KARYOTYPES AND CYTOGENETIC DIFFERENTIATIO N OF 2 AFRICAN MOUSE-SPECIES OF GENUS MUS (RODENTIA, MURIDAE)

Karyotypes of two African mouse species, Mus mahomet, 2n = 36, NFa = 3 4 (34A + XA + YA) and Mus sp. A, 2n = 34, NFa = 32 (32A + XA + YA), fr om five localities of the Bale Mountains National Park, Ethiopia, were analyzed. In both species all autosomes contained C-positive pericent romeric blocks. In M. mahomet, heterochromatin blocks of different chr omosomes varied in size. In addition, the X chromosomes of both specie s contained a pericentromeric block and showed more intensive staining throughout the chromosome. The Y chromosome was two times larger in M us sp. A than in M. mahomet and C-positive in both species. Comparativ e analysis of G-banding patterns revealed a similarity with respect to nine autosomes and the X chromosome. Autosome 1 of Mus sp, A was demo nstrated to result from centromere-telomere fusion of two M. mahomet a crocentrics, The other five autosomes represent different linkage grou ps determining a specificity of the karyotypes. The karyotypes of M. m ahomet and Mus sp. A were also compared with that of M. musculus. The evolution of M. mahomet and Mus sp. A karyotypes was shown to have inv olved structural rearrangements in 10 and 12 autosomes, respectively. The high karyological divergence confirmed molecular phylogenetic data . The cytogenetic differences T of M. musculus C from M. mahomet and M us sp. A are high enough to different genera.