马氏珠母贝选育群体4个世代的遗传变异

采用9个多态性微卫星位点分析马氏珠母贝(Pinctada fucata)壳高选育品系(JCS)4个世代的遗传多样性与遗传结构的变化。结果表明, 随着选育的进行,  4个世代每个位点的平均有效等位基因数(N_e)从2.096下降至1.435, 平均等位基因丰度(R_s)从3.556下降至 2.556, 平均观测杂合度从0.492渐次下降至0.269, 遗传多样性呈明显的下降趋势。随着选育世代的增加, 从等位基因频率的变化来看, 部分呈上升趋势, 部分呈下降趋势, 部分基本保持稳定, 其中, 一些低频基因甚至会趋于消失。在所有等位基因中, 大部分的频率呈随机变化趋势, 并在不同的世代间上下波动; HHM20- 158 bp的频率呈有规律的变化, 由中高频逐步上升至高频, 呈富集趋势。结论认为, 经过4代的选育, 马氏珠母贝选育群体遗传多样性呈降低趋势, 遗传结构趋于稳定。本研究旨在为后续的马氏珠母贝选育策略提供理论指导。

Genetic variation during four generations of selective breeding in the pearl oyster Pinctada fucata

We documented variation in the genetic diversity and genetic structure of P. fucata during selection over four-generations for shell height using nine microsatellite loci. The mean effective number of alleles per locus (N_e) ranged from 1.435 to 2.096 among the four JCS generations. The mean allelic richness (R_s) decreased from 3.556 to 2.556, the mean H_o decreased from 0.492 to 0.269, suggesting there was a decrease in genetic diversity. In general, the allelic frequency remained stable over the four generations, but fluctuated up and down, apparently randomly, between generations. For example, the frequency of the HHM20-158 bp allele changed regularly from mid to high levels. Our results suggest that persistent selective breeding resulted in reduced genetic diversity and somewhat stable genetic structure in pearl oyster.