中文摘要：

采用PCR—SSCP技术及mtDNA D-loop序列分析相结合的方法，对我国云南昭通绵羊、腾冲绵羊、宁蒗绵羊及西藏的多玛绵羊、江孜绵羊5个地方绵羊群体共232个个体进行遗传多样性及系统进化分析。PCR-SSCP分析显示，在西藏的多玛绵羊和江孜绵羊中均检测到线粒体编码区的Cytb和ND2基因的3种单倍型A、B和C，且在西藏的多玛绵羊、江孜绵羊中C单倍型比例高于B型；而在云南的昭通绵羊、腾冲绵羊和宁蒗绵羊中只检测到单倍型A和B。根据不同的单倍型从5个群体中筛选出39个样品进行mtDNAD-loop区克隆测序，经过系统进化分析揭示西藏绵羊存在A、B、C3种mtDNA单倍型；而云南绵羊只存在A、B2种mtDNA单倍型。以上基于PCR-SSCP和D-loop区序列的分析结果一致提示西藏绵羊有3个母系来源，云南绵羊有2个母系来源。基于mtDNAD-loop序列的多态性分析结果显示西藏多玛绵羊和江孜绵羊的单倍型多样度（Hd）、核苷酸多样度（Pi）及平均核苷酸差异数（k）均高于云南3个地方绵羊品种，提示西藏绵羊遗传多样性较丰富，云南绵羊遗传多样性相对贫乏。

英文摘要：

The genetic diversity and Phylogeny evolution of 232 individuals of 5 indigenous sheep populations in Southwest China was analyzed with PCR-SSCP technology and mtDNA D-loop sequenced. The five indigenous populations included Tengchong, Zhaotong, and Ninglang sheep from Yunnan and Duoma and Jiangzi sheep from Tibet. PCR-SSCP analyses revealed that three hyplotypes A, B, and C of mitochondrial Cyt b and ND2 genes were detected in Duoma and Jiangzi sheep from Tibet and the rate of hyplotypes C is higher than that of B;whereas only hyplotypes A and B found in Tengchong, Zhaotong, and Ninglang sheep from Yunnan. mtDNA D-loop sequences of 39 individuals chosen from the five according to different hyplotypes were sequenced. Phylogenetic analysis indicated that three mtDNA lineages A, B, and C were found in Tibetan sheep and only lineages A and B in Yunnan sheep. These results from PCR-SSCP and D-loop sequences consistently indicated that Tibet sheep derived from three maternal origins, While Yunnan sheep derived from two maternal origins. Polymorphism analyses showed that values of nucleotide diversity and average number of nucleotide differences in Tibetan sheep were higher than those of Yunnan sheep. This suggested that the level of genetic diversity in Tibetan sheep is higher than that in Yunnan sheep.