【作者】 司从利；

【导师】 章群；

【作者基本信息】 暨南大学 ， 生态学， 2012， 硕士

【摘要】 鳜鱼隶属鲈形目（Perciformes）鮨科（Serranidae）鳜亚科（Sinipercinae）。鳜鱼作为东亚地区特有的名贵鱼类，具有较高的生态价值、经济价值和科研价值。鳜鱼因其肉质细嫩、味道鲜美、营养丰富，而受到广大消费者的欢迎。长期以来，受自然环境因素和人为因素两方面的影响，珠江水系鳜鱼的遗传多样性急剧下降。一方面，气候异常变化、地质灾害频发破坏了鳜鱼的生境；另一方面过度捕捞、人工养殖、环境污染及修建水坝，不仅使鳜鱼的个体迅速下降、种质资源受到破坏，而且影响了不同群体间的基因交流。不仅珠江，在长江流域鳜鱼也面临着遗传多样性下降的严峻趋势。作为东亚地区特有的重要经济鱼类，鳜鱼急需加强保护。本文基于线粒体细胞色素b基因，对珠江水系干流及其4个主要支流共计126尾鳜鱼进行遗传多样性分析。得到如下结果：1.遗传多样性方面，珠江7个地理群体的126尾鳜鱼中，共发现16个单倍型，平均单倍型多样性（Hd）为0.773，核苷酸多样性（Pi）为0.00195，呈现高单倍型多样性低核苷酸多样性的特点。表明鳜鱼可能经历过瓶颈效应或奠基者效应，短期内通过变异积累了足够的单倍型多样性，但相同时间却不足以积累核苷酸多样性。其中以柳州群体遗传多样性最高，而三江群体遗传多样性最低，这可能是因为三江地区地质结构复杂，鱼类生活环境较差，而柳州地区区域稳定性较好且处于柳江干流，便于与其他群体进行基因交流。2.遗传分化方面：基于线粒体Cytb基因的NJ系统树中，不同地理群体的鳜鱼没有表现出明显的地理聚群现象，说明没有形成明显的地理结构。珠江水系7个地理群体之间的遗传距离均为0.002，各群体内部遗传距离在0.001-0.002之间。AMOVA分析结果表明，群体间差异仅为8.40%，而群体个体间差异高达88.04%，说明珠江不同水体之间的差异主要来自群体个体间的变异。珠江水系7个地理群体中，三江群体和其他群体之间均发生了不同程度的遗传分化，这可能是由于三江处于柳江支流上游，远离干流，且三江地理环境较差，故阻碍了三江群体同其他群体间的基因交流。3.种群扩张方面：歧点分布图、Tajima’s D和Fu’s Fs中性检验结果都表明，在7个鳜鱼群体中，三江群体和柳州群体历史上发生过种群扩张，而鳜鱼作为一个大的群体没有发生过扩张。估计出鳜鱼三江群体、柳州群体的种群扩张时间分别为15~40万年前、18~45万年前。更多还原

【Abstract】 S.chuatsi sensu lato (Sinipercinae:Serranidae:Perciformes), were rare freshwaterfishes and endemic in East Asia. They had important economic value, ecologicalvalue and scientific value. S.chuatsi sensu lato for its meat And refine, delicious intaste good taste and eutrophy, by the general consumers’ welcome.For a long time,affected by natural factors and Human factors, S.chuatsi sensu lato of the mandaringenetic diversity decreasing sharply. on the one hand, unusual climate change,geological disasters destroyed S.chuatsi sensu lato habitat;on the other hand,overfishing, artificial breeding, environment pollution and built DAMS. Not onlymake S.chuatsi sensu lato individual fell rapidly, germplasm resources to sabotage,and affect different groups of communication between genes. Not only the pearl river,in the Yangtze river basin S.chuatsi sensu lato is also facing a genetic diversity of thedecline of the serious trend. As the east Asia region important special economic fish,S.chuatsi sensu lato in genetic diversity protection is urgently needed.This paper, based on the mitochondria cytochrome b genes, Sum to126S.chuatsisensu lato in the pearl river water system and its four main tributaries Geneticdiversity analysis. Results were as follows:1. Genetic diversity: In126S.chuatsi sensu lato from7geographical populationsof the pearl river,16haplotypes were found. All the group showed high haplotypediversity (Hd is0.773) and low nucleotide diversity (Pi is0.00195). Indicating thatS.chuatsi sensu lato populations may have experienced a recent bottleneck or foundereffect, as sufficient haplotype diversity could be accumulated in short-term bymutation, but it were not enough to accumulate nucleotide diversity. In S.chuatsisensu lato populations the highest genetic diversity were found in Liu zhou population,and the lowest were in San jiang population. This may be because of the complexgeological structure sanjiang region, fish life environment is bad, Liuzhou region andregional stability is good,and in liujiang mainstream, With other groups to geneexchange convenient 2. Genetic differentiation: In Neighbor-joining tree based on mtDNA Cytbsequences, different geographical population in S.chuatsi sensu lato didn’t showobvious geographic cluster phenomenon, show that no obvious geographic structure.The genetic distance was form0.001to0.002within groups and was0.002betweentwo of them. Analysis of molecular variance(AMOVA) indicated that8.40%variations were found among groups, and only88.04%variations existed withinpopulations. Showed that the differences between different geographical populationsin the Pearl River are mainly within group.7geographical population in the pearlriver water system, Sanjiang group and other groups all happened between differentdegree of genetic differentiation, this may be due to the total tributaries in sanjiangupstream, away from the mainstream, and sanjiang geographic environment is bad, Sohindered sanjiang group with other groups of communication between genes.3. Population expanding: Mismatch distribution,Tajima’s D and Fu’s Fs neutraltests showed that historical population expansion only occurred in sanjiang populationand liuzhou population, but S.chuatsi sensu lato as a whole didn’t occured populationexpansion. The population expansion of sanjiang population and liuzhou populationappeared in15~400000years ago、18~450000years ago respectively.更多还原