Our study also suggests that, both shared polymorphism among lineages, resulting from standing genetic variation or introgression, and chromosomal rearrangements may contribute to local adaptation in the presence of high gene flow. Genotype-environment associations revealed molecular signatures of local adaptation to environmental conditions prevailing at spawning sites. Within the NWA lineage, we detected a polymorphic chromosomal rearrangement leading to the occurrence of three haplogroups. Within each lineage, our analyses provided evidence for large N e and high gene flow among spawning sites. We reconstructed the history of divergence among three glacial lineages and showed that they likely diverged from 3.8 to 1.8 MyA and experienced secondary contacts.
Then, we used a large dataset of genome-wide single nucleotide polymorphisms (25,904 filtered SNPs) genotyped in 1,310 individuals collected from 31 spawning sites in the northwest Atlantic. We first assembled a 490 Mbp draft genome of M. In this study, we examined how demographic history, shared ancestral polymorphism, and gene flow among glacial lineages contribute to local adaptation to sea conditions in a marine fish, the capelin ( Mallotus villosus). However, our understanding of evolutionary mechanisms impending or favoring local adaptation in the presence of gene flow is still limited to a restricted number of study systems. Furthermore, structural variation as chromosomal rearrangements may facilitate adaptation despite high gene flow. Gene flow has tremendous importance on local adaptation, by influencing the fate of de novo mutations, maintaining standing genetic variation, and driving adaptive introgression.
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