Abstract: Totally 712 bp fragments of mitochondrial cytochrome b gene of 7 species in 4 genera of Schizothoracinae fishes in Xinjiang were amplified and sequenced. For the Cyt b gene, the average nucleotide contents of T, C, A and G were 30.1%, 27.4%, 25.6% and 16.9% respectively. There were 201 variable sites, of which 162 were parsimony-informative sites, their sequence variability was 22.8%, the transition/transversition was 15.03, and the nucleotide substitution occurred mostly at the third position. Three molecular phylogenetic trees were constructed with different methods, in which the neighbor-joining (NJ) tree and maximum parsimony (MP) tree were based on Kimura 2-parameter method, and the maximum likelihood (ML) tree was based on the best nucleotide substitution model. The results show that there were the close genetic relationships among the primordial-grade Schizothoracinae species and among the specialized-grade Schizothoracinae species. It is referred from the molecular evolution rate that the divergence of the 7 Schizothoracinae species occurred during the period from the late Pliocene to the Miocene with the uplift of the Qinghai-Tibet Plateau.

Key words: Schizothoracinae, mitochondrial cytochrome b gene, molecular phylogeny, Xinjiang