长江上游长鳍吻鮈群体线粒体控制区遗传多样性分析

分析长鳍吻鮈群体遗传结构和遗传多样性,为研究过度捕捞、水电开发等人类活动对长鳍吻鮈的长期生态学效应及其物种适应机制提供基础数据,同时也为该物种保护策略的制定和调整提供科学数据支持。2014和2015年,于长江上游干流江津、宜宾、皎平渡和格里坪采集长鳍吻鮈,利用线粒体控制区序列的特异性引物,通过PCR扩增以及序列测定,获得125份长鳍吻鮈线粒体控制区序列。结果表明:125尾长鳍吻鮈样品共检测到多态位点25个,单倍型30种,平均单倍型多样性指数(Hd)和核苷酸多样性指数(Pi)分别为0.785和0.00140;中性检验(Tajima's D为-1.97524,P0.05;Fu's Fs为-31.374,P=0.000)和序列错配分布结果表明,长江上游长鳍吻鮈历史上经历过"遗传瓶颈"和种群扩张;分子方差分析(AMOVA)结果表明,群体间的遗传变异绝大部分来源于群体内部(99.07%),群体间无显著遗传分化(Fst=0.00933,P0.05);单倍型网络、Kinura 2-Parameter遗传距离和平均基因流均显示,4个长鳍吻鮈群体间存在广泛的基因交流,群体间无遗传分化。各群体间没有显著遗传分化,基因交流频繁,可将长江上游长鳍吻鮈作为单一的进化显著单元(ESU)进行管理。

Genetic Structure and Diversity of Rhinogobio ventralis in the Upper Yangtze River Obtained by Analysis of the Mitochondrial DNA Control Region

Rhinogobio ventralis (Teleostei, Cyprinidae, Gobioninae) is an important commercial fish in China, and is endemic to the upper reaches of the Yangtze River and its tributaries. In recent decades, as a result of water pollutin, overfishing and cascade hydropower development, natural resources of R. ventralis have dramatically declined and even faced the risk of extinction in its historical range. Fragmentation caused by damming may disrupt the connectivity of ecosystem and communication of fish populations, consequently, fish population genetic structure and diversity would be influenced. Understanding population genetic structure could be useful for informing management decisions and identify viable protection measures that could help conserve and restore the wild resources of R. ventralis. Meanwhile, estimation of genetic diversity and differentiation among natural populations would also benefit the artificial propagation programs of this species as well. In this study, using mitochondrial control region (D-loop) sequences, genetic structure and genetic diversity for 125 individuals from four sampling sections (Jiangjin, Yibin, Jiaopingdu and Geliping) in the upper reaches of the Yangtze River were analyzed. The results showed that there were 25 polymorphic sites and 30 different haplotypes among the 125 specimens, the average haplotype diversity index (Hd) and nucleotide diversity index (Pi) were 0.785 and 0.00140, respectively. Significant values of Tajima''s D (-1.97524, P<0.05) and Fu''s Fs (-31.374, P=0.000), together with uni-modal mismatch distribution, revealed that a recent genetic bottleneck or population expansion occurred in R. ventralis. Analysis of molecular variance (AMOVA) indicated that most of the genetic variation occured within groups (99.07%), and there was no significant differentiation among groups (FST=0.00933,P>0.05). Haplotype network, Kinura 2?Parameter distances and Nm value also showed a wide range of gene exchange among groups, with no genetic differentiation. In conclusion, these groups of R. ventralis in the upper reaches of the Yangtze River should be considered as a single management unit.