我国蒙古羊系统不同生态型绵羊品种遗传多样性及距离隔离机制的研究

以我国主要地方绵羊品种湖羊、同羊、小尾寒羊、滩羊和洼地绵羊为研究对象,检测位于不同染色体的微卫星位点的基因频率分布,进行比较分析.结果表明 1) 就本研究涉及的微卫星标记而言,湖羊处于Hardy-Weinberg极不平衡状态 (P ＜ 0.01),而其余群体包括同羊、小尾寒羊、滩羊和洼地绵羊却处于Hardy-Weinberg平衡 (P ＜ 0.05).2) 就本研究涉及的微卫星标记而言,平均杂合度、多型信息含量和有效等位基因数三个遗传变异指标的方差分析表明不同群体间杂合度、多型信息含量均不存在显著差异 (P ＞ 0.05),有效等位基因数遗传变异指标在、滩羊、湖羊、同羊和洼地羊相互之间以及洼地羊与小尾寒羊之间亦差异不显著(P ＞ 0.05),但是有效等位基因数在前3个群体与后2个群体之间存在显著差异 (0.01 ＜ P ＜ 0.05).5个绵羊群体的变异水平以小尾寒羊最高,其次为洼地绵羊、同羊和滩羊,最低的是湖羊.3) 本研究涉及的我国蒙古羊系统内5个绵羊群体间的系统发生关系不满足距离隔离模式,绵羊群体间的遗传分化关系的远近与其地理分布并未表现出紧密的线性相关.这与5个绵羊起源于不同时期的蒙古羊始祖群体,同时在品种间存在一定程度的基因交流,并在各自特有的生态环境中经历不同程度的自然选择和人为选择品种培育史实相符.

Analysis on Genetic Diversity and Isolation Mechanism by Distance of Different Ecological Type Sheep Breeds in Mongolia Sheep Group

In the present study with Tan sheep,small-tailed Han sheep,Hu sheep,Tong sheep,and Wadi sheep,we detected the distribution of gene frequency of several microsatellite sites in different chromosomes,the result showed that: 1) Hu sheep was in the status of Hardy-Weinberg extreme disequilibrium (P < 0.01),while populations including Tong sheep,small-tailed Han sheep,Tan sheep,and Wadi sheep were in Hardy-Weinberg equilibrium (P > 0.05). 2) Variance analysis of the heterozygosity and poly-morphic information content at microsatellite makers showed that there were not significant differences among populations as to heterozygosity and PIC (P > 0.05),as to effective number of alleles there were not significant differences both among Tan sheep,Hu sheep,Tong sheep,and Wadi sheep,and between Wadi sheep and small-tailed sheep (P > 0.05),but between the former three populations and the latter two populations,there were significant differences (0.01< P < 0.05). The variation levels of small-tailed Han sheep was the highest in the five populations based on microsatellite maker data,subsequently followed by Wadi sheep,Tong sheep,Tan sheep,and then Hu sheep. 3) The phylogenetic relationships of the five sheep populations in this study did not meet the mechanism of isolation by distance,and the genetic differentiation relationships among five sheep populations were not closely linearly correlative with their geography distribution. Our findings supported related records in literature:The five populations originated on different time stage from the primogenitor population and communicated genetically with each other thereafter in the process of natural and artificial selection and on different ecological environment.