Аннотация:Within the sympatric evolution framework a range of ecological variables are considered as potential initiators and controllers of the diversifcation process. Here, we identify the proximate factors providing the reproductive isolation among sevensympatric ecomorphs of the genus Salvelinus charr dwelling in the Lake Kronotskoe basin (North-East Asia). We demonstratethat the slope profle of the lake tributaries determining the water fow velocity and position of the groundwater dischargesserves as a barrier between the reproductive sites of the ecomorphs and provides the basis for selective pressure afecting theLake Kronotskoe fsh during spawning. The main characteristic under selection is a migratory ability, which is determinedby the swimming performance and the amount of energy reserved in the body and depends on fsh morphology and physiology. The fex points indicating abrupt slope changes along the spawning watercourse restrict the upstream migration ofthe groups having a comparatively low swimming performance and energy reserve. A thorough analysis of the ecomorphs’migratory and spawning activity indicated two energy expenditure strategies: the fsh could invest most of the energy eitheron migration or spawning. Our fndings supported with data on fsh ecology, morphology, and thyroid hormone status allowus to put forward a following hypothesis. We suggest that the interplay of spatially heterogeneous environmental variablesafecting life history decisions via ecomorphological and physiological traits could serve as a trigger for the reproductiveisolation among the ecomorphs in a single ecosystem.Также был проведен анализ лингвистических, стилистических и структурных особенностей статей в данном журнале для подготовки публикации