Relative Genetic Diversity Estimates among Four Pacific Salmonids

The genetic diversity within a species is a reflection of its evolutionary past and ongoing mutation, drift, and adaptation. Species that occupy a diverse range of habitats and that have adapted for generations under selective pressures will carry a genetic imprint of that adaptation within specific functional genes. Alternatively, genetic diversity may be reduced owing to historical bottlenecks and genetic drift. In this study, genetic diversity was estimated in four species of Pacific salmon (rainbow trout, steelhead [anadromous rainbow trout] Oncorhynchus mykiss, Chinook salmon O. tshawytscha, coho salmon O. kisutch, and sockeye salmon, kokanee [lacustrine sockeye salmon] O. nerka) using 563-608 kilo-base pairs of DNA sequence data from 32 individuals per species. Individual samples were chosen to represent the major lineages of each species across their natural ranges. The results show the highest genetic diversity estimates for rainbow trout and the lowest for sockeye salmon. Statistically significant differences were observed between the species with the highest genetic diversity (rainbow trout) and the three remaining species. Loci with the highest genetic diversity within each species are listed as potentially being influenced by balancing selection.