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作 者 ：郭松长,祁得林,陈桂华,徐世晓,赵新全*

期 刊 ：生态学报 2008年 28卷 9期 页码：4286~4294

关键词：家牦牛；mtDNA控制区；遗传多样性；聚类关系；遗传分化；分类；

Keywords:domestic yaks, mtDNA D-loop, genetic diversity, clustering relationship, genetic differentiation, classification,

摘 要 ：通过分析包括我国10个家牦牛品种（类群）在内共296个样本的mtDNA控制（D-loop）区部分序列的遗传变异，对我国家牦牛的遗传多样性、遗传分化、聚类关系和分类进行了研究。所测序列经比对后，共检测到61个变异位点，定义了77种单倍型。分析显示青海环湖牦牛的单倍型多样性最高，达0.9848±0.0403，而巴州牦牛单倍型多样性最低，为0.8000±0.0825；核苷酸多样性方面，斯布牦牛存在最为丰富的核苷酸序列变异，核苷酸多样性值为0.022582±0.011767，而巴州牦牛仅为0006856±0.002476，表明我国家牦牛品种（类群）遗传多样性水平存在较大差异。总体上，我国家牦牛单倍型多样性、核苷酸多样性分别为0.9251±0.0095和0.015265±0.007757，呈现出丰富的遗传多样性。聚类分析显示我国家牦牛存在两个聚类簇——斯布牦牛独立为一类；其余9个品种（类群）聚为一类，表明家牦牛品种（类群）间遗传距离与地理分布无明显相关。分子变异分析（AMOVA）显示九龙、嘉黎、斯布牦牛构成的组与其余7个家牦牛品种（类群）构成的组之间存在极显著的遗传分化（ΦCT=005285，P<0.01），且其品种间/组内遗传分化不显著（ΦSC=0.00648，P>0.05），支持依据遗传分化程度将我国家牦牛划分为两大类型。AMOVA支持的分组在品种（类群）组成上与蔡立的研究结果相符，首次为我国家牦牛划分为横断高山型和青藏高原型两种类型提供了源自分子遗传学的证据。

Abstract:To investigate the genetic diversity, clustering relationship, genetic differentiation and classification, we presented molecular variation analysis of partial mitochondrial(mt) DNA D-loop from 296 individuals encompassing 10 yak breeds. The aligned 637 bp fragments included 61 variable sites, and a total of 77 haplotypes were identified. The genetic diversity analysis demonstrated that there was significant difference between breeds of domestic yaks. Among 10 yak breeds, Huanhu yak and Bazhou yak showed the highest and the lowest haplotype diverisity (0.9848±0.0403 and 0.8000±00825), respectively. Where as for the nucleotide diversity, Sibu yak and Bazhou yak presented the highest and the lowest values (0.022582±0.011767 and 0.006856±0.002476), respectively. In all domestic yaks, a high genetic diversity was observed with 0.9251±0.0095 for haplotype diversity and 0.015265±0.007757 for nucleotide diversity. The clustering relationship indicated that 10 yak breeds could be divided into two clades. The first clade included only Sibu yak, and the second clade consisted of the remaining 9 breeds. The result showed that there is no significant correlation between genetic distance and geographic distribution in yak breeds. Analysis of molecular variance (AMOVA) revealed remarkably significant genetic differentiation (ΦCT=0.05285, P<0.01) between Jiulong-Sibu-Jiali group and multi-breeds group. However, no significant genetic differentiation was detected among breeds within groups (ΦSC= 0.00648, P>0.05). These data suggested that 10 yak breeds should be classified into two types. Our result accorded with previous study conducted by Professor Caili, and provided direct genetic evidence for reasonable classification of domestic yak breeds.

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