Genomic Basis of Domestication Selection in Coho Salmon

Characterizing the genomic basis of domestication selection helps understand the mechanism of adaptive evolution and the extent to which selection causes divergence between domesticated and wild animals. The aims of this study were to construct a dense linkage map for coho salmon (Oncorhynchus kisutch) and to identify genomic regions that have responded to domestication selection by integrating QTL mapping and genome scans. Specifically, we mapped quantitative trait loci underlying growth-related traits and determined whether these loci played a role in adaptive evolution by comparing the domesticated line to its unselected source hatchery population, and the wild population related to the hatchery.

A dense linkage map was constructed with 8681 Restriction site associated DNA (RAD) markers, comprising 30 linkage groups. Strong differentiation and locus-specific loss of genetic diversity on some linkage groups were observed in the domesticated population; some of these genomic regions overlapped with the detected QTLs, indicating that these regions have played a role in adaptive phenotypic differentiation driven by domestication selection. As the traits targeted in this study are related to fitness in the wild, such information help understand the mechanisms of adaptive evolution in this species, and assist effective conservation and management of wild and hatchery populations.