Analysis of the Genetic Diversity and the Phylogenetic Evolution of Chinese Sheep Based on Cyt b Gene Sequences

The complete sequences of Cyt b gene from 20 individuals belonging to eight Chinese indigenous sheep breeds and one foreign breed were studied. The results showed that the hapolotype diversity of Chinese sheep breeds was 97.1%. The mean nucleotide composition of all the sequences was 27.1% T, 28.5% C, 31.4% A, and 13.0% G. The nucleotide diversity was 0.602%. A total of 43 mutation sites were detected, including 40 transitions and 3 transversions. Fu's test of selective neutrality showed that the sheep populations had no population demographic expansion (0.10 > P > 0.05). The different clustering methods, namely neighbor-joining, minimum evolution, and unweighted pair group method with arithmetic means, all showed a similar result, which indicated that Chinese local sheep had three maternal resources.