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Russian Journal of Theriology

Hybrid zones of house mice of genus Mus (Rodentia, Muridae) in Russia and neighbouring countries: role of hybridisation in evolution of commensal taxa // Russian J. Theriol. Vol.3. No.1: 2532 [in English].

The significance of hybridisation in the evolution and diversification of commensal taxa of Mus musculus s.l. species group is discussed. Allozyme analysis has shown that Transcaucasian populations of commensal house mice possess an admixture of musculus and domesticus genes. This region is either a zone of secondary contact between musculus and domesticus, with very wide introgression of domesticus genes into the genome of musculus, or these are relict populations descended from non-differentiated forms with ancestral polymorphism. The main feature of this zone is the unusually large extent of domesticus genes, which occur throughout the entire Transcaucasia (about 350 000 km 2 ). Data and observations favour the view suggest that Transcaucasian house mouse populations are relicts of an early-differentiated form of M. musculus, preserving much of the ancestral gene pool. The second possible hypothesis is that populations of Transcaucasia are result of hybridisation of ancient not finally differentiated forms of house mice. It is possible that ancient oriental lineage and ancient form of musculus were colonised the Transcaucasia and mixed in this territory. The Adzharian populations would then be a product of contact between these forms and early of fully differentiated M. domesticus from Turkey. Large zones of hybridisation are present also in other regions of Asia. Analysis of hybrid populations of house mice in Russia demonstrates the particular significance of hybridisation in the evolution of commensal taxa. This enhanced role in commensals is linked to their unique ability to expand their geographic ranges through human agency and even survive as commensals in areas that are beyond their physiological tolerance. KEY WORDS: hybridisation, Mus musculus species group, commensalism, hybrid zones.