凡纳滨对虾生长性状遗传参数的估计

采用平衡巢式设计方法和人工授精技术,每个雄体配3个雌体,构建了18个父系半同胞家系和54个母系全同胞家系.分别测定了每个母系生长到5月龄60个全同胞个体的体质量、全长、体长、头胸甲长、头胸甲宽、头胸甲高、第一腹节背高、第三腹节背高和第一腹节背宽9个生长性状,应用数量遗传学原理,采用方差和协方差分析的方法,估算了5月龄凡纳滨对虾生长性状的遗传力及各性状间的遗传相关及表型相关.结果表明,利用父系半同胞组内相关法估计的遗传力是凡纳滨对虾各生长性状遗传力的无偏估计值.其中,体质量、全长、体长、头胸甲长、头胸甲宽、头胸甲高、第一腹节背高、第三腹节背高和第一腹节背宽狭义遗传力的估计值分别为0.460、0.392、0.303、0.234、0.251、0.330、0.282、0.321和0.356,属于中高等遗传力范围,显示出较高的选择育种潜力.基于父系半同胞遗传协方差组分及表型协方差分别估计的各性状间的遗传相关及表型相关表明,各个性状间均表现出高的正相关,其中遗传相关在0.750 ～0.976,体质量—全长的遗传相关为最大(0.976),全长—第三腹节背高的遗传相关为最小(0.750),表型相关为0.507～0.947,体质量—全长为最大(0.947),第一腹节背高—头胸甲高为最小(0.507).经t检验,各性状间遗传相关及表型相关均达到极显著水平,表明以任意一个生长性状为参数进行选育,均可达到改良凡纳滨对虾生长情况的效果.

Genetic parameter estimation for growth traits of Pacific white shrimp(Litopenaeus vannamei)

Eighteen half-sib families and fifty-four full-sib families were constructed using methods of nest design and artificial insemination,in which each male mated three females.Sixty 5-month-old shrimp were measured for nine growth traits including the body weight(BW),the total length(TL),the body length(BL),the carapace length(CL),the carapace width(CW),the carapace depth(CD),the first abdominal segment depth(FASD),the third abdominal segment depth(TASD),and first abdominal segment width(FASW).According to quantitative genetics theory,the heritability of each growth trait,and the genetic and phenotypic correlation among the traits were statistically studied utilizing the method of variance and covariance analysis.The results showed that the heritability estimates in the narrow sense from intra-group correlation of paternal half-sib were precise and unbiased,and the heritability values for the above nine traits were 0.460,0.392,0.303,0.234,0.251,0.330,0.282,0.321 and 0.356,respectively.All of them belonged to moderate and high heritability,thus showed a high potential for selective breeding.The estimates of genetic correlation coefficients were 0.750-0.976,where the highest(0.976)was that between the BW and the TL,while the lowest(0.750)was seen between the TL and the TASD.The estimates of phenotypic correlation coefficients were 0.507-0.947,where the highest(0.947)was seen between the BW and the TL,while the lowest(0.507)was that between the FASD and the CD.Very significant difference was detected by t-test(P<0.01)among the nine growth traits for both genetic and phenotypic correlation coefficients,which indicate all the nine traits may respond favorably to direct and indirect selection for growth.