ON THE KARYOLOGICAL DIFFERENTIATION IN CA UCASIAN POPULATIONS OF COMMON VOLE (RODENTIA, CRICETIDAE, MICROTUS)

This study of karyotypes of 24 specimens of common voles from 8 locali ties of the Caucasus and the Cis-Caucasian region was carried out. The specimen of 54-chromosome M. rossiaemeridionalis from Stavropol distr ict has the standard karyotype (NF = 56) without any rearrangements. A ll other specimens from the Caucasus belong to 46-chromosome M. arvali s form ''obscurus''. The interpopulation variation determined by the v ariability of fundamental number and the morphology of Y-chromosome wa s noted. Three variants of karyotype were revealed: 1) NF = 72, Y-chro mosome is meta-submetacentric; 2) NF = 72, Y-chromosome is acrocentric ; 3) NF = 74, Y-chromosome is acrocentric. The review of chromosome va riability in the Caucasian populations of M. arvalis (2n = 46) caused by the variability of the morphology of small pairs of autosomes and Y -chromosome is compiled. The variability of heterochromatine localizat ion in the karyotype of common vole M. arvalis form ''obscurus'' in th e Caucasus is described. The results are evaluated in taxonomic and ev olutionary aspects.