Вселение байкальской нерпы (Pusa sibirica Gm.) в озеро Байкал и современные угрозы популяции в связи с изменением климата (обзор). Сообщение 2. Палеоусловия эволюции байкальской нерпы в оз. Байкал и современные угрозы в связи с потеплением климата

Abstract

Message 2 gives the possible timing of the introduction of the Baikal seal into Lake Baikal. Baikal in terms of geological history and paleoclimatic conditions. Based on the analysis of peleoclimatic reconstructions, as well as molecular genetic studies of fish, the following statements were put forward: 1. An ancestor of the Baikal seal settled in deep-water and already cold-water Baikal with an established thermohaline type of circulation. 2. Prior to introduction, the ancestral form lived in polar conditions and was to some extent adapted to ice conditions. 3. The development and consolidation of structural-functional and other adaptations to the specific conditions of the settlement reservoir, probably, quickly formed a new species. 4. By the time of settlement, the lake had an ichthyofauna capable of meeting the trophic needs of a large fish-eating mammal. 5. The evolution of golomyankas (Comephorus) – the main food of the Baikal seal - and the formation of the Baikal seal as a species, could take place in parallel. For this reason, the behavior of golomyankas and the diving strategy of seals turned out to be strictly coordinated. 6. The invasion of the ancestral form occurred at the end of the late Pleistocene, possibly in the Zyryansk time, through dammed glacial lake systems and the Yenisei-Angara rivers. Changes in the behavior of the Baikal seal, which are already occurring in response to warming and changes in living conditions, are described. In particular, the shortening of the ice period has already led to a change in the behavior of animals (due to the lengthening of the molting period). The potential threats to the seal population, which may arise if the negative forecasts of climatologists begin to come true, are also assessed. In particular, if the duration of the ice period is reduced to two months, this will certainly have a negative impact on the reproduction of the population, and, as a result, on its demography. There is a high probability of a change in the habitat of seals during the birth and rearing of puppies. The population will decrease, but the rest of the animals will adapt, perhaps be better provided with food, and the population will continue to exist at a different level (in terms of numbers). On the whole, an alarming, but not tragic picture of the immediate future of this species of seals emerges.