Morphological and Ecological Differentiation of Sympatric Forms of Arcrtic Charr Salvelinus alpinus (Salmonidae) in Lake Tokko (Northern TransbaikaliaстатьяИсследовательская статья
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Дата последнего поиска статьи во внешних источниках: 29 апреля 2021 г.
Аннотация:Based on data from 1997–2019, morphology, growth, feeding, reproduction and early developmentof Arctic charr from Lake Tokko (Olekma basin, northern Transbaikalia) were studied. Three charrforms, large, small and dwarf differing in growth rate were recorded in the lake. During the last years, the largeform disappeared, the small form became rare and the dwarf form became highly abundant; the proportionof old small and dwarf charr sharply decreased. The dwarf form differs in morphology from the small andlarge forms, which are morphologically similar. In the summer period of 1997–2001, the large form fed onfish, the small form fed mainly on amphibious insects (chironomid pupae), and the dwarf form fed onamphibious insects and benthos. Presently the small form transited to piscivorous and the dwarf form to predominantlyplanktivorous feeding. The dwarf form spawns from late July to mid-August at stony sites ofunderwater shore slope when water temperature is 5.0–6.5°С; laid eggs develop till late November–earlyDecember at water temperature decreasing to 3.0–3.5°С. According to data needing verification, the smallform spawns in late autumn, but some individuals spawn in summer at the same time as the dwarf form. Theresults suggest substantial, though incomplete reproductive isolation between the dwarf and the small forms.It is supposed that nowadays the degree of their introgressive hybridization has increased following anthropogenicchanges in population structure.