THE RANGES OF MARMOTS (MARMOTA, RODENTIA) IN THE SOUTHEAST OF WESTERN SIBERIA IN THE HOLOCENE

摘要

Three marmot species presently inhabit the southeast of Western Siberia: the Steppe marmot (Marmota bobak), the Grey marmot (M baibacina), and the Forest-steppe marmot (M.kastschenkoi). Based on both original and already published data on marmot remains from 43 Holocene localities and their historical distributions, we reconstructed the past ranges of all three species. Species discrimination of the marmot remains was conducted based on discriminant analysis of skull morphometric characters. The results suggest that, throughout the Holocene, the northern limit of marmot distribution extended to the southern border of the forest zone. In the Ob River valley, it stretched beyond the treeline and then crossed the Yenisei River at 56 N. In the end of the Late Holocene, the northern limit of marmot distribution in the Yenisei valley shifted southwest. Discriminant analysis of the remains from the Aidashinskaya Cave, Lower Chulym (56 12' N, 90 18' E) suggests the presence of grey and forest-steppe marmots. Neither species presently inhabits the area. A skull and a mandible from the Aidashinskaya Cave were attributed to the Grey marmot, while one skull and three mandibles to forest-steppe marmots. We can assume that, in the Late Holocene, the range of the Grey marmot decreased southeast, whereas that of the Forest-steppe marmot shifted westwards. The eastern range limit of the Steppe marmot seems to have been restricted to the Irtysh River valley. Range fragmentation of all three species could have been caused by farming spread over the last 100-150 years and the extirpation of the remaining marmot populations.