西藏阿里地区牦牛生态类群分子遗传多样性研究

Molecular Genetic-Diversity Estimation of Yak Ecological Population in Ali of Tibet

利用多种分子标记鉴定西藏阿里牦牛生态类群遗传多样性状态,以期为阿里牦牛遗传资源的保护、开发和利用奠定理论基础。利用13个微卫星标记位点及线粒体D-Loop高变区分别对69头和50头西藏阿里牦牛进行了遗传多样性评估。结果显示,在13个微卫星位点中共检测出124个等位基因,其中TGL122和ILSTSO50位点的复等位基因数最多(15个),BGR3001位点的等位基因数最少(1个);从群体上来看,阿里牦牛群体的平均观测杂合度(Ho±SD)为0.5790±0.0139,其中11个位点偏离哈代-温伯格平衡,且近交系数(FIS)为0.192(P<0.05);虽然依据IAM和TPM模型暗示该群体存在显著瓶颈效应(P<0.05),但模式迁移图形仍为L-型分布;阿里牦牛线粒体D-loop区序列的794 bp片段范围内,共计鉴定到80个变异位点,同时构建得到38个单倍型,全部单倍型分为2个母系支系;群体平均单倍型多样性(Hd)为0.941,平均核苷酸多样性(Pi)为0.01600。说明目前阿里牦牛群体内仍具有较丰富的母系遗传多样性,但群体整体可能存在近交和经历瓶颈效应的风险,故而需要进一步加强该群体保种工作,同时优化或改变现有保种模式和方案。

This study was to identify the genetic-diversity status of a Tibet Ali yak ecological population in order to lay a theoretical foundation for the protection using multiple molecular markers,development and utilization of Ali yak genetic resources.Total 13 microsatellite markers and mitochondrial D-Loop hypervariable region were genotyped for 69 and 50 Ali yak individuals,respectively,to evaluate the genetic diversity.The results showed that total 124 alleles were detected in 13 loci,among which TGL122 and ILSTSO50 had the most number of alleles(15),BGR3001 had the least(1),and all individuals were homozygous.From the perspective of population,the average observed heterozygosity(Ho±SD)of the Ali yak population was 0.5790±0.0139,11 of which significantly deviated from the Hardy-Weinberg equilibrium.The inbreeding coefficient(FIS)and the population might be under a significant bottleneck effect(P<0.05),as indicated by the IAM and TPM model,but the pattern transfer pattern was still an L-shaped distribution.Secondly,analysis results of the mtDNA D-Loop region of 50 Ali yak individuals showed that a total of 80 mutation sites were found and 38 haplotypes were constructed within the 794 bp fragment of the mitochondrial D-loop region of Ali yak,as well as all 38 haplotypes were divided into two matrilineal branches.The population average haplotype diversity(Hd)was 0.941,and the average nucleotide diversity(Pi)was 0.01600.In short,the current Ali yak population had rich maternal genetic diversity but still had the risk of inbreeding and experiencing bottleneck effects.Therefore,population-conservation work requires increased strengthening and optimized.