半滑舌鳎(Cynoglossus semilaevis)真、伪雄鱼群体表型和遗传性状分析

The Phenotypic and Genetic Traits Analysis of ZZ Males and ZW Males(Sex-Inverted Males) of Cynoglossus semilaevis

半滑舌鳎(Cynoglossus semilaevis)养殖群体中存在真雄鱼(ZZ)和伪雄鱼(ZW)现象,进行表型和遗传特征研究对其育种及优良苗种培育具有重要的意义。本研究以半滑舌鳎真、伪雄鱼群体及母系半同胞家系为研究对象,首先测定了性成熟半滑舌鳎的真、伪雄鱼群体的表型性状,对其性状进行了比较分析。结果显示,性成熟半滑舌鳎真、伪雄鱼的体重、全长、体长、体宽、头长、眼间距和眼径7个表型性状都存在极显著差异(P<0.01),伪雄鱼的生长速度比真雄鱼快。利用半滑舌鳎22对多态性微卫星标记,对2组半滑舌鳎真、伪雄鱼半同胞家系群体进行了遗传多样性分析。筛选出的22对引物扩增产物均具有多态性,4个半同胞家系群体中共检测到232个等位基因,群体平均等位基因数(N_a)均大于平均有效等位基因数(N_e);平均观测杂合度(H_o)均小于平均期望杂合度(H_e);平均多态信息含量(PIC)分别为0.4566、0.4254、0.5069、0.4795。22个多态性位点在4个半同胞家系群体中分别有3、3、4和5个位点显著偏离Hardy-Weinberg平衡。4个半同胞家系群体间的Nei￠s遗传距离为0.2101–0.5840,遗传相似性系数为0.5577–0.8105。本研究表明,半滑舌鳎真、伪雄鱼在生长性状上存在明显差异,同母系的真、伪雄鱼半同胞家系群体间的遗传相似系数较高,遗传距离较小,遗传多样性指标相近。

There are two kinds of male in the breeding populations of the half-smooth tongue sole Cynoglossus semilaevis, namely natural males （ZZ） and neomales （ZW）. It is of great importance to study their phenotypic and genetic characteristics since the knowledge can improve its breeding techniques and seed cultivation. In this study, 15 phenotypic traits were measured between mature ZZ males and ZW males （sex-inverted males） of C. semilaevis. Analysis showed that highly significant differences between ZZ males and ZW males existed in seven traits, including body weight, full length, body length, body width, head length, eye spacing and eye diameter, with the growth rate of ZW males being higher than that of ZZ males. Furthermore, comparative analysis of the population genetic structures was processed among maternal half-sib families between ZZ and ZW males by using 50 pairs of specific microsatellite markers. Results showed that 22 out of 50 pairs of PCR amplified markers were polymorphic. Among four half-sib families, 232 alleles were identified with relatively higher mean allelic number （Na） and mean expected heterozygosity （He） compared to mean effective allelic number （Ne） and observed heterozygosity （Ho） respectively. In addition, the average polymorphism information content （PIC） was 0.4566, 0.4254, 0.5069, 0.4795 among four half-sib families and there were 3, 3, 4 and 5 loci significantly deviated from Hardy-Weinberg expected genotypic frequencies. The Nei′s genetic distance among the four families was 0.2101–0.5840, and the genetic similarity was 0.5577–0.8105. The current study indicated that there were significant differences among growth traits between ZZ and ZW males of C. semilaevis. Between the maternal half-sib families, there was relatively high genetic similarity, low genetic distance and similar genetic diversity index.