凡纳滨对虾(Litopenaeus vannamei)选育群体与杂交群体遗传多样性差异及其在低温条件下生长性能的比较

选取连续3年选育的凡纳滨对虾(Litopenaeus vannamei)群体作为选育群体(SP),选育群体与引进的凡纳滨对虾群体的杂交F1代群体(HP),探究了这2个群体在低温条件下的生长性能及遗传多样性的差异.结果显示,在生长性能方面,HP群体与SP群体的平均体重分别为(13.18±3.65)g和(12.20±3.14)g,变异系数(CV)分别为27.69％和25.74％.HP群体的体重和其他可测量性状的平均值均大于SP群体.单因素方差分析(One-way ANOVA)表明,2个群体体重(BW)和第3腹节宽(TASW)存在极显著差异(P＜0.01).HP群体的特定增长率(SGR)和绝对增重率(AGR)分别为(5.09±0.61) ％/d和(0.26±0.60) g/d,SP群体的SGR和AGR分别为(4.94±0.57) ％/d和(0.24±0.63) g/d,HP群体的SGR和AGR均极显著高于SP群体(P＜0.01),表明HP群体相对于SP群体有着明显的生长优势.在遗传多样性方面,HP群体的平均等位基因数(Na=7.9)略高于SP群体(Na=7.6).HP群体和SP群体的平均多态信息含量(PIC)分别为0.63和0.62,均为高度多态.2个群体的平均观测杂合度(Ho)分别为0.492(HP群体)和0.483(SP群体),平均期望杂合度(He)分别为0.675(HP群体)和0.663(SP群体),HP群体的He和Ho均略高于SP群体,表明HP群体相比SP群体有着更加丰富的遗传多样性.遗传分化分析表明,2个群体间遗传分化指数(Fst)为0.1556,表明群体间遗传分化水平显著.

The Difference of Genetic Diversity and the Comparison of Growth Performance Between Selected Population and Hybridized Population of Pacific White Shrimp (Litopenaeus vannamei) Under Low Temperature Conditions

To breed the Litopenaeus vannamei that could resist low temperature during production cycle, this study investigated the heterosis advantage in breeding program and compareds the growth performance and genetic diversity between two populations under the low temperature conditions. One population, namely the Selected Population (SP), was bred for three consecutive years in our aquatic laboratory, whereas the other one, the Hybrid Population (HP), came from the hybridization of the Selected Population and the Introduced Population. The results showed that the growth performance of HP was significantly higher than SP. The average body weight of HP and SP shrimps were (13.18±3.65) g and (12.20±3.14) g respectively, and the coefficient of variation were 27.69% and 25.74%, respectively. The average body weight and other measurable traits in HP were higher than those in SP. The results of One-way ANOVA indicated that there were significant differences (P<0.001) between HP and SP in both body weight and TASW. The specific growth rate (SGR) and absolute growth rate (AGR) in HP were (5.09±0.61) %/d and (0.26±0.60) g/d, respectively. By comparison, in SP group, the SGR was (4.94±0.57) %/d and the AGR was (0.24±0.63) g/d, significantly lower (P<0.01) than the HP group. The results of genetic diversity analysis showed that the Na of HP (Na=7.9) was slightly higher than SP (Na=7.6). The average polymorphic information content (PIC) of HP and SP was similar as 0.63 and 0.62, respectively, both belong to the relatively high polymorphism level. The average observed heterozygosity (Ho) of HP and SP was 0.492 and 0.483, respectively, and the expected heterozygosity (He) was 0.675 and 0.663, respectively. Both Ho and He in HP were higher than that in SP, suggesting that HP had higher genetic diversity abundant compared to the SP. The analysis of genetic differentiation indicated that the genetic differentiation was significant between HP and SP, with the genetic differentiation index (Fst) between HP and SP was 0.1556. The results of this study provides a genetic background and production experience of L. vannamei for breeding low temperature breed and crossbreeding technique.