The Genetic Variability and Demographic History of a Population of the Even-Year Broodline Pink Salmon Oncorhynchus gorbuscha (Walbaum, 1792) (Bakhura River, Sakhalin Island) Inferred from the Polymorphism of Two Mitochondrial Genes

To estimate the genetic variability of the pink salmon Oncorhynchus gorbuscha (Walbaum, 1792) of even-year broodlines from the Bakhura River, Sakhalin Island, the polymorphism of nucleotide sequences of the ND2 and Cytb genes (mtDNA) with a total length of 1809 bp has been analyzed. In 211 pink salmon specimens from three samples of different years, a total of 44 haplotypes at 39 polymorphic sites have been identified. The neutrality tests indicate a high probability of purifying selection in the studied genes. The analysis of mismatch distribution, the neutrality tests, and the Bayesian skyline data support the expansion model for the even-year broodline pink salmon population. The study of the haplotype divergence history based on Bayesian chronogram shows that the divergence within the main phylogroups occurred in the intervals of 40 400–54 300 and 4800–25 000 years ago.