Phylogenetic analysis of Pacific salmon (genus Oncorhynchus) using nuclear and mitochondrial DNA sequences

Recent phylogenetic analyses of Pacific salmon of genus Oncorhynchus based on sequences from mitochondrial DNA and one nuclear growth hormone intron supported two subgroups:one with chinook (O. tshawytscha) and coho (O. kisutch) salmon and the other with pink (O. gorbuscha), sockeye (O. nerka), and chum (O. keta) salmon. In the latter group, a sister relationship was indicated between pink and chum salmon. Previous studies based on morphological and allozyme data had suggested a closer relationship between pink and sockeye salmon. In this paper we present a combined analysis of 4365 base pairs aligned sequence from nuclear and mitochondrial genes including new sequence data from the internal transcribed spacers (ITS1 and ITS2) of the nuclear ribosomal DNA, the sequences of three growth hormone introns (GH1C, GH2C, GH2D) and the sequences of the ATPase6 and ND3 genes of the mtDNA. Phylogenetic analysis of the combined data set gives strong support to a close relationship between pink and chum salmon and between coho and chinook salmon.