Secondary contact, hybridization, and diversification in Arctic charr ( Salvelinus alpinus (L.) species complex) from lakes of the Norilo-Pyasinskaya water system, Taimyr: how many forms exist there?

Arctic charr Salvelinus alpinus (L.) complex has two or more sympatric forms in many lakes representing a subject for discussions on the mechanisms of their origin and taxonomic status. To determine the number of sympatric forms in three large lakes of the Norilo-Pyasinskaya water system (Taimyr) and their reproductive and phylogenetic relationships, 17 microsatellite loci, sequences of the mtDNA control region, and several morphological characteristics were analyzed. Our data indicate that eight reproductively isolated forms inhabit lakes Lama and Kapchuk, and at least three forms are distributed in Lake Sobach’e. The origin of the forms is associated with the secondary contact and hybridization of the European and Siberian phylogenetic lineages. The same names of the forms from different lakes of Taimyr and Chukotka, for example, Boganida charr and Dryagin’s charr, may reflect their certain morphological similarity, but rarely close relationships. Our data indirectly indicate that introgressive hybridization and biogeographical changes of the lakes within the region in the last glacial and post-glacial periods played a significant role in the formation of a high Arctic charr biodiversity. The problem associated with systematics, taxonomy, and conservation of the forms in Taimyr lakes is complex and should be solved gradually.