【作者】 王忠卫；

【导师】 桂建芳； 吴清江；

【作者基本信息】 中国科学院研究生院（水生生物研究所） ， 遗传学， 2005， 博士

【副题名】鲢、鳙遗传多样性分析和纯系构建及长江三种鲿科鱼类的遗传结构研究

【摘要】 鲢、鳙是我国特有的养殖产量最大的淡水鱼类,广泛分布于长江、珠江、黑龙江流域和各大湖泊中。由于人类的活动,如人工建坝、过度捕捞等,加上人工繁殖缺乏科学的管理,鲢、鳙的种质资源出现了急剧下降的趋势。因此培育具有高产量、生长快速和抗病能力的鲢、鳙优良品种是育种的重要任务。纯系构建是育种中的一个重要方法,一般构建纯系的方法是通过连续的10 代以上的同胞兄妹交配或者连续两次以上的雌核发育结合人工性逆转来实现的,这对于生殖周期比较长的鲢、鳙,获得能够稳定遗传的纯系就比较困难。我们在方法上进行了一定的改进,通过人工雌核发育、性逆转再结合RAPD 分子标记,试图经过一代雌核发育快速建立了鲢、鳙纯系。因为长江-鄱阳湖-赣江特殊的江湖连接方式,加上长江和赣江是四大家鱼的重要的产卵场,我们借助线粒体DNA(ND5/6)的PCR-RFLP方法对鄱阳湖中鲢群体的来源问题进行了研究。鄱阳湖和赣江群体之间的遗传分化指数只为0.0346,因此我们完全可以认为鄱阳湖和赣江鲢群体没有明显的遗传分化,可以当作是同一个群体。而长江和鄱阳湖,长江和赣江鲢群体之间的遗传分化指数分别为0.1663和0.2020,因此我们认为长江和鄱阳湖之间,长江和赣江之间都有十分明显的遗传分化。所以我们认为,鄱阳湖鲢主要来自于赣江,而不是长江,这也和鲢产卵期的长江水位低于鄱阳湖的水位的情况是一致的。黄颡、瓦氏黄颡和长吻鮠是长江重要的鲿科经济鱼类,是长江上游和中下游都有分布的鱼类,这些鱼类被自然屏障长江三峡所分开。因此我们从长江不同地段采集了这几种鱼类,利用线粒体DNA 的部分片段(ND5/6、Cytb 和D-loop)更多还原

【Abstract】 Silver carp (Hypophthalmichthys molirix) and bighead carp (Aristichthys nobilis) are extensively distributed in the Yangtze River, Zhujiang River, Heilongjiang River and other lakes and they own the largest cultivation production in China. At present the germplasm qualities of the two species degenerate rapidly owing to lack of scientific management in artificial breeding and human activities, such as dam construction, overfishing. Therefore, to breed new varieties with a high yield, fast growth and disease resistance is an urgent task. Pure line construction is one of breeding methods and it achieves traditionally by carrying out sib mating of over 10 consecutive generations or two consecutive gynogenesis as well as sex reversal. But it is too long for silver carp and bighead carp because of their long life cycles. So the method was developed by adding RAPD marker selection to artificial gynogenesis and sex reversal. And we aimed to construct pure lines only through one gynogenesis. The river-lake connecting relationship among the Yangtze River, Poyang Lake and Ganjiang River is very especial and there are lots of spawning grounds in the Yangtze River and Ganjiang River. So we investigated genetic construct of the silver carp from the Yangtze River, Ganjiang River and Poyang Lake for understanding which population contributing most to Poyang Lake population. The value of PhiST was 0.0346 between Poyang Lake population and Ganjiang River population and this indicated that there was no apparent differentiation between them. So the two populations could be considered as one population. It was 0.1663 and 0.2020 between the Yangtze River population and Poyang Lake population and between the Yangtze River and Ganjiang River respectively, which showed their significant differentiation. So we made a conclusion that the composition of Poyang Lake silver carp population consisted mainly of Ganjiang River population. It was coincident with the fact that the water level of Poyang Lake outlet had always been higher than that of the Yangtze River during the spawning season of the silver carp. Yellow catfish, darkbarbel catfish and longsnout catfish are economic fishes distributing along the Yangtze River. But these fishes were separated by the natural barrier, the Three Gorges. The genetic diversities and genetic structure of these fishes were studied by the methods of PCR-RFLP and direct sequence of mitochondrial DNA fragments (ND5/6, Cytb and D-loop). The results indicated that apparent differenciation existed between the populations from upstream and mid-down stream of the Yangtze River. But there was no apparent differenciation among the populations from mid-down stream and it was concerned with the absence of barriers to prevent gene flow. Yellow catfish and darkbarbel catfish were very uniform in morphology and reproduction mode. However, with regard to genetic variances of Yellow catfish and darkbarbel catfish, the compositions of genetic variance were different. And it may result from the different life history of the two fishes. As for long snout catfish, the genetic diversities are very low. What’s more, the abundance of long snout catfish is very low at present. So appropriate measures should be taken to conserve long snout catfish.更多还原