雌核发育团头鲂的形态和遗传特征分析

STUDIES ON MORPHOLOGICAL CHARACTERISTICS AND GENETIC ANALYSIS OF THE GYNOGENESIS BLUNT SNOUT BREAM(MEGALOBRAMA AMBLYCEPHALA)

利用团头鲂(Megalobrama amblycephala)正常二倍体群体作为对照组,对团头鲂减数分裂雌核发育二倍体群体的形态特征、染色体组型、性腺发育及遗传特征进行了分析。结果表明:雌核发育群体与正常群体在外部可数、可量性状上没有显著性差异(P>0.05);但雌核发育群体出现了尾鳍条数为12的畸形个体,与正常个体之间有较大的差异;两个群体的染色体条数都是48,核型均为18 m+26 sm+4 st;观察了20尾雌核发育个体的性腺,均为雌性个体且卵巢发育良好;采用10个微卫星标记对2个群体的遗传多样性分析,结果表明正常群体和雌核发育群体平均等位基因数分别为3.8个和1.7个,雌核发育群体的多态性显著低于正常群体,表明减数分裂雌核发育二倍体具有高度的遗传相似性,可作为一个很好的育种材料。

Using the normal diploid blunt snout bream(Megalobrama amblycephala) as control, we analyzed the morphological and genetic characteristics of the meiotic gynogenesis population. The results showed that there were no significant differences in the countable and measurable morphological traits between these two populations(P>0.05). However, deformed individuals with 12 caudal fin rays were found in the gynogenetic group, which was significantly different from control. The chromosome number of both control and gynogenesis groups was 48, with the same karyotype formula of 18 m+26 sm+4 st. The gonads from 20 gynogenetic individuals were observed, and all displayed the same normal ovary structures as control individuals. The genetic diversity of these two populations was analyzed using 10 microsatellite markers. The results showed that the average numbers of alleles in the control and gynogenetic populations were 3.8 and 1.7 respectively. The genetic diversity of the gynogenetic population was significantly lower than that of the control population. These results indicated that meiotic gynogenetic diploids have high genetic similarity and therefore were suitable for fixing traits of female.