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【目的】了解人工选择偏好对奥利亚罗非鱼遗传多样性的影响,为今后人工选育及生产提供参考依据。【方法】对两个奥利亚罗非鱼群体(那马群体和武鸣群体)各70尾个体的线粒体DNA的D-loop区序列、Co I基因和Cytb基因进行测序及系统进化研究,并选用20对微卫星标记对其遗传多样性进行分析。【结果】基于D-loop区序列两个群体共检测出32个单倍型,其中共享单倍型6个;基于Co I基因共检测出23个单倍型,其中共享单倍型16个;基于Cytb基因共检测出14个单倍型,其中共享单倍型10个。基于D-loop区序列、Co I基因和Cytb基因单倍型分别构建的系统发育进化树显示,武鸣群体和那马群体的个体交错在一起,地理差异不明显,且采用NJ法和ME法构建系统发育进化树的进化拓扑结构基本相似。20对微卫星引物均能在奥利亚罗非鱼中获得稳定有效的扩增条带,其中有18个微卫星位点呈多态性;那马、武鸣群体的平均等位基因数(Na)分别为6.5000和7.9444,平均有效等位基因数(Ne)分别是3.9857和4.7268,平均观测杂合度(Ho)分别为0.7123和0.7752,平均期望杂合度(He)分别为0.9614和0.9711、平均Nei期望杂合度分别为0.7017和0.7636,均表现为武鸣群体略高于那马群体。两个群体的遗传分化系数(Fst)在不同微卫星位点间差异明显,其变化范围为0.0173(GM241)~0.2318(UNH868),平均0.0997;从单群体近交系数(Fis)和总群体近交系数(Fit)来看,所有微卫星位点的数值均为负值。【结论】经短期人工选择的武鸣群体奥利亚罗非鱼遗传多样性较被长期人工选择的那马群体遗传多样性丰富,即短期内的不同人工选择偏好对线粒体DNA的遗传影响较小。
【Objective】 The purpose of this study was to understand the influence of artificial selection preference on the genetic diversity of O. tilapia and to provide a reference for future artificial breeding and production. 【Method】 The D-loop region, Co I gene and Cytb gene of mitochondrial DNA from 70 individuals of two populations of Tilia niloticus (Nama population and Wuming population) were sequenced and phylogenetically analyzed. Twenty pairs of microsatellite markers were used to analyze their genetic diversity. 【Result】 Twenty-two haplotypes were detected in the two populations based on the D-loop region sequence, of which six haplotypes were shared. Twenty-three haplotypes were detected based on the Co I gene, of which 16 shared haplotypes. A total of 14 haplotypes were detected based on the Cytb gene, of which 10 shared haplotypes. The phylogenetic tree constructed based on the D-loop region sequence, Co I gene and Cytb haplotype respectively showed that the individuals of Wuming population and that of Nima population were staggered together with no obvious geographical difference. The NJ and ME methods The evolutionary topologies of phylogenetic tree are basically similar. 20 pairs of microsatellite primers could obtain stable and effective amplification bands in O. aurea, of which 18 microsatellite loci were polymorphic; the average number of alleles Na were 6.5000 and 7.9444, respectively. The average number of effective alleles (Ne) was 3.9857 and 4.7268 respectively. The average observed heterozygosity (Ho) was 0.7123 and 0.7752 respectively. The average expected heterozygosity (He) was 0.9614 and 0.9711 respectively. The expected heterozygosity for Nei was 0.7017 and 0.7636, respectively, both of which were slightly higher than that of the WuMa population. The genetic differentiation coefficient (Fst) of two populations differed significantly among different microsatellite loci, ranging from 0.0173 (GM241) to 0.2318 (UNH868) with an average of 0.0997. From the single population inbreeding coefficient (Fis) and the total population For the Fit, all microsatellite loci have negative values. 【Conclusion】 The results showed that the genetic diversity of O. tilapia from the short-term artificial selection was more abundant than that from the long-term artificial selection. That is, the short-term genetic preferences of different artificial selection preferences for mitochondrial DNA were smaller .