Chromosomal reduction in an Okapi pedigree (Okapia johnstoni)

The karyotype of a female okapi showing 2n = 44 has been investigated by G-R-C and Ag-NOR banding methods. This animal is the offspring of a captive female and a wild-caught male, which are both heterozygotes showing 2n = 45 with centric fusion between two unequal-sized acrocentric chromosomes. The okapi karyotype was arranged according to the cattle standard karyotype in consideration of the high degree of banding homologies found between the two species. The reduction from 2n = 46 to 2 = 45 and 2n = 44 is the result of a Robertsonian translocation involving cattle equivalent chromosomes 4 and 26. Other autosomal rearrangements, like centric fusions and a tandem translocation, as well as structural changes in the X and the Y chromosomes, are tentatively identified