CHROMOSOMAL REARRANGEMENTS IN A SOMALI WILD ASS PEDIGREE, EQUUS AFRICANUS-SOMALIENSIS (PERISSODACTYLA, EQUIDAE)

Chromosome analyses were conducted or, 15 animals in a pedigree of Som ali wild ass, Equus africanus somaliensis. G- and C-banded karyotypes are presented for the first time on this endangered species. The diplo id number ranged from 62 to 64. Numerical chromosomal variation was th e result of a centric fission which was accompanied by a heterochromat ic deletion. The fission polymorphism involved acrocentric elements 19 and 21 as determined by G-banding. These autosomes are homologous to those involved in centric fission/ fusion polymorphisms in other equid s: E. asinus (domestic donkey), E. hemionus (onager), E, kiang (kiang) , and E. burchelli (common zebra). Banding analyses also revealed a pa racentric inversion polymorphism in submetacentric chromosome pair 2 o ff. a. somaliensis. Both the centric fission and paracentric inversion polymorphisms involved heterochromatic regions. One individual was fo und to be heterozygous for two de novo chromosomal rearrangements: a c entric fission (involving acrocentric elements 19 and 21) and a hetero chromatic deletion of chromosome 2.