Abstract: The domestic yak (Bos grunniens) is the most important domesticated bovine species in the Qinghai-Tibetan Plateau. In the present study, the cytochrome b (Cyt b) gene partial sequences (540 bp) of 27 domestic yaks (20 sequences determined in our study and 7 sequences cited in GenBank) were analyzed. Combined with the homologous fragments of other bovine Cyt b sequences in GenBank, the phylogenetic trees of Bovinae were reconstructed by Neighbor-Joining (NJ) methods with Ovis aries as outgroup. Sequence analysis showed that, among 540 sites compared for 27 domestic yaks, 9 variable sites (1.67% of 540 sites) and 5 different haplotypes were observed, showing very low mitochondrial genetic diversity in domestic yaks. The sequence divergence and divergence time between yak (Bos grunniens/Bos mutus) and American bison were 3.33% and 1.48-1.85 million years, respectively, lower and shorter than those between yak and genus Bos (Bos taurus/Bos indicus). Phylogenetic analysis showed that yak and American bison close clustered into one embranchment, while Bos taurus and Bos indicus independently clustered into another embranchment. Our results supported that the domestic yak was domesticated from a primitive yak different from the present wild yak and the yak should be classified as an independent genus Poephagus in Bovinae.
S.P. Li , H. Chang , G.M. Song , G.L. Ma , H.Y. Chen , D.J. Ji and R.Q. Geng , 2007. Molecular Phylogeny and Taxonomic Status of Domestic Yak Inferred from Cytochrome B Gene Partial Sequences. Journal of Animal and Veterinary Advances, 6: 1495-1499.