西藏牦牛mtDNA ND5遗传多样性及系统进化分析

Genetic Diversity and Phylogenetic Analysis of mtDNA ND5 of Tibetan Yaks

为了解西藏牦牛的遗传多样性和群体分化情况,本研究测定了西藏15个牦牛类群的mtDNA ND5基因序列,分析其遗传多样性、亲缘关系及分类。结果表明：①西藏牦牛mtDNA ND5全序列长度在1821～1823 bp,无内含子,T、C、A和G 4种碱基的平均比例分别为32.9%、10.6%、27.5%、29.0%,存在一定的碱基组成偏倚性。②共发现变异位点36个,其中15个单态突变位点,13个简约信息位点;存在碱基缺失、插入、转换和颠换等,插入或缺失位点8个,T/C转换较多,G/C颠换较少。③西藏牦牛mtDNA ND5共有23种单倍型,平均单倍型数（H）、平均单倍型多样性（Hd）、平均核苷酸多样性（Pi）分别为3.4667、0.5100和0.00102,表明西藏牦牛具有丰富的遗传多样性。④西藏牦牛mtDNA ND5基因共含20种氨基酸,其中缬氨酸最多,占10.37%,组氨酸最少,仅为1.11%。⑤在西藏牦牛的聚类分析中,仲巴牦牛、桑桑牦牛、斯布牦牛、错那牦牛、日多牦牛、嘉里牦牛、工布江达牦牛、康布牦牛、江达牦牛、桑日牦牛、丁青牦牛、聂荣牦牛、帕里牦牛首先聚为一大类,再依次与隆子牦牛和类乌齐牦牛相聚。

The mtDNA ND5 gene of yak groups from Tibet was sequenced to study the genetic diversity,genetic relationship and classification. The results showed that,（ i） The whole sequence length in Tibet yak was from 1821 to 1823 bp and no introns,the average proportion of these four bases（ T,C,A and G） were 32. 9 %,10. 6 %,27. 5 % and 10. 6 % and there was a certain base composition bias.（ ii） The total 36 variation locis were found,including in 15 singleton mutations and 13 simple information site. There were base deletion,insertion,transition and transversion,etc,8 insertions or deletions loci; T / C transformation was more and less in G / C transversion.（ iii） There were 23 type single times in Tibet yak mtDNA ND5. The average number of haploid type（ H）,average haploid type diversity（ Hd）,average nucleotide diversity（ Pi） were 3. 4667,0. 5100 and 0. 00102. It showed that Tibet yak had abundant genetic diversity.（ iv） There were 20 kinds of amino acids in Tibet yak mtDNA ND5 gene. The Valine was the largest,accounted for 10. 37 % and the Histidine was the least,only 1.11 %. Clustering analysis showed that ZB,SS,SB,CN,RD,JL,GB,KB,JD,SR,DQ,NR and PL were clustered into a group,and this branch was togethered with LZ and LWQ in Tibet yak.