The Origin of Coregonid Fishes of the White Sea Kuloi Plateau
Sendek, D.S.; Novoselov, A.P.; Studenov, I.I.; Gurichev, P.A.
The White Sea Kuloi plateau is a territory (about 25, 000 km2) at the southeastern part of the White Sea basin. On the mainland, it is confined by the rivers of the Northern Dvina, the Pinega, and the Kuloi. The fauna of coregonid fishes on that territory is represented by European whitefish (Coregonus lavaretus) and local cisco (genera Coregonus), the species definition of which is still under discussion. We have investigated genetic variability of several whitefish and cisco populations by 29 allozyme loci with the aim to identify the ways of their formation during the postglacial period. Comparison of four cisco populations with several populations of typical vendace (Coregonus albula) from the basin of the Baltic Sea and hybrid forms of vendace and least cisco (Coregonus albula x Coregonus sardinella) from the Pechora has shown that the cisco of the White Sea basin belongs to the species Coregonus albula. Most probably, those populations were formed with no impact from least cisco, which did not reach the basin of the White Sea during the period of postglacial resettlement to the west. The results of comparative studies of whitefish populations have shown that most populations of the White Sea Kuloi plateau emerged due to postglacial colonization of water bodies by common periglacial whitefish race, which usually features lower number of gill rakers and dwells in partly desalinated sea water. The origin of the high-density rakered population from the central part of the White Sea Kuloi plateau—having the biggest deviations from the other populations analyzed in that region—can be explained by both a sympatric and allopatric speciation model.