【作者】 鲁生霞；

【导师】 常洪；

【作者基本信息】 扬州大学 ， 动物遗传育种与繁殖， 2004， 硕士

【摘要】 采用中心产区典型群随机抽样方法和多种电泳技术检测60只小尾寒羊、73只滩羊编码血液蛋白17个结构基因座上的变异，引用国内外14个绵羊群体相同资料进行比较分析，探讨其遗传分化关系。研究表明：(1)小尾寒羊、滩羊结构基因座平均杂合度分别为0.2360和0.2587：平均多态信息含量分别为0.1974、0.2102；平均有效等位基因数分别为1.5723和1.5751。(2)4个组合(分别为4个、6个、13个及16个绵羊群体)的基因分化系数分别为0.049323、0.059987、0.1728和0.201256，说明湖羊、同羊、小尾寒羊和滩羊4个绵羊群体结构基因座的基因分化程度低；这4种绵羊与蒙古羊群体间基因分化程度次之；蒙古羊系绵羊和南亚羊及欧洲羊之间遗传分化程度较高。(3)前人关于小尾寒羊、滩羊由蒙古羊分化而来的考证得到遗传学实验的进一步证明，湖羊、同羊、小尾寒羊和滩羊受蒙古羊血统的影响递减。群体间亲缘关系远近与其所处地理位置远近并未表现出紧密相关。 以小尾寒羊、滩羊为材料，检测7个微卫星位点的遗传多态性，并引用湖羊、同羊及长江三角洲白山羊(参照群体)相同资料进行群体遗传分化水平分析。研究表明：(1)小尾寒羊、滩羊7个微卫星位点平均杂合度分别为0.9336和0.9116；多态信息含量与杂合度平行变化：平均有效等位基因数分别为16.4532和11.6884，表明小尾寒羊在非编码区的遗传变异程度高于滩羊。(2)4个绵羊群体7个微卫星位点基因分化系数为0.026329，绵山羊群体则为0.039036，表明绵羊群体间及绵山羊群体间基因分化程度较低。(3)7个微卫星标记分析表明湖羊和同羊、滩羊和小尾寒羊亲缘关系较近，后者关系需要进一步研究。(4)相对进化距离(RED)可定义为:1与同物种群体间模糊聚类置信水平值(入n)的差值和1与近缘物种参考群体、同物种总群体模糊聚类置信水平值(人)的差值之比值。湖羊和同羊的相对进化距离为0.253:小尾寒羊和滩羊的相对进化距离为0.407;湖羊、同羊和小尾寒羊、滩羊的相对进化距离为0.462。 以中心产区典型群随机抽样方法获得的小尾寒羊、滩羊、湖羊与同羊13个结构基因座、7个微卫星位点基因频率分布为研究对象，进行比较分析，尝试探讨群体间遗传分化关系。结果表明:(l)微卫星各位点的杂合度、多态信息含量、有效等位基因数及其平均值均高于结构基因座的相应指标，微卫星标记揭示的群体变异水平较高:基于微卫星标记的群体间标准遗传距离高于结构基因座的相应值;微曰己位点雄因频率资料计算的总位点基因分化系数低于结构基因座的相应指标，1洋体间基因分化水平总体上较低;两层次基因频率模糊聚类分析揭示的群体间关系不完全一致，相异之处有待进一步验证。(2)结构基因座和微卫星位点两层次基因频率资料的综合分析得出的结果没有与既有研究报道、文献一记载及本研究单层次基因频率资料分析相吻合，需要进一步深入研究探讨。更多还原

【Abstract】 Using the method of " random sampling in typical colonies of the central area of the habitat " and several electrophoresis techniques, the variations of 17 structural loci encoding blood proteins in 60 Small Tailed Han sheep and 73 Tan sheep were examined and compared with those of 14 other sheep populations in China and other countries to explore their relations of genetic differentiation. The average heterozygosities (h) of Small Tailed Han sheep and Tan sheep were 0.2360 and 0.2587, respectively. Their average polymorphic information contents (PIC) were separately 0.1974 and 0.2102. Their average effective number of alleles (Ne) valued 1.5723 and 1.5751 each. The coefficients of gene differentiation of four groups (including 4, 6, 13, 16 sheep populations, respectively) were 0.049323, 0.059987, 0.1728 and 0.201256, respectively, which indicated that the level of gene differentiation at the structural loci among Hu sheep, Tong sheep, Small Tailed Han sheep and Tan sheep was low, the level of gene differentiation among above-mentioned four sheep populations and Mongolian sheep higher, and the level of gene differentiation among sheep belonging to Mongolian sheep group, South Asian sheep and European sheep highest. Earlier researchers proposed that Small Tailed Han sheep and Tan sheep both evolved from Mongolian sheep, the proposition was further verified by the results in this study. Hu sheep, Tong sheep, Small Tailed Han sheep and Tan sheep were decreasingly affected by the bloodline of Mongolian sheep. The relationships between sheep populations were not closely related to the distances between sheep populations.Using seven microsatellite markers, we examined the genetic variations of Small Tailed Han sheep and Tan sheep and estimated their gene frequencies. The same data of Hu sheep, Tong sheep and Yangtse River Delta White goat, which served as the referenced population, were cited to further explore their levels of genetic differentiation. The mean heterozygosities of Small Tailed Han sheep and Tan sheep were 0.9336 and 0.9116, respectively. The polymorphic information content values were parallel to the heterozygosities. The mean effective number of alleles valued 16.4532 and 11.6884, respectively. The values of these three parameters showed the degree of genetic variation in Small Tailed Han sheep in non-coding regions was higher than that in Tan sheep. The coefficient of gene differentiation among four sheep populations was 0.026329, and that among sheep and goat populations was 0.039036, indicating that the degree of gene differentiation was comparatively low among sheep populations and that among sheep and goat populations higher. The relationships of the pair Hu-Tong sheep and Small Tailed Han-Tan sheep were both close. The latter, however, needed further verification. Further, we calculated the relative evolution distance (RED) of the above sheep populations. RED is defined as a ratio of the converse of the confidence level value( n) of the fuzzy cluster among the infraspecific populations to the converse of the least confidence level value( ) among a referenced population of closely related species and all the infraspecific populations. RED between Hu sheep and Tong sheep was 0.253, that between Small Tailed Han sheep and Tan sheep 0.407, and that between Hu sheep-Tong sheep and Small Tailed Han sheep-Tan sheep 0.462.The gene frequencies of 13 structural loci and 7 microsatellite loci in Small Tailed Han sheep, Tan sheep, Hu sheep and Tong sheep, which were sampled by the method " random sampling in typical colonies of the central area of the habitat ", were comparatively analyzed and discussed to verify the relationships of genetic differentiation among populations. The results showed the heterozygosity, polymorphicinformation content, effective number of alleles at each microsatellite locus and their average were higher than those at each structural locus, which indicated that the levels of population variations revealed by the microsatellite loci were higher than those by the structural l更多还原