牦牛是青藏高原的"当家畜种"，与藏民族的生活息息相关。目前，牦牛的遗传多样性及起源研究仍然是牦牛科学研究中的热点问题，但基于父系遗传角度（即Y染色体）对该问题的研究相对较少。本项目以中国12个牦牛品种（包括11个地方品种和1个培育品种）为研究对象，利用PCR、STR荧光分型、TA克隆测序及生物信息学方法和技术，设计新的Y-STR和Y-SNP标记引物，选择遗传差异较大的牦牛品种制成DNA池，筛选出新的Y染色体多态标记，再结合前人已探明的3个牦牛特异Y-STR多态标记（即INRA124、INRA189和BYM-1），系统地分析中国牦牛品种的Y-STR、Y-SNP多态性，探究其Y染色体单倍型、遗传多样性、分子系统地理学与分子进化特征，揭示中国牦牛的父系遗传多样性水平、父系起源、可能的驯化中心及迁徙路线等问题。研究将为整体评估中国牦牛的遗传资源状况、开展品种培育和杂交优势利用等实践奠定理论基础。

Yak is an important livestock living on the Qinghai-Tibet plateau and its adjacent territories.It is closely related to the life of Tibetan.At present,the genetic diversity and origin of yak is still the hotspot problem in yak science.But to the problem of paternal genetic diversity and origin of yak, little is known.In view of this, the 420 male individuals from 12 Chinese yak breeds (i.e.Jiulong yak,Maiwa yak,Tibetan alpine yak,Sibu yak,Pali yak,Qinghai platean yak,Qinghai huanhu yak,Tianzhu white yak, Gannan yak,Bazhou yak,Zhongdian yak and Datong yak) will be analyzed in this project based on the methods and techniques from PCR,STR fluorescent genotype,TA cloning and sequencing, and bioinformatics so as to explore the paternal genetic diversity and origin of Chinese yaks. We will design the new Y-STR and Y-SNP primers and single out the yak breeds that have the largger genetic difference each other for making the DNA pool, and then screen out the new polymorphic Y-chromosome-specific markers. Combined with the three previous polymorphic Y-STR markers(i.e.INRA124,INRA189 and BYM-1), we will analyze systematically the polymorphism of Y-STR and Y-SNP markers in Chinese yaks and explore the haplotypes, genetic diversity, molecular phylogeography and evolution of the Y chromosome.The aim is to indicate the levels and differences of paternal genetic diversity among and between 12 yak breeds and explore the yak's origin,possible demestication center and migration routes.The study will offer an overall assessment to Chinese yak genetic resources and provide the theoretical basis for further exploring the level of paternal genetic diversity,origin and domestication of yaks in the world and using the hybrid vigor in yak.