Spatial Differentiation of Whitespotted Char × Dolly Varden Hybrids (Salvelinus leucomaenis × S. malma, Salmonidae) and Their Parental Char Species in the Utkholok River (Northwestern Kamchatka). Specific Biotopes as an Indicator of Microevolutionary

The results of the study of the distribution of whitespotted char × Dolly Varden hybrids (Salvelinus leucomaenis × S. malma) and their parental species in the Utkholok River (northwestern Kamchatka) are given. The localization of sexually mature individuals after spawning in the river channel in the pre-winter period (September–October) is presented. Qualitative differences have been revealed in the characteristics of the water flow and bottom substrate in the biotopes preferred by the chars and their hybrids. A characteristic feature of fish distribution is the position of individuals in a water flow, which provides maximum access to drift food particles for effective post-spawning recovery and preparation for wintering. It has been found that the biotope of whitespotted char × Dolly Varden hybrids is unique and differs from those of their parental species: the three groups were able to reduce the tension of feeding relationships based on spatial distribution. The results provide additional evidence of the successful course of microevolutionary processes, including the adaptation of the hybrids to their own biotope in the ecosystem. There is reason to believe that the interspecific relationships of the hybrids and parental species in the Utkholok River are nonantagonistic and their stable coexistence with continued selection, as well as the stabilization of the developed adaptations, are possible.