青海湖裸鲤线粒体DNA D-loop区的遗传多样性及其遗传分化研究

为了科学有效地保护青海湖裸鲤的种质资源,对青海湖裸鲤的遗传多样性及种群结构进行研究是尤为重要。本研究采用PCR技术对青海湖裸鲤的4个种群（青海湖、可鲁克湖、甘子河、草搭连）155个个体的mtDNA D-loop区部分序列进行扩增,得到了754 bp的核苷酸序列。采用MEGA 5.05和DnaSP 5.10.1软件对序列进行分析,结果显示：155个个体中共检测出34个单倍型,单倍型多样性（Hd）为0.906±0.013,核苷酸多样性（Pi）为0.00556±0.00034。其中可鲁克湖种群的单倍型多样性0.422±0.093和核苷酸多样性0.00272±0.00066均低于其他3个种群,且该种群内的平均遗传距离（0.00276）低于群体间的遗传距离0.00522~0.00709。通过群体分化指数（Fst）和基因流（Nm）分析显示,可鲁克湖种群与其他3个种群之间有着明显的遗传分化（Fst〉0.26327,Nm〈0.69959）,且与甘子河种群分化程度最显著（Fst=0.45854,P〈0.01;Nm=0.29521）。但是系统发育树并未显示出明显的单系群,可能是水系间地理隔离格局的形成时间较晚。研究结果表明：青海湖裸鲤具有较高的遗传多样性,种群间出现了一定程度的遗传分化,特别是可鲁克湖种群已经高度分化,但其遗传多样性水平很低,应优先对其进行保护。

Genetic Diversity and Differentiation of Mitochondrial DNA D-loop Region in Gymnocypris przewalskii

In order to protect germplasm resources of Gymnocypris przewalskii scientifically and effectively, it was especially important to investigate the population structure and genetic polymorphisms of Gymnocypris przewalskii. 754 bp nucleotide sequences of mtDNA D-loop region were obtained from 155 individuals of four populations (Lake Qinghai, Lake Keluke, Ganzi River and Cao Dalian) by PCR amplification. The sequences were analyzed by using the MEGA (version 5.05) and DnaSP (version 5.10.1) software. The results showed that 34 haplotypes were detected among 155 individuals. The haplotype diversity (Hd) and the nucleotide diversity (Pi) were (0.906±0.013) and (0.00556±0.00034) respectively. The haplotype diversity and nucleotide diversity of Lake Keluke population were (0.422±0.093) and (0.00272±0.00066), which were lower than those of three other populations. The low level of gene flow (Nm<0.69959) and high population differentiation values (Fst>0.26327) between Keluke population and other populations showed considerable genetic isolation, while the highest genetic differentiation was detected between Lake Keluke population and Ganzi River population (Fst=0.45854, P<0.01; Nm=0.29521). But no monophyletic group was observed clearly in the phylogenetic tree. This may be the geographic barriers among the drainages were formed relatively late. It could be concluded that Gymnocypris przewalskii has high genetic diversity. It was a certain degree of differentiation among Gymnocypris przewalskii in different geographical populations, especially Lake Keluke population. But the genetic diversity of Lake Keluke population was low, so we should make it a priority to protect.