凡纳滨对虾家系幼虾淡化和养殖阶段存活性状遗传参数估计

摘要

准确估计育种目标性状的遗传参数,评估其改良潜力,是制定育种方案、进行选择育种工作的重要前提条件.本研究对100个凡纳滨对虾(Litopenaeus vannamei)家系15000尾仔虾个体进行淡化和低盐养殖实验,分析了2个阶段家系间存活率的差异,并进一步估计存活性状的遗传力.结果显示,2个阶段存活率范围分别为19.3%~100.00%和11.86%~99.22%,平均存活率分别为66.7%和67.5%.家系幼虾期总体存活率为6.67%~90.67%,平均存活率为46.91%.统计分析显示,2个阶段家系间存活率差异极显著(P<0.01),存活率的相关系数为0.61(P<0.01),呈中度正相关(0.32.58);基于A+C模型, 3个阶段遗传力转换后估计值分别为0.06、0.05和0.07,与0相比,估计值均未达到显著水平(z<1.96).基于A模型和A+C模型,获得的2个阶段间家系存活性状育种值的相关系数分别为0.41±0.09和0.48±0.09.由于半同胞家系比例仅为47%,家系单独在网箱中测试,家系遗传效应与共同环境效应部分混淆,因此,基于A模型获得的遗传力估计值偏高,基于A+C模型获得的遗传力估计值偏低.本研究结果表明,通过多代选择育种,可以改良凡纳滨对虾幼虾淡化和低盐度养殖存活性能.%Genetic parameters of breeding object traits are important to design breeding scheme and evaluate selection response before performing a selective breeding program. In this study, a total of 15000 individuals from 100 families of Litopenaeus vannamei at the juvenile stage were desalinated and reared at a low salinity of 5 to explore the survival rate and the heritability. The results showed that the range of the survival rate at the desalination stage and culture stage were 19.33%–100.00% and 11.9%–99.2%, and the average survival rate were 66.7% and 67.5%, respectively. The range of the overall survival rate at the juvenile stage was 6.67%–90.67% with the average survival rate 46.91%. There were significant differences on the survival rate between families at two stages (P<0.01). There was significant and moderate positive correlation on the survival rate of families between two stages (r=0.61, P<0.01). The heritabilities of survival for two stages were estimated by the model of the additive genetic effect (A) and the model combining A and the common environmental effect (C). Based on the A model, the heritability of survival for the desalination stage, culture stage and combination of two stages were 0.09, 0.10 and 0.14, respectively, which were significantly different from zero (z﹥2.58). Based on the A+C model, heritability of survival were 0.06, 0.05 and 0.07, respectively, which were not significantly different from zero (z<1.96). The genetic correlation on the survival rate of families between two stages for the A and A+C models were 0.41±0.09 and 0.48±0.09, respectively. The additive genetic effect was partially confounded with the common environmental effect because the proportion of half-sib families to full-sib families was only 47% when each family were cultured in a separate cage. Therefore, the heritability estimates based on the A model were overestimated, and the heritability estimates based on the A+C model was underestimated. The results implied that the adaptability of low salinity for Pacific white shrimp can be improved through a selective breeding program.