Studies on morphological characteristics and genetic analysis of the gynogenesis blunt snout bream (Megalobrama amblycephala)

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 (P0.05). 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.