摘要：

旨在通过mtDNA ND1探究6个西藏特色牦牛群体的遗传多样性、系统进化及亲缘关系,为西藏牦牛的遗传多样性、历史演化以及遗传资源保护与利用等提供理论依据。利用PCR和直接测序法分别测定了西藏帕里牦牛、嘉黎牦牛、工布江达牦牛、斯布牦牛、江达牦牛、类乌齐牦牛6个群体共95头个体ND1基因蛋白质编码区(CDS)序列,利用DNAMAN、DNASP 5.1、Mega 7.0、Arlequin 3.5.2等软件分析其序列多态性、单倍型多样性、遗传距离等,并构建单倍型网络图及系统发育树。结果表明,西藏牦牛群体ND1基因CDS区序列长度均为956 bp,共检测获得78个变异位点和16种单倍型,平均单倍型多样性(Hd)及核苷酸多样性(Pi)分别为0.670和0.004 21,Tajima's D均为负值;根据群体遗传差异的分子方差分析可知,西藏牦牛群体内的变异程度大于群体间变异;斯布牦牛与嘉黎牦牛之间的分化程度较大,其余大部分群体间的分化程度为中等或较弱。此外,通过聚类分析发现,类乌齐牦牛单独聚为一类,而嘉黎牦牛、工布江达牦牛、斯布牦牛、江达牦牛先聚为一类,然后再与帕里牦牛聚为一大类;16种单倍型可分为2个聚类簇,说明西藏牦牛可能存在2个母系起源;与其他牛种进行聚类分析,发现家牦牛、爪哇野牛和普通牛可能是西藏牦牛的混合母系起源。西藏牦牛遗传多样性十分丰富,其中类乌齐牦牛遗传多样性最丰富,6个牦牛群体存在2个母系起源。

关键词: 西藏牦牛, ND1基因, 遗传多样性, 系统进化, 遗传分化

Abstract:

The aims of this study were to explore the genetic diversity,phylogenetic evolution and genetic relationship from six yak groups of Tibetan yaks by mtDNA ND1.To provide a theoretical basis for the genetic diversity,historical evolution,the protection and utilization of genetic resources of Tibetan yaks.The sequences of ND1 gene protein coding region(CDS)in 95 individuals of Pali yak,Jiali yak,Gongbujiangda yak,Sibu yak,Jiangda yak and Leiwuqi yak were analyzed by PCR and direct sequencing.DNAMAN,DNASP 5.1,Mega 7.0,Arlequin 3.5.2 and other software were used to analyze the sequence polymorphism,haplotype diversity,genetic distance and constructed the haplotype network map and phylogenetic tree.The result showed that the sequence length of CDS region of ND1 gene of Tibetan yaks population were 956 bp,and a total of 78 mutation loci and 16 haplotypes were detected and the average haplotype diversity(Hd)and nucleotide diversity(Pi)were 0.670 and 0.004 21,Tajima's D was all negative.According to the molecular variance analysis of population genetic differences,the degree of variation within Tibetan yaks was greater than among populations;the degree of differentiation between Sibu yak and Jiali yak was large,and the degree of differentiation among most other groups was medium or weak.In addition,cluster analysis found that Leiwuqi yak was grouped into a single group,Jiali yak,Gongbujiangda yak,Sibu yak and Jiangda yak were first grouped into one group,and then grouped with Pali yak;the 16 haplotypes were divided into two clusters,suggesting that there may be two maternal origins in Tibetan yaks.The cluster analysis with other cattle breeds showed that Bos grunniens,Bos taurus and Bos javanicus may be the mixed maternal origin of Tibetan yaks.The genetic diversity of Tibetan yaks was very rich,among which the genetic diversity of Leiwuqi yaks was the most abundant,six yak populations had two maternal origins.

Key words: Tibetan yak, ND1 gene, Genetic diversity, System evolution, Genetic differentiation