title: [The variation in chum salmon Oncorhynchus keta (Walbaum) mitochondrial DNA and its connection with the paleogeographic events in the Northwest Pacific].
abstract: The results of examining mtDNA variation in populations of chum salmon Oncorhynchus keta from the rivers of the basins of the seas of Japan and Okhotsk and in the chum salmon seasonal races of the Amur River are presented. A significant level of polymorphism between the majority of the populations studied was detected. The groups of chum salmon from the Japan and Okhotsk Seas displayed the most pronounced differences. Analysis of genetic variation demonstrated that periodic paleontologic and climatic changes in the past of this region were the most probable factor that caused the divergence of these populations. The advances and retreats of glaciers and the accompanying regressions and transgressions of the ocean level caused isolation of chum salmon in the refugia belonging hypothetically to the paleo-Suifun and paleo-Amur regions. These population groups diverged presumably 350-450 thousand years ago. Differences between the seasonal races of the Amur chum salmon are insignificant, and their emergence dates back to the period of the last Wisconsin glaciation. Probably, the main isolation factor now is the genetically determined time of spawning.
authors.forename: N E
authors.initials: NE
authors.lastname: Poliakova
authors.forename: A V
authors.initials: AV
authors.lastname: Semina
authors.forename: V A
authors.initials: VA
authors.lastname: Brykov
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics*; D005618:Fresh Water; D014644:Genetic Variation; D009792:Oceans and Seas; D017685:Oncorhynchus keta / Q000235:genetics*; D010802:Phylogeny; D012800:Siberia
chemical_list: D004272:DNA, Mitochondrial