ABSTRACT
Samples from 11 populations of the Arctic char of the North-European part of Russia belonging to the anadromous and resident forms and two samples from Lake Sobach'e (Taimyr) were studied. The nucleotide sequence of the mitochondrial COI gene was determined in 60 individuals. In the majority of populations, the same COI haplotype was found. In some populations of the resident chars, haplotypes differing from the widespread haplotype in a single nucleotide substitution were found. The obtained genetic data give no reason to distinguish the resident form of the Arctic char from lakes of Karelia and the Kola Peninsula as an independent species, Salvelinus lepechini. The adaptation of the Arctic char to the unstable environmental conditions is ensured primarily by its phenotypic plasticity.
