快速近交对团头鲂遗传结构的影响和近交效应的估算

Effects on genetic structure from quick inbreeding and estimation of inbreeding response in cultured populations of Megalobrama amblycephala

利用RAPD技术定量分析了快速近交(全同胞近交,雌核发育)对团头鲂养育群体遗传结构的影响。经群体遗传学分析软件ARLEQUIN对RAPD图谱计算,在实测171个位点中,系统选育7代群体(F7)、全同胞近交4代群体(S4)及雌核发育2代群体(G2)的多态位点个数从大到小依次为F7(133)>S4(117)>G2(106);位点基因多样性从大到小依次为F7(0.30)>S4(0.28)>G2(0.24);根据这两个指标,一代雌核发育对基因纯合的影响力度为一代全同胞交配的3.3倍和6倍。3群体的群体内方差百分比为83.10%,群体间方差百分比为16.90%,固定性系数Fst(0.169)的p<0.01,遗传差异极显著,证明同选育群体相比,近交群体的基因型发生了明显异化。通过试验估算的近交系数值低于理论上的近交系数值,应是环境影响的存在和作用所致。

The changes of genetic structure by quick inbreeding (full-sib breeding, gynogenesis) on blunt snout bream have been analyzed by random amplified polymorphism DNA(RAPD). Using the population genetic analysis software (ARLEQUTN), in 171 observed loci, the 7th selected population (F7), 4th generation of systematic full-sib inbred population (S4) and a 2nd systematic gynogenesis population (G2) of blunt snout bream, the rank of number of polymorphic site was F7(133) > S4(117) > G2(106), and the rank of average gene diversity over loci in above three populations was F7(0.30), S4(0.28), and G2(0.24). Based on these two indicators, the effectiveness on the gene homogenization by one generation of gynogenesis was 3 and 6 times higher than that from one generation of full-sib inbreeding respectively. By AMOVA analysis, the variance percentage was 83.10% from within population and 16.90% from among population; Fixation index (Fst) was 0.169 (P < 0.01), which indicates the difference among above three populations is very significant. It is proved that inbreeding can cause a significant change in genotype of fish. Because of the existence of environmental influence, the estimated value of inbreeding co-efficient is lower than that of theoretical inbreeding co-efficient.