虹鳟体质量和主要体尺性状异速生长的遗传分析

摘要

采用联合异速生长遗传模型,对中国水产科学研究院黑龙江水产研究所渤海冷水性鱼类试验站培育的 F1杂交虹鳟(Oncorhynchus mykiss)和 F2杂交虹鳟的体质量和体尺性状异速生长进行了遗传分析,旨在为虹鳟及其他水产动物异速生长的遗传参数估计和实现体质量与体型的同步选育奠定理论基础。首先采用逐步回归分析法选择体尺性状对体质量的异速生长显著的性状,建立最优表型联合静态、动态异速生长指数模型,随后构建了两个用于遗传分析多个静态、动态异速生长的随机回归模型。虹鳟多个体尺性状相对体质量的异速生长遗传分析结果表明,体长与体质量具有较大的异速生长指数,为1.6338,且为正异速生长,而其他体尺性状相对体质量呈现负异速生长；遗传方差大小顺序和表型的偏异速生长指数一致,体宽和背鳍基长的异速生长的遗传相关最大,为−0.8675,其次为体长和体高,为−0.6194,最小的是−0.0217,为体高和体宽。体长与体质量的动态异速生长的加性遗传方差估计值为0.2929。结果表明,虹鳟体质量和主要体尺性状的异速生长是由遗传机制决定的,遗传方差及遗传相关的估计能够用来筛选优良亲本,这为进一步利用异速生长理论指导虹鳟及其他水产动物体质量与体型的同步选育提供了理论基础。%This is the first study to genetically analyze the relative growth of multiple partial body sizes in relation to the entire body size in rainbow trout, Oncorhynchus mykiss. The experimental groups were the first generation hybrid group (F1) and the second generation hybrid group (F2) obtained from the Bohai Cold Water Fish Experimental Station of the Heilongjiang River Fishery Research Institute, Chinese Academy of Fishery Sciences. By stepwise regression analysis, we optimized the phenotypic joint static/ontogenetic allometry scaling model to select the significant partial allometry scalings of multiple partial body sizes to entire body size. Two random regression models were constructed to genetically analyze multiple static/ontogenetic allometries. One model embeds the best joint static allometry model into the fixed and additive genetic effects of a simple animal model. The other model considers not only the fixed and addi-tive genetic effects on the best joint ontogenetic allometry model, but also the time dependence of permanent environ-mental effects in the repeated records animal model. The genetic parameter estimation of multiple allometries can be implemented with restricted maximum likelihood for a random regression model. Application of the models proposed here is illustrated to genetically analyze joint static allometry scalings of multiple body shape traits to body weight and ontogenetic allometry scaling of body lengths to body weights repeatedly observed at different growth times in rainbow trout. The results showed that body length has the largest significant allometric association with body weight, and the order in genetic variances for allometry scalings is likely to be consistent with that of phenotypic partial allometry scal-ings. The largest genetic correlation for allometry scaling was found to be−0.8675 between body width and dorsal-fin base length, followed by −0.6194 between body length and body depth, while −0.0217 was the minimum value. We estimated additive genetic variance for ontogenetic allometry of the body length to weight ratio as 0.2929. According to this study, the allometries of the morphological traits to body weights not only quantify differences in relative growth between the morphological traits to body weights, but also measure the relative genetic gains of the morphological traits to the body weights by genetic analysis. Thus, the genetic parameter estimation for allometries may be useful for guid-ance in synchronously improving morphological traits and body weights in rainbow trout. This will help genetic ma-nipulation of body shape as well as genetic improvement of body weight.