中国3个牛种cyt b基因多态性及其系统发育研究

Diversity and phylogenetic analysis of the cyt b gene of three Chinese bovid species

基于mtDNA cyt b基因全长序列,对中国黄牛、牦牛和水牛的遗传多态性和系统发育关系进行了分析。结果表明,中国黄牛、牦牛和水牛cyt b基因序列中碱基A和T的含量均比较高,A+T的平均含量分别为56.6%,58.2%和56.0%。黄牛在cyt b基因全长序列具有较丰富的核苷酸多样性(Pi=0.016 84),水牛的核苷酸多样性相对贫乏(Pi=0.003 51),牦牛的核苷酸多样性介于二者之间(Pi=0.012 28)。中国黄牛与牦牛和欧洲野牛之间的亲缘关系相对较近,而与水牛间的亲缘关系则相对较远,黄牛有普通牛和瘤牛2个母系起源;中国牦牛和斑腾牛以及羯牛的亲缘关系相对较近;中国水牛和沼泽型水牛具有较近的亲缘关系,也可能有2个或者2个以上的母系起源。

Genetic diversity and phylogenetic relationships of Chinese yellow cattle, yak and buffalo were analyzed based on DNA sequences of the cytochrome b gene. The content of A/T was comparatively higher in sequences of the cyt b gene of yellow cattle,yak and buffalo,compromising 56.6%,58.2% and 56.0% of the total nucleotides on average respectively. The nucleotide diversity of the cyt b gene of Yellow cattle was higher （Pi=0. 016 84） than that of yak （Pi=0. 012 28） and buffalo （Pi=0. 003 51）. Phylogenetic tree of the cyt b gene haplotypes among three bovid species was constructed by using Neighbor-joining algorithms. The results indicated that the phylogenetic relationship of Yellow cattle and yak was comparatively closer than that of yellow cattle and buffalo. Yellow cattle showed closer phylogenetic relationship to European bison and were originated from Bos taurus and Bos indicus,while Yak showed closer relationship with Bos javanicus and Bos gaurus. The three individuals of Chinese buffalo examined were phylogenetically related to Bubalus bubalis ＂and fell into two distinctive clades in maternal lineage.