西藏牦牛mtDNA-Cytb及ZFY基因遗传多样性与系统进化分析

Analysis on Genetic Diversity and Phyletic Evolution of mtDNA Cytb & ZFY Gene in Tibetan Yak

为进一步了解西藏牦牛的遗传多样性及系统进化关系,通过对申扎、斯布、类乌齐和帕里4个西藏牦牛类群的mtDNA-Cytb基因及ZFY基因部分序列进行克隆及序列分析。结果表明:(1)西藏牦牛Cytb基因全长1140 bp,共发现SNP位点13个,核苷酸多样性(Pi)为0.00315,Tajima's D值为0.41410(P>0.10),共检出7种单倍型,单倍型多样性(Hd)为0.709;(2)ZFY基因第11外显子长596 bp,筛查出SNP位点22个,Tajima's D值为0.78287(P>0.10),发现3种单倍型,核苷酸多样性和单倍型多样性分别为0.001066和0.2976;(3)聚类分析及核苷酸同源性分析显示,西藏牦牛与家牦牛的核苷酸同源性最高,与美洲野牛及欧洲野牛的核苷酸同源性次之,与水牛及非洲水牛的核苷酸同源性最低。研究结果表明,西藏牦牛遗传多样性较丰富,进一步支持将西藏牦牛及家牦牛划为牛亚科中独立牦牛属的观点,及牦牛的原始祖先来自于亚欧大陆东北部的观点。

To better investigate the genetic diversity and phyletic evolution of Tibetan yak,this experiment was conducted to clone and analyze the polymorphism of mtDNA-Cytb and ZFY gene in 4 yak populations(Sibu,Pali,Leiwuqi and Shenzha yak)in Tibet.The results are shown as follows:1)the length of Cytb was 1140 bp,13 SNPs loci were discovered in Cytb gene.Nucleotide diversity(Pi)and Tajima's D value were 0.00315 and 0.41410(P>0.10),respectively.In addition,7 haplotypes were identified with the haplotype diversity(Hd)value being 0.709.2)The length of exon 11 in ZFY was 596 bp.22 SNPs loci were identified.The nucleotide diversity(Pi)and Tajima's D value of the ZFY sequence were 0.001066 and 0.7828(P>0.10),respectively.Furthermore,3 haplotypes were identified with the haplotype diversity(Hd)value being 0.2976.3)The phylogenetic tree analysis showed that the genetic distance relationship between Tibetan yak and domestic yak was the closest,the relationship followed were bison and European bison,and the farthest were buffalo and African buffalo,respectively.Taken together,the present results indicated that Tibetan yaks had abundant genetic diversity,which supports the theory that the Tibetan yak and domestic yak are independent of the genera bos that should be divided individually and the ancestor of the yak come from the northeastern part of the Eurasian continent.