两个人工选择奥利亚罗非鱼群体系统发育及其遗传多样性分析

【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。

Phylogeny and genetic diversity of two artificial selection Oreochromis aureus populations

Objective]Influences of artificial selection preference on Oreochromis aureus genetic diversity were studied to provide some reference for O. aureus breeding and production. Method]Sequence and phylogeny of mitochondrion DNA D-loop region, Cytb gene and COI gene from 140 individuals of two O. aureus populations(70 from Nama population and 70 from Wuming population) were studied. Meanwhile, 20 pairs of microsatellite primers were applied to analyze the genetic diversity. Result]Thirty haplotypes were detected based on D-loop region and six of them were shared haplotypes; twen-ty-three were detected based on CoI gene and sixteen were shared haplotypes; fourteen were detected based on Cytb gene and ten were shared haplotypes. Phylogenetic trees based on D-loop region sequence, CoI gene and Cytb gene indicated that the individuals from Wuming population and Nama population interveined and showed no obvious geographical difference . Evolution topology of phylogenetic trees based on Neighbor-joining ( NJ ) method and Minimum-evolution (ME)method were similar. All 20 pairs of microsatellite primers could obtain stable and effective amplified bands from O. aureus, and 18 microsatellite loci presented polymorphism . Average allele numbers (Ne) for Nama population and Wuming population were 6.5000 and 7.9444 respectively, average effective allele numbers(Ne) were 3.9857 and 4.7268, average observed heterozygosity (Ho) were 0.7123 and 0.7752, average expected heterozygosity (He) were 0.9614 and 0.9711, average Nei expected heterozygosity were 0.7017 and 0.7636. All the indexes for Wuming population were higher than those of Nama population. There was obvious difference of coefficient of genetic differentiation (Fst) at different mi-crosatellite loci, ranging from 0.0173(GM241)-0.2318(UNH868) with an average of 0.0997. From the perspective of inbreeding coefficient of single group(Fis) and inbreeding coefficient of total groups(Fit), the values of all microsatellite loci were negative. Conclusion]Genetic diversity of Wuming population which was artificially selected for short term is more abundant than that of Nama population which was artificially selected for long time. In another words , influence of artificial selection on mitochondria DNA is small in short term.