On Widening the Hybrid Zone for Chars of Genus Salvelinus, Kundscha S. leucomaenis and Northern Dolly Varden S. malma (Salmonidae), in Rivers of Kamchatka Peninsula

Abstract

The data on widening the zone for hybridization between the chars of the genus Salvelinus, kundscha S. leucomaenis and northern dolly varden S. malma (Salmonidae), in rivers of the Kamchatka Peninsula are reported. If the hybrids between the kundscha and the northern dolly varden could be previously observed only in the Utkholok River in the northwest of the peninsula, the mass hybridization between these species have occurred in two more nearby rivers, the Kvachina and Snatolveem Rivers since 2009. A microsatellite analysis has shown that hybrid specimens are characterized by intermediate values for allelic diversity, when compared to that in the representatives of parental species, while the mean expected heterozygosity values for hybrids are higher than that in Dolly Varden and kundscha fish. The analysis results for maternal inheritance in hybrid specimens from the Kvachina River coincide with that obtained in the surveys previously performed in the Utkholok River. Thus, the same haplotype specific for the kundscha fish was revealed in all the hybrid specimens, which can indicate that the hybrids originate from kundscha females and Dolly Varden males. The appearance and coloration of kundscha × northern dolly varden hybrids in the Kvachina and Snatolveem Rivers are similar to that in the specimens in the Utkholok River. Rather similar chacteristics of hybrid specimens in all three rivers can give reason to consider that a mechanism of their occurrence in the Kvachina and Snatolveem Rivers is simalr to that in the Utkholok River, since the kundscha eggs are inseminated by the Dolly Varden dwarf males. The increased local biological production of rivers due to increased sizes of spawning stocks of pink salmon Oncorhynchus gorbuscha along with large-scale climate changes in the North Pacific are considered as a possible cause of disturbances of isolation between species. It is quite probable that these two factors have contributed to improving the environmental conditions for fattening the Dolly Varden fish in the freshwater phase of their life cycle and, as a resultl of this process, increasing the number of Dolly Varden male fish matuaring in the river.