The riverine dwelling groups of endemic Dolly Varden (Salvelinus malma, Salmonidae) morphs from lake Kronotskoe (Kamchatka, Russia)

Abstract

Dwarf males and fluvial groups were found in the population structure of endemic Dolly Varden (Salvelinus malma) morphs dwelling the Lake Kronotskoe basin. Apart from the lacustrine-riverine charrs, dwarf males and fluvial groups stay in the vicinity of their own spawning grounds for their whole life at the upper reaches of the lake tributaries. Fluvial males and females were found only for white charr morph which can be defined as the biggest generalist among the endemic Lake Kronotskoe charrs. It was found that propensity for dwarf males' formation for different morphs of nosed charrs corresponds to the complexity of the river habitats i.e. amount of the covers and lateral branches. No fluvial individuals were registered for longhead charr regarded as one of deep-specialised predatory morph. It was revealed that all riverine dwelling groups are defined by a similar lifestyle; however they are distant from each other by body shape and closer to the corresponding morph representatives rather than to each other or to the ancestral Dolly Varden. The morphology data underlines that riverine dwelling groups are an inherent part of each morph and should be considered as a life strategy variance, but not as distant morphs. The unidirectional patterns of the morphological development for riverine-lacustrine and fluvial groups point to the heritability bases for those traits. The conserving of specific morphology within the fluvial groups lets us suggest an approach for allowing a reconstruction of the populations heavily damaged by anthropogenic activity.

Keywords

• fluvial forms and dwarfs
• life strategies
• microevolution
• population recovery
• population structure