Abstract: Mitochondrial DNA (mtDNA) Dloop sequences of 23 individual horses from Lhasa and Zedang in Tibet were analyzed. The results reveal 16 unique haplotypes, 32 polymorphic sites (31 transitions and 1 deletion), which account for 9.27% of the total number of sites in DNA sequence analyzed. The hapl otype diversity (h) and nucleotide diversity (π) were 0.93±0.04 and 2. 51%±0.16%, respectively, showing that abundant mitochondrial genetic diversity exists in Tibetan horses. Moreover, the phylogenetic analysis and multidimension al scaling analysis were performed based on the mtDNA sequences of Tibetan horses and the related Eurasian horse populations. The results show that Tibetan horses have widespread maternal origin. Tibetan horses are closely related to the populations from Near Asia, Central Asia and Europe, whereas they are less related to the populations from Mongolia and Korea.

Key words: Tibetan horses, mitochondrial DNA, D-loop, genetic diversity, phylogenetic analysis