[Karyotypes and chromosomal differentiation of two species of the genus Tachyoryctes (Rodentia, Tachyoryctinae) from Ethiopia]

Abstract

Karyotypes of two species of genus Tachyoryctes from four localities in the Bale Mountains National Park, Ethiopia, were analyzed. T. splendens has 2n = 48, NFa = 65-86. Variations of the autosome arm number are determined by different numbers of autosomes with additional heterochromatin arms (7-17). Karyological analysis indicated that the cytogenetic structures of T. splendens from the localities studied was unique, which might result from formation of the karyotypes optimal for the given habitats. T. macrocephalus has 2n = 50, NFa = 62. A high conservatism of the number and size of C-positive heterochromatin blocks reflects the extreme specialization of T. macrocephalus endemic for the Bale province and occupying a limited ecological niche. Homology of G-banding patterns of several chromosomes and chromosome arms demonstrated that karyotypes of T. splendens and T. macrocephalus were formed from the common ancestral karyotype through different rearrangements in some chromosomes.