福建牡蛎选育群体的遗传多样性

利用8个微卫星标记对福建牡蛎(Crassostrea angulata)基础群体、‘金蛎1号’选育系F6和野生群体进行遗传多样性分析。结果表明,每个位点在各群体的等位基因数为7~24个,各群体在所有位点的平均等位基因数为10.3~17.6个,平均等位基因丰度为9.8~16.8。平均观测杂合度和平均期望杂合度分别为0.655~0.662和0.788~0.872。经邦弗朗尼校正,哈迪–温伯格平衡检验结果显示,在24个群体–位点组合中18个群体–位点组合显著偏离平衡(P0.01)。群体内近交系数F_(is)值介于0.0095~0.2874,平均值为0.1992,遗传分化系数F_(st)介于0.0224~0.1627,平均值为0.0767,暗示选育群体中存在较低水平的非随机交配现象,属于中度偏低分化。研究表明,连续的选育对群体的遗传分化产生了一定的影响,但是,选育群体仍然具有较高水平的遗传多样性。

Genetic diversity in selected lines of Crassostrea angulata

On April 2009, a base population (F0) of the Fujian oyster, Crassostrea angulata, was selectively bred from the Fujiang and Guangdong local populations. A successive six-generation selection for golden shell and body weight was carried out to produce "Golden oyster 1#" (F6). In this study, eight microsatellite markers were analyzed in the base population, selected line F6, and wild populations of Crassostrea angulata. The number of alleles per locus ranged from 7 to 24. The average number of alleles and average allelic richness of the three populations at all loci had ranges of 10.3-17.6 and 9.8-16.8, respectively. Expected heterozygosity and observed heterozygosity were 0.655-0.662 and 0.788-0.872, respectively. In the Hardy-Weinberg equilibrium test, for the three populations and eight microsatellites, segregation distortion was significant for 12 of the 18 groups. The inbreeding coefficient (F_is) ranged between 0.0095-0.2874, with a mean of 0.1992. The F_st values were 0.0224-0.1627, with an average of 0.0767, indicating that there is a low level of inbreeding within populations and a high level of differentiation. Our results suggested that successive artificial breeding has a certain influence on genetic variation; however, there remains high genetic variability in the mass selection lines.