Charrs of the genus Salvelinus (Salmonidae): hybridization, phylogeny and evolution

Abstract

Evolutionary history, systematics and taxonomy of charrs of the genus Salvelinus and especially of the representatives of the S. alpinus - S. malma species complex remain confused that is connected with a substantial ecological and morphological flexibility of this group and with supposed ancient hybridization between some taxa. For the analysis of phylogenetic relationships and introgressive hybridization between the species of the genus Salvelinus including three endemic species from Lake Elgygytgyn and all main representatives of the S. alpinus - S. malma species complex, nucleotide sequences of mtDNA control region (960 bp) and two nuclear genes (ITS1 (581 bp) and RAG1 (899 bp)) were analyzed. The differences in the topologies of individual gene trees, among others reasons, were connected with incomplete lineage sorting and historical introgressive hybridization between certain taxa. Several cases of mtDNA capture by different taxa and phylogenetic groups were proposed. In particular, the following taxa participated in introgressive hybridization: northern Dolly Varden S. m. malma, representatives of the S. alpinus complex (including mainly Taranets charr S. a. taranetzi), southern Dolly Varden S. m. lordi from North America and bull trout S. confluentus. Main phylogenetic groups of the S. alpinus - S. malma species complex were revised. The origin and phylogenetic relationships of southern Dolly Varden from North America were not unambiguously defined. We proposed that introgressive hybridization had an important role in the evolutionary history of charrs, in particular, in the appearance of a high level of morphological, ecological and taxonomical diversity.