GENETIC-STRUCTURE AND ORIGIN OF THE TETRA PLOID TOAD BUFO-DANATENSIS PISANETS, 1978 (AMPHIBIA, BUFONIDAE) FROM CENTRAL-ASIA - DIFFERENTIATION OF GEOGRAPHIC FORMS AND GENETIC-RELATIONSHIP BETWEEN DIPLOID AND TETRAPLOID SPECIES

A hierarchical system, consisting of several levels of genetic diverge nce, is formed by distribution of genetic distances between diploid ta xa of the green toad species complex (subspecies Bufo viridis viridis - B. v. turanensis and species B. viridis - B. sp.) and taxa represent ing western (B. viridis s. l.) and eastern (B. raddei) Palearctic regi ons. Formally, genetic differentiation of the tetraploid toad B. danat ensis from the parapatric diploid species reaches the species level, G enetic diversity of the tetraploid species is more than twofold higher than the total diversity of two modem diploid species. This suggests that B. danatensis was formed with the participation of other unknown species in the past. The polyploid species B. danatensis is assumed to have originated by hybridization of two Species groups that arose app roximately 2.6 million years ago in Mediterranean and Central Asian re gions of the western Palearctic. The genetic heterogeneity of geograph ical populations of the polyploid species indicates its polyphiletic o rigin. The heterogeneity range suggests that formation of the tetraplo id species continued for a very long period (about 1 million years).