野生和近交稀有鮈鲫的遗传多样性

Genetic diversity of three Gobiocypris rarus populations and one inbreeding stock

用RAPD技术对稀有鲫近交 10代及 3个野生群体的遗传多样性和群体间差异进行了研究。无论从多态位点的比例、个体间的共带率还是从多样性指数来看 ,近交 10代的遗传多样性极低。在 2 2 6个RAPD位点中 ,野生群体有近半数的位点是多态的 ,Shannon多样性指数在 0 .2 911～ 0 .32 35间 ,表明自然群体保持了较丰富的遗传多样性。近交 10代与野生群体间遗传差异十分明显。野生群体间在 11～ 19个位点上的表型频率存在显著差异 ,总遗传多样性的 91.33%来自群体内 ,8.6 7%来自于群体间。

Genetic diversity of three Gobiocypris rarus populations and one inbreeding stock was studied using random amplified polymorphic DNA (RAPD) method. Materials of natural populations were collected from three counties of Sichuan Province, Hanyuan (HY), Guanxian (GX) and Pengxian (PX), where water system belongs to three tributaries of the Yangtz River, Dadu River, Minjiang River and Tuojiang River system, respectively. The inbreeding stock was the tenth generation descendant of a brother_sister mating (F 10 ) system whose parents were collected in Hanyuan. Percentage of polymorphic sites, genetic similarity and the Shannon's index of phenotypic diversity were used to analyze genetic diversity. The results showed the genetic diversity of F 10 was very low, whereas that of natural populations was relatively abundant. In natural populations, nearly half of the RAPD sites were polymorphic, and the average Shannon's index was 0.3235 (HY), 0.3075 (GX) and 0.2911(PX), respectively. Genetic similarity among individuals indicated that genetic diversity of HY and GX was higher than that of PX. Difference in genetic structure between F 10 and natural populations was fairly obvious. Although the differences on phenotype frequency were detected on 11 to 19 sites, no molecular marker was found to distinguish natural populations. Analysis on the coefficient of differentiation using Shannon's index revealed that 91.33% of total genetic diversity existed within natural populations and 8.67% among them. Treating the presence and absence of bands as two phenotypes, Chi_test (χ 2) and the analysis of Shannon's index was suggested to be effective approach for studying population differences.