Phylogenetic analysis of smelts (Osmeridae) based on the variation of cytochrome b gene

Putative phylogenetic relationships between all smelt species inhabiting Russian waters were studied using RFLP and the data on divergence between nucleotide sequences of the mitochondrial gene encoding cytochrome b. All types of phylogenetic trees (NJ, MP, and Bayesian) displayed stable clustering into isolated groups corresponding to the division of the subfamily Osmerinae into three genera, Mallotus, Osmerus, and Hypomesus. It was demonstrated that the Mallotus phylum was the first to diverge from a hypothetical common ancestor of the smelts. Later, it divided into two clusters corresponding to the modern subspecies Mallotus villosus villosus and M. v. catervarius. The phylum of the genus Osmerus diverged later than the genus Mallotus and also divided into two clusters, one including O. mordax of the Pacific (Sea of Japan) and Arctic (Kara and Barents Seas) basins and the other, anadromous and resident ecotypes of the O. eperlanus from the Baltic Sea basin. The smelts of the genus Hypomesus is the youngest phylogenetic group among the taxa studied; it forms three individual clusters matching the species H. olidus, H. nipponensis, and H. japonicus. The proposed phylogenetic hypothesis is discussed from the standpoint of its compliance with the phylogenetic constructions based on the external morphological and osteological traits.