利用微卫星荧光多重PCR技术分析壳白长牡蛎3代人工选育群体的遗传多样性

为了探讨壳白长牡蛎人工选育对群体遗传变异的影响,实验利用4个多重PCR组合共10个微卫星标记分析了连续3代壳白长牡蛎人工选育群体和野生群体及基础群体的遗传多样性。结果发现,6个群体的平均等位基因数量为7.2~12.6,等位基因丰度为6.8~11.0,期望和观测杂合度分别为0.672~0.769和0.486~0.542;与野生群体相比,3代选育群体的平均等位基因数显著降低,但平均期望杂合度并无显著差异。哈迪—温伯格平衡检验结果显示,在60个群体—位点组合中有39个群体—位点组合显著偏离哈迪—温伯格平衡,近交系数F_(is)范围为0.215~0.342。群体间遗传分化指数F_(st)范围为0.005~0.076,处于中—低等的遗传分化水平。研究表明,虽然连续选育对群体的遗传多样性和遗传分化造成了一定程度的影响,但人工选育群体依然表现为较高的遗传多样性,仍可以一定的选择压力对选育群体进行人工选育。

Analysis of genetic diversity in mass selection lines of white-shell Pacific oyster (Crassostrea gigas) using microsatellite fluorescent multiplex PCR technique

To investigate the genetic variances in our successive selection strains for fast growth and white shell color of the Pacific oyster (Crassostrea gigas) during mass selection process, genetic diversity of three successive mass selection strains from G₁ to G₃, one based stock and two wild populations was analysed using multiplex assays with ten microsatellite markers. The study showed that the average allele number (N_a) ranged from 7.2 to 12.6 and the mean allelic richness (A_r) ranged from 6.8 to 11.0, the expected heterozygosity (H_e) and observed heterozygosity (H_o) ranged from 0.672 to 0.769 and 0.486 to 0.542, respectively. Compared to wild populations, the three successive mass selection strains showed significantly lower in the mean number of alleles and the mean allelic richness, but there was no significant difference in the average expected heterozygosity among the populations. There were 39 cases deviating significantly from Hardy-Weinberg equilibrium among the 60 population-locus cases (6 populations × 10 loci), and the inbreeding coefficient (F_is) ranged from 0.215 to 0.342. F_st values ranged from 0.005 to 0.076, showing low-moderate level genetic differentiation among the populations. The results suggest that the genetic variation has not been significantly affected by continuous mass selection and high genetic variability remains existing in the three successive selection strains, indicating that there is still potential for increased gains in future selective breeding programs.