Phylogenetic relationship of mitochondrial DNA in salmonids of the subfamily Salmoninae: analysis of the cytochrome b gene sequences

On the basis of comparison of the cytochrome b gene nucleotide sequences from genetic databases, the possible phylogenetic relationships of mitochondrial DNA (mtDNA) among all major lineages of Salmoninae (Brachymystax, Parahucho, Salvelinus, Salmo, Parasalmo, and Oncorhynchus) were examined. Three different phylogenetic methods (UPGMA, NJ, and ML) yielded phylogenetic trees of essentially the same topology: (((Brachymystax, Parahucho), Salvelinus, Salmo), (Parasalmo, Oncorhynchus)). The results obtained using the maximum parsimony method were less clear. Apparently, the divergence of the main salmonid lineages occurred during a relatively short time period; hence, the number of synapomorphs marking the order of their divergence was extremely low. This may account for the relative failure to use the maximum parsimony method of phylogenetic reconstruction. The problem of concordance of mtDNA and species phylogenetic schemes is discussed. Their discrepancy in salmonids may be caused by interspecific introgressive hybridization.