Abstract
Clinal variation across replicated environmental gradients can reveal evidence of local adaptation, providing insight into the demographic and evolutionary processes that shape intraspecific diversity. Using 1773 genome-wide single nucleotide polymorphisms we evaluated latitudinal variation in allele frequency for 134 populations of North American and European Atlantic salmon (Salmo salar). We detected 84 (4.74%) and 195 (11%) loci showing clinal patterns in North America and Europe, respectively, with 12 clinal loci in common between continents. Clinal single nucleotide polymorphisms were evenly distributed across the salmon genome and logistic regression revealed significant associations with latitude and seasonal temperatures, particularly average spring temperature in both continents. Loci displaying parallel clines were associated with several metabolic and immune functions, suggesting a potential basis for climate-associated adaptive differentiation. These climate-based clines collectively suggest evidence of large-scale environmental associated differences on either side of the North Atlantic. Our results support patterns of parallel evolution on both sides of the North Atlantic, with evidence of both similar and divergent underlying genetic architecture. The identification of climate-associated genomic clines illuminates the role of selection and demographic processes on intraspecific diversity in this species and provides a context in which to evaluate the impacts of climate change.
Highlights
The analysis of geographically based genomic clines can illuminate the causes of population differentiation and reveal the interaction between natural selection and dispersal
We aim to test whether divergent or parallel evolution is occurring in the Atlantic Ocean by first comparing which loci show clinal patterns in North America and Europe, and investigating how the spatial structure of clinal loci varies with latitude, temperature and geographic distances
We report genomic clines in allele frequency associated with climate in both North American and European Atlantic salmon populations, suggesting parallel climate-associated evolution occurring in similar North Atlantic coastal habitats as a result of adaptive diversity or historical demographic processes
Summary
The analysis of geographically based genomic clines can illuminate the causes of population differentiation and reveal the interaction between natural selection and dispersal. Clinal variation has frequently been linked to biotic and abiotic factors, notably environmental gradients (e.g. temperature [1]; salinity [2,3,4]), which can impose spatially differential selective pressures. Regional differences in selective pressure may, be strong enough to overcome gene flow or drift among geographically distinct populations. Clines in Drosophila melanogaster alcohol dehydrogenase (Adh) have been revealed across different continents both historically [5,6] and as a response to climate change [7]. Because clines can form and vary in response to environmental selection, their location and intensity may shift with climate change. The identification of climateassociated genomic clines can illuminate the role of evolutionary processes on intraspecific diversity and provide a context against which to evaluate climate change impacts
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
