rostrata).

Publications

RAD-Seq Reveals Patterns of Additive Polygenic Variation Caused by Spatially-Varying Selection in the American Eel (Anguilla rostrata).

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