利用微卫星分析康西草原马匹种群的遗传多样性和群体结构

旨在揭示康西草原马匹的品种来源以及群体遗传结构。本研究采集了当地60匹健康状况良好、体重适中、3～6岁之间不区分公母马的血液样品,试验分为6个种群并以纯血马等4个国外马品种、1个我国地方马品种作为对照， 通过设计引物并提取基因组DNA结合微卫星扩增法对染色体上12个微卫星位点的等位基因进行检测，并对各种群遗传多样性参数、群体分化指数、瓶颈效应以及群体结构进行分析。试验按照群体个数为依据分为6组，每组1个重复，每个重复以该组样本量为标准。分析6个种群马的遗传参数结果表明，其中共检测到221个等位基因,平均Shannon指数为1.691；有效等位基因数(Ne)为3.649～5.397；期望杂合度(He)为0.681～0.798；观测杂合度(Ho)为0.632～0.780；平均多态信息含量(PIC)为0.643～0.772。这些结果表明，6个群体都具有很高的遗传多样性。通过微卫星DNA位点的连锁不平衡及哈迪-温伯格平衡分析发现， 大多数位点的P值都大于校正值(P=0.006 5)，表示较多位点都处于哈迪-温伯格及连锁平衡状态。各群体间群体分化系数(Fst)表明，群体间分化程度较低(Fst<0.15)。基于Nei’s遗传距离与地理距离之间Mantel相关性检验显示二者之间呈现正相关性(R=0.502)，但未达到显著水平(P=0.310)；各马匹种群瓶颈效应分析表明，P值极显著(P_(IAM)<0.01)说明该地区的马群体受到过瓶颈效应的影响且该马群体历史上数量有大规模的减少。通过 FCA因子分析、基于Nei’s标准遗传距离UPGMA树状图以及Structure贝叶斯聚类分析发现，该地区马种群与纯血马和温血马聚为一类，说明该种群最有可能主要来源于温血马和纯血马。这些结果揭示，康西草原地区马匹具有较高的遗传多样性，该地马群体的血统与纯血马和温血马相近，这为当地马遗传资源评估以及开发利用打下了坚实的基础。

Analysis of Genetic Diversity and Population Structure of Horse Population in Kangxi Grassland by Microsatellite DNA Markers

The purpose of this experiment was to reveal the variety source and population genetic structure of horse population in Kangxi grassland. The blood samples of 60 local horses with good health, moderate weight and indistinguishable male and female between the ages of 3 and 6 were collected. Four foreign horse breeds such as thoroughbred horses and one local horse breed in China were used as controls. The alleles of 12 microsatellite loci on chromosomes were detected by designing primers and extracting genomic DNA combined with PCR-STR. The genetic diversity parameters, population differentiation, bottleneck effect and population structure were analyzed. The experiment was divided into 6 groups according to the number of populations, with one repetition in each group. Each repetition was based on the sample size of this group. After analyzing the genetic parameters of 6 horse populations, the results showed that 221 alleles were detected, and the average Shannon index was 1.691; The number of effective alleles (Ne) ranged from 3.649 to 5.397; The expected heterozygosity (He) was 0.681-0.798; The observed heterozygosity (Ho) ranged from 0.632 to 0.780; The average polymorphism information content (PIC) ranged from 0.643 to 0.772. These results showed that the 6 populations had high genetic diversity. Microsatellite DNA locus linkage disequilibrium and Hardy-Weinberg equilibrium analysis showed that the P value of most loci was greater than the correction value (P>0.006 5), indicating that many loci were in Hardy-Weinberg and linkage equilibrium. The population differentiation coefficient (Fst) among populations showed that the degree of differentiation among populations was low (Fst<0.15). Based on the Mantel correlation test between Nei's genetic distance and geographical distance, there was a positive correlation between them (R=0.502), but it did not reach a significant level (P=0.310). The bottleneck effect analysis of horse populations showed that the horse populations in this area were affected by the bottleneck effect, and the P value was very significant (P_(IAM)<0.01), indicating a large-scale reduction in the number of the horse population in history. Through FCA factor analysis, UPGMA tree based on Nei's standard genetic distance and Structure Bayesian cluster analysis, it is found that the horse population in this area was clustered with thoroughbred horses and warm blood horses, indicating that the population was most likely to be mainly from warm blood horses and thoroughbred horses. These results reveal that horses in Kangxi grassland have high genetic diversity, and the lineage of the local horse population is similar to that of thoroughbred horses and warm blood horses, which lays a solid foundation for the evaluation, development and utilization of local horse genetic resources.