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SNP signatures of selection on standing genetic variation and their association with adaptive phenotypes along gradients of ecological speciation in lake whitefish species pairs ( Coregonus spp.)
Author(s) -
RENAUT SÉBASTIEN,
NOLTE ARNE W.,
ROGERS SEAN M.,
DEROME NICOLAS,
BERNATCHEZ LOUIS
Publication year - 2011
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/j.1365-294x.2010.04952.x
Subject(s) - biology , coregonus clupeaformis , coregonus , genetics , genetic architecture , evolutionary biology , ecological speciation , sympatric speciation , genetic variation , quantitative trait locus , gene , gene flow , fishery , fish <actinopterygii>
As populations adapt to novel environments, divergent selection will promote heterogeneous genomic differentiation via reductions in gene flow for loci underlying adaptive traits. Using a data set of over 100 SNP markers, genome scans were performed to investigate the effect of natural selection maintaining differentiation in five lakes harbouring sympatric pairs of normal and dwarf lake whitefish ( Coregonus clupeaformis ). A variable proportion of SNPs (between 0% and 12%) was identified as outliers, which corroborated the predicted intensity of competitive interactions unique to each lake. Moreover, strong reduction in heterozygosity was typically observed for outlier loci in dwarf but not in normal whitefish, indicating that directional selection has been acting on standing genetic variation more intensively in dwarf whitefish. SNP associations in backcross hybrid progeny identified 16 genes exhibiting genotype–phenotype associations for four adaptive traits (growth, swimming activity, gill rakers and condition factor). However, neither simple relationship between elevated levels of genetic differentiation with adaptive phenotype nor conspicuous genetic signatures for parallelism at outlier loci were detected, which underscores the importance of independent evolution among lakes. The integration of phenotypic, transcriptomic and functional genomic information identified two candidate genes (sodium potassium ATPase and triosephosphate isomerase) involved in the recent ecological divergence of lake whitefish. Finally, the identification of several markers under divergent selection suggests that many genes, in an environment‐specific manner, are recruited by selection and ultimately contributed to the repeated ecological speciation of a dwarf phenotype.