Сравнительная кариология и становление изолирующих механизмов и родe Marmota. [Caryologie comparative et mécanismes d'isolement évolutif du genre Marmota. Comparative karyology and development of the isolation mechanisms in the genus Marmota (Rodentia, Mammalia].

Résumé

Marmota baibacina, M. menzbieri and three geographically isolated forms of M. caudata have 2n=38 and NF=70. Karyoptypes of nearctic marmots are entirely homologous, the difference in chromosome number of different species appearing as a result of Robertsonian fusion. The VIIth pair of chromosomes present in palearctic marmots is absent in nearctic species. Taking into acount the Pliocene age of the genus Marmota in America and Pleistocene age of that in Eurasia, it may be suggested that sympatric character of spreading and difference in chromosome numbers of nearctic forms reflects their more ancient history as compared with the allopatric mode of spreading and identical chromosome numbers of palearctic species. The Middle Asian marmot species are well differentiated in colour and vocal sings. Apparently these ethological mechanisms maintain the isolation between the species under question in the zones of areas joint. Sharp differences in vocal sings between the populations of M. caudata from Pamir and from Talass (W. Tian Shan) have been found. It is very likely, that the accumulation of behavioural differences in isolated groups, followed by the meeting of vicarious subspecies, may result in their ethological isolation. Differences in chromosome numbers have been found statistically between populations of M. caudata from Hissar, Pamir and Talass. A suggestion is put forward on the existence of circular areals for Pleistocene marmots on the basis of analysis of ancient and modern areals of palearctic Marmota.