大黄鱼群体遗传多样性的微卫星DNA分析

摘要

通过建立大黄鱼部分基因组文库,应用PCR法筛选到55个含微卫星DNA位点的阳性克隆,选择其中8个序列设计微卫星引物,在这8个微卫星位点中得到91个等位基因片段,各位点等位基因数6～22个,平均观测杂合度Ho为0.404 7,平均期望杂合度He为0.775 6,多态信息含量(PIC)平均值为0.754 5,结果显示,所选择的8个微卫星位点均表现出较高的多态性.利用这些微卫星引物对大黄鱼不同群体进行遗传多样性分析,结果表明,大黄鱼种群中仍存在较高的遗传变异,但微卫星等位基因频率大多偏离了Hardy-Weinberg平衡,且不同群体间存在较高的基因流(Nm=2.699 8),表明大黄鱼种群存在较严重的近亲繁殖且各群体间有着较频繁的基因交流.对不同地理群体的聚类分析结果支持了中国沿海大黄鱼种群大致划分为3个不同地理种群的论证.%A partial genomic library of Pseudosciaena crocea was constructed in this paper. The PCR-based screening library method was used to isolate microsatellite loci containing the repeat motif of (CA)nand (GA)n. Total 55 positive clones were isolated. 32 positive clones were sequenced. 8 pairs of primers were designed based on the unique sequences flanking each motif with the software Primer3. Genomic DNA from 92 tested individuals was applied to evaluate the amplification efficiency of these primers and polymorphism of these markers. GENPOP (v. 1. 32) software was performanced to analyse the allele data. The number of the alleles per locus varied from 6 to 22. Mean observed and expected heterozygosities {Ho and He), were 0.404 7 and 0.775 6, respectively. These markers showed polymorphism information content between 0. 365 1 and 0. 928 1. Four P. crocea stocks from different geographic regions were served to evalucate the population genetic structure with these microsatellites DNA logi. The results showed that genetic differentiation were not significant between all stocks (Fst =0.084 8). FJS values within each stock were something high (average 0. 436 7) and tests for all sampled populations contained unique alleles. The findings indicated that the populations of P. crocea still possessed variation between tested stocks. It may be caused by the large geographical scales of sample stocks. It means if conducting the suitable conservation and management strategies, the germplasm of large yellow croaker could renew in some measure. The observed allele frequency of most of microsatellites loci deviated from Hardy-weinberg equilibrium, I. E. population mating system may not follow the random principle. The gene flow between all four stocks were 2. 699 8, data implied that there were significant gene exchange between stocks. Clustering analysis results supported that P. crocea from China's coast would divided into three different geographic populations.