Journal article · Ahead of Print article
Northern European Salmo trutta (L.) populations are genetically divergent across geographical regions and environmental gradients
National Institute of Aquatic Resources, Technical University of Denmark1
Section for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark2
University of Gothenburg3
Vattenfall4
Aarhus University5
University of Agder6
Norwegian University of Life Sciences7
The salmonid fish Brown trout is iconic as a model for the application of conservation genetics to understand and manage local interspecific variation. However, there is still scant information about relationships between local and large‐scale population structure, and to what extent geographic and environmental variables are associated with barriers to gene flow.
We used information from 3782 mapped SNPs developed for the present study and conducted outlier tests and gene‐environment association (GEA) analyses in order to examine drivers of population structure. Analyses comprised >2600 fish from 72 riverine populations spanning a central part of the species’ distribution in northern Europe.
We report hitherto unidentified genetic breaks in population structure, indicating strong barriers to gene flow. GEA loci were widely spread across genomic regions and showed correlations with climatic, abiotic and geographical parameters. In some cases, individual loci showed consistent GEA across the geographical regions Britain, Europe and Scandinavia.
In other cases, correlations were observed only within a subset of regions, suggesting that locus specific variation was associated with local processes. A paired population sampling design allowed us to evaluate sampling effects on detection of outlier loci and GEA. Two widely applied methods for outlier detection (pcadapt, bayescan) showed low overlap in loci identified as statistical outliers across subsets of data.
Two GEA analytical approaches (LFMM, RDA) showed good correspondence concerning loci associated with specific variables, but LFMM identified five times more statistically significant associations than RDA. Our results emphasize the importance of carefully considering the statistical methods applied for the hypotheses being tested in outlier analysis.
Sampling design may have lower impact on results if the objective is to identify GEA loci and their population distribution. Our study provides new insights into trout populations and results have direct management implications in serving as a tool for identification of conservation units.
Language: | English |
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Publisher: | John Wiley and Sons Inc. |
Year: | 2020 |
Pages: | 400-416 |
ISSN: | 17524571 and 17524563 |
Types: | Journal article and Ahead of Print article |
DOI: | 10.1111/eva.12877 |
ORCIDs: | Bekkevold, Dorte , 0000-0001-5372-4828 , 0000-0002-2963-1928 and Eg Nielsen, Einar |
ASCERTAINMENT BIAS BROWN TROUT CLIMATE-CHANGE CONSERVATION Evolution GENOME SCANS LOCAL ADAPTATION QH359-425 R-PACKAGE SELECTION STRUCTURED POPULATIONS TEMPORAL-CHANGES brown trout genotype-environment association genotype‐environment association local adaptation outlier test salmonid