Lack of mtDNA variation among remote middle Volga and upper Ural brown trout suggests recent and rapid recolonization

Abstract

Brown trout populations from the middle Volga and upper Ural drainages in the Russian Federation were analyzed with respect to their inter-relationships and phylogenetic status using complete mtDNA control region sequences and 10 microsatellite loci. Among 56 individuals from eight populations (six from the middle Volga and two from the upper Ural drainages) only one haplotype was detected: Iran1 from the Danube phylogenetic lineage. This haplotype is very frequent in the southern Caspian basin in Iran. Given the high diversity of haplotypes in northern Iran, in contrast to the complete domination of the Iran1 haplotype in our study, it seems likely that Iran1 reached the middle Volga and upper Ural drainages as a consequence of colonization from the southern Caspian basin. In contrast to the mtDNA analysis, a more pronounced differentiation was observed among the studied populations on the basis of microsatellite DNA data. Based on this result, it is proposed that each population should be treated as a distinct management unit in the context of future conservation activities.