西藏牦牛mtDNA D-loop区的遗传多样性及其遗传分化  

Genetic diversity and evolution relationship on mtDNA D-loop in Tibetan yaks

作　　者：张成福[1] 徐利娟[2] 姬秋梅[1] 信金伟[1] 钟金城[2] 

机构地区：[1]西藏自治区农牧科学院畜牧兽医研究所,拉萨850000 [2]动物遗传育种学国家民委-教育部重点实验室,西南民族大学,成都610041

出　　处：《生态学报》2012年第5期1387-1395,共9页Acta Ecologica Sinica

基　　金：西藏自治区重点科研项目计划资助(20092-1)

摘　　要：通过测定和分析西藏11个牦牛类群114个个体的mtDNA D-loop区全序列,对西藏牦牛的遗传多样性、类群间的亲缘关系及其遗传分化进行了研究。结果表明:①西藏牦牛mtDNA D-loop区全序列长度为890—896 bp,4种核苷酸T、C、A、G的平均比例分别为28.5%、25.3%、32.4%、13.8%,西藏牦牛mtDNA D-loop区富含碱基A+T,表现出一定的碱基偏好性。②共检测到130个变异位点,占分析总位点数的14.33%;其中单一多态位点85个,占多态位点总数的65.38%,简约信息位点45个,占多态位点总数的34.62%。序列变异中碱基缺失、插入和碱基替换等均有,其中碱基替换变异类型中转换114次,颠换12次,在转换变异类型中以A/G、T/C为主,占95.61%,在颠换变异类型中以A/T为主,占75%。③在114个个体中鉴定出90种单倍型,单倍型多样性为0.981±0.008,核苷酸多样性为0.01056±0.00701,均说明西藏牦牛具有丰富的单倍型类型。④90种单倍型分为2个聚类簇(Ⅰ、Ⅱ),聚类簇Ⅰ包含80种单倍型,占全部单倍型的88.89%,涵盖本研究中所有的西藏牦牛类群;聚类簇Ⅱ中有10种单倍型,占单倍型总数的11.11%,涉及的类群有工布江达、帕里、丁青、巴青、江达、类乌齐、桑桑、桑日、斯布,说明西藏牦牛可能有2个母系起源。⑤西藏牦牛类群间核苷酸分歧度(Dxy)在0.503%—1.416%之间,聚类分析和AMOVA分析显示西藏牦牛可分为两大类,康布牦牛、嘉黎牦牛为一类,其余的牦牛类群为另一类。To investigate the genetic diversity, clustering relationships and genetic differentiation of Tibetan yak （Bos grunniens） populations, we analyzed the complete sequence of the mitochondrial DNA control region （D-loop） of 114 individuals from 11 yak populations. To clarify the origin, phylogeny and taxonomic position of B. grunniens, we retrieved a further 48 D-loop sequences from five diverse populations of B.runniens, resulting in 162 sequences from 16 populations in total. Results showed some nucleotide bias in the 890-896bp bp Tibetan yak mtDNA D-loop sequence, with nucleotide frequencies of 28.5%, 25.3%, 32.4% and 13.8% for T, C, A and G respectively. A total of 90 haplotypes were identified, with 130 polymorphic sites （14.33% of total analyzed sites）. Of these, 45 sites represented single nucleotide polymorphisms; while a further 85 sites were parsimony-informative. The population haplotype diversity ranged from 0.93-1.00 with an average of 0.98±0.008, indicating a high level of genetic diversity within Tibetan yak populations. The majority of polymorphisms were A/G and T/C transitions or A/T transversions. Polymorphisms were more frequent in the Sangri yak and Baqing yak populations, and occurred less frequently in the Kangbu yak and Jiali yak populations. The 90 haplotypes were divided into two clusters by constructing a network relationship chart. This result suggests that Tibetan yaks may be derived from two separate maternal lineages. The degree of nucleotide difference among the 11 populations ranged from 0.503%-1.416%. The Sangri and Baqing populations had the highest degree of difference, whereas the lowest difference was observed between the Kangbu and Jiali populations. Because of this data, we suggest an apparent genetic differentiation between the Sangri and Baqing populations. Tajima＇s test of selective neutrality was significant （0.01 〈 P〈0.05） for the Leiwuqi yak, Dingqing yak, Jiangda yak, and Gongbujiangda yak populations, but not significant （P 〉 0.05） for other

关 键 词：西藏牦牛 MTDNA D-LOOP区 遗传多样性 

分 类 号：S823[农业科学—畜牧学]