THE HOUSE MICE, MUS MUSCULUS S. L., HYBRID ZONE OF TRANSCAUCASUS

A description of the hybrid zone of house mice species of the Transcau casus is given on the basis of allozymic data and morphological charac ters. It is demonstrated that the hybrid zone in the Transcaucasus is formed by three parapatric species: M. musculus, dwelling mainly in th e north Caucasus; M. domesticus, inhabiting the area from western Tran scaucasus to eastern Ciscaucasus; M. praetextus, widely represented in steppe regions of Azerbaijan. The main features of this hybrid zone a re: (i) unusually high range of gene introgression throughout the enti re Transcaucasus; (ii) a sharp boundary between M. musculus and the ge ne introgression zone between M. musculus, M. domesticus, and M. praet extus, stretching along the climatic boundary between continental and subtropical regions; (iii) the existence of a transitional zone in the Central Transcaucasus between M. praetextus and M. domesticus. The re sults obtained are discussed with regard to the hybrid zones of Europe and Eastern Asia. Two main features of Asian hybrid zones are emphasi sed: their unusually large width as compared to European examples and their localisation in climatic zones similar to the subtropics.