Chromosome number of Severtzov's sheep (Ovis ammon severtzovi): G-banded karyotype comparisons within ovis.

Abstract

Severtzov's sheep (Ovis ammon severtzovi; Nasonov 1914) has a 2n = 56 diploid chromosome number and a karyotype consisting of two pairs of biarmed and 25 pairs of acrocentric autosomes, a large acrocentric X, and a minute biarmed Y. The G-banding patterns of the largest pair of biarmed chromosomes were identical to those of the largest biarmed chromosomes in all wild and domestic sheep of the genus Ovis. The banding patterns of the second pair of biarmed chromosomes were identical to the third pair of biarmed chromosomes in all sheep of the genus Ovis with 2n = 54 and to the third largest pair of chromosomes in the 2n = 52 karyotype of the Siberian snow sheep (O. nivicola). The G-banded karyotype of Severtzov's sheep is consistent with all subspecies of argali (O. ammon spp.) that have been karyotyped. Numerical ascription of acrocentric chromosome equivalents based upon the fundamental karyotype of Ovis that gave rise to the biarmed chromosomes of severtzovi are 1 and 3, and 5 and 11 for the largest and second largest biarmed chromosomes, respectively. Based upon diploid chromosome number and G bands, Severtzov's sheep should be considered a subspecies of argali and not a urial.