长江流域铜鱼和圆口铜鱼的遗传多样性

Genetic diversity of bronze gudgeon (Coreius heterodon) and largemouth bronze gudgeon (C. guichenoti ) in Yangtze River Basin

利用线粒体DNA控制区序列多态性分析了长江流域铜鱼（Coreius heterodon）和圆口铜鱼（Coreius guichenoti）各4个群体的遗传结构；同时利用9对自行开发的多态性微卫星标记分析圆口铜鱼4个群体的遗传结构。结果显示，铜鱼线粒体DNA（mtDNA）D-loop序列共检出22个多态位点，28种单倍型，平均单倍型多样性指数（h）和核苷酸多样性指数（7r）分别为0．849和0．00257。圆口铜鱼线粒体DNA（mtDNA）D-loop序列共检出18个多态位点，28种单倍型，平均单倍型多样性指数和核苷酸多样性指数分别为0．902和0．00424。分子变异分析（AMOVA）结果提示，铜鱼和圆口铜鱼分别有98．80％和99．17％的遗传变异发生于群体内部，表明铜鱼和圆口铜鱼未出现种群分化。选用的9个微卫星标记在圆口铜鱼群体中共检测到48个等位基因；群体平均观测杂合度在0．631～0．753之间；平均期望杂合度为0．598-0．728：平均多态信息含量为0．548～0．670。结果表明，长江流域铜鱼遗传多样性较低，长江上游圆口铜鱼遗传多样性较高，且均未出现种群遗传分化。圆口铜鱼SSR固定指数为0．12l58，高于D．1oop固定指数，显示SSR标记对圆口铜鱼群体间遗传差异的检测更为灵敏。[中国水产科学，2008，15（3）：377-385]

The bronze gudgeon（Coreius heterodon）and largemouth bronze gudgeon （C. guichenoti） are economically important species in Yangtze River. The stocks declined drastically in recent years due to dam construction, over-fishing, and water pollution. Little is known about their population genetic structure, which has become an obstacle to further research on the protection, management, rational exploitation and sustainable utilization of these fish. In this study, mitochondrial DNA D-Loop sequences were used to investigate the genetic diversity of 102 bronze gudgeon individuals, collected from the upper （Wanzhou, 23 individuals）, middle （Shangahai, 30 individuals： Hukou, 24 individuals）, and lower （Changshu, 25 individuals） reaches of the Yangtze River, and the genetic diversity of 132 largemouth bronze gudgeon individuals, collected from the upper reaches （Yibin, 31 individuals; Banan, 33 individuals： Fuling, 34 individuals; Zhongxian, 34 individuals） of Yangtze River. Additionally, 9 polymorphic simple sequence repeats （SSR）loci were used to assess the genetic diversity of bronze gudgeon from four sites in the upper reaches of Yangtze River. The results showed that among the aligned mtDNA D-Loop sequences of 760 basepair in bronze gudgeon, 22 variable sites, including 11 transition substitution sites, 5 transversion sites and 6 insertion sites among all individuals, recovered 28 haplotypes, and the haplotype diversity （p） and nucleotide diversity （h） were 0.849 and 0.002 6, respectively. Among the aligned mtDNA D-Loop sequences of 923 basepair in largemouth bronze gudgeon, 18 variable sites, including 15 transition substitution sites, 1 transversion sites and 2 insertion sites among all individuals, recovered 28 haplotypes, and the haplotype diversity （p） and nucleotide diversity （h） were 0.902 and 0.004 2, respectively. The haplotype diversity （p） and the nucleotide diversity （h） were lower in bronze gudgeon than in largemouth bronze gudgeon, which indicated that the genetic diversity of bronze gudgeon was lower than that of largemouth bronze gudgeon. Analysis of molecular variance （AMOVA） suggested that the genetic divergences, occurring within the populations in bronze gudgeon and within the populations in largemouth bronze gudgeon, were 98.8% and 99.17%, respectively. Nine polymorphic simple sequence repeats （SSR） loci identified a total of 48 alleles in largemouth bronze gudgeon, with observed heterozygosity （Ho）value ranging from 0.631 to 0.753, expected heterozygosity （He） value ranging from 0.598 to 0.728 and polymorphism information content （PIC） value ranging from 0.548 to 0.670. The results suggest that while the genetic diversity of the bronze gudgeon in Yangtze River is low, the genetic diversity of largemouth bronze gudgeon in the upper reachesof Yangtze River is under in good condition. Very little genetic differentiation occurred among the populations of bronze gudgeon in Yangtze River and among the populations of largemouth bronze gudgeon in the upper reaches of Yangtze River. The Fst of S SR （0.121 58） was higher than that of D-loop in Coreius guichenoti, demonstrating that SSR was more suitable for analysis of genetic polymorphism in Coreius guichenoti. [Journal of Fishery Sciences of China, 2008, 15 （3） ： 377-385 ]