Peculiarities of Early Ontogeny of Dwarf Forms of Arctic Charr Salvelinus alpinus Complex (Salmonidae) from Lakes Tokkoand Bol’shoe Leprindo (Transbaikalia). 2. Reciprocal Hybridsстатья
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Аннотация:—Growth, peculiarities and anomalies of the ossification and development of skeletal elements, aswell as body proportions and meristic characters of laboratory-reared larvae and fry of two lacustrine dwarfforms of Arctic charr Salvelinus alpinus complex from lakes Tokko and Bol’shoe Leprindo (Transbaikalia)were studied. Retardations of the formation of blood cells, anomalies of morpho- and osteogenesis, andincreased mortality of unhatched embryos, free embryos and prelarvae of reciprocal hybrids were revealed.Initial characteristics of prelarvae, linear growth, rate of osteogenesis, body proportions, and colouration ofhybrid individuals matched matroclinal developmental pattern. Heterochrony of the ossification of vertebralcentra was revealed in prelarvae of the hybrid between females from Lake Tokko and males of the deep-waterform from Lake Bol’shoe Leprindo. Their ossification was displaced to an earlier stage in the typical ossification and differentiation sequence of skull bones and fin rays, which indicates the presence of respective regulator in parental genome. Such effect was not observed in reciprocal hybrid; however, it demonstrated earlierossification of predorsalia than the pure form from Lake Bol’shoe Leprindo. The formation of morphologicalfeatures in the ontogeny of hybrid larvae and juveniles as compared with parental forms was traced. All lethalanomalies of reciprocal hybrids and non-lethal anomalies influencing their viability as well as accelerated useof yolk by hybrids between the females from Lake Bol’shoe Leprindo and males from Lake Tokko, whichresulted in mass mortality of prelarvae and weak development of the skeleton of early larvae are considered asthe elements of post-zygotic reproductive isolation between pure forms of gen. Salvelinus from the two lakes.This isolation is obviously incomplete since part of hybrid individuals developed normally, though their fertility remains unknown.
