Abstract:
Two Male specific Y chroinosome (MSY) markers, a single nucleotide polymorphism (SNP) A/G and a microsatellite marker SRYM18 were used to study genetic relationships and Y chromosome diversity of 35 distinct sheep populations. Five MICcrosatellite alleles of sizes l3l bp, 139 bp, lfll bp, 143 bp, and I45 bp were detected. The I43 hp allele was distributed in both the thin»tailed and fat-tailed sheep and across geographical regions. lt was the most common on the continent with a frequency of 72.9%. The l4l bp allele was most common in the thin-tailed sheep compared to the fat-tailed sheep with a continent-wide frequency of l9.7%. The 145 bp allele was only found in the fat-tailed sheep at a frequency of 8.8%. The 131 bp-and the 139 bp alleles were the least common on the continent with a respective frequency of less than 1%. Based on the distribution of these alleles in populations, the most diverse population was the thin-t'ailed~Djallonké of Senegal and Maure of Mali. The lowest Y chromosome diversity was observed glfl the three fat- tailed populations, Gumuz, Sekota and Tukur of Ethiopia which had only one allele type, the 143 bp. Other than these five populations all the other populations had at least two different alleles. SNP screening was less informative as only the A allele was detected. Three haplotypes l4l/A, I43/A and l45/A with a respective frequency of 16.7%, 72.5% and 10.8% were constructed based on the data from the two markers. Haplotype 143/A was most common in the fat-tailed sheep of East Africa (90.5%) and Southern Africa (60.0%) while haplotype I41/A was most common in the thin-tailed sheep of West Africa (87.5%) This study shows that genetic ‘ll l-Chromosome Diversify and Genetics of African Domestic Sheep I03 variations on the Y chromosome exists within African sheep and corroborate existing archaeological information suggesting distinct origin of the West African thin-tailed and the fat-tailed sheep of East and Southern Africa.
