EVOLUTION OF THE CYTOCHROME-B GENE FRAGMENT FROM MITOCHONDRIAL-DNA INSOME BAIKALIAN AND NON-BAIKALIAN COTTOIDEI FISHES

Partial nucleotide sequences of the cytochrome b [EC 1.6.2.2] gene loc ated in mitochondrial DNA of 29 species of Cottoidei fishes (16 Baikal ian and 13 non-Baikalian species) were determined. Pairwise analysis d emonstrated that the gene evolution in Baikalian species may be charac terized by a higher ratio of substitution mutations to synonymous subs titutions. The causes of this difference are discussed. One of the pos sible explanations may be an enhanced rate of accumulation of substitu tion mutations accompanying intense speciation. Analysis of phylogenet ic trees and of nucleotide sequences testifies to the recent origin of the Baikalian Cottoidei complex from one or a limited number of ances tral forms. Its evolutionary age does not exceed 2 million years.