大规格虹鳟(Oncorhynchus mykiss)收获期主要生长性状显性效应的遗传分析

以虹鳟(Oncorhynchus mykiss)优良品系选育第二世代群体作为试验群体,分别采用只含有加性效应和包括加性和显性效应的单性状动物模型估计了体质量、头长、体长、体宽、体厚等5个主要生长性状的加性遗传力和显性方差组分比率。只含有加性效应的模型结果显示,上述5个性状的遗传力在0.16—0.48之间,多为中等或较高遗传力;同时包括加性和显性效应的模型分析结果显示,上述5个性状的显性方差组分比率在0.24—0.67之间,均处于中等或较高水平。其中体长显性方差组分比率最低,为0.24,头长显性方差组分比率最高,为0.67。此外,与简单加性模型相比,同时包括加性和显性效应的模型估计的5个性状加性遗传力均有下降,在0.14—0.42之间,但是模型改变并没有影响到各性状加性遗传力大小数值的排序关系。本研究还发现,将显性效应纳入模型后,加性方差和随机残差都出现显著下降,提示只含有加性效应的混合模型中所期望的显性效应等非加性效应都可以简单地归入随机残差并不确切,如果将显性效应纳入育种规划,可以获得更大的遗传进展。

ESTIMATION ON DOMINANCE EFFECTS FOR BODY WEIGHT AND MEASUREMENT TRAITS AT HARVEST IN LARGE-SIZE RAINBOW TROUT ONCORHYNCHUS MYKISS

The second generation (G2) rainbow trout Oncorhynchus mykiss strain selected by the Heilongjiang Fishery Research Institute was used as the experimental population.Single-trait animal model with simple additive effect was used to estimate the heritabilities of five body growth traits, including body weight, head length, body length, body depth, and body thickness.The results show that the heritabilities of these traits ranged from 0.16 to 0.48, mainly at middle or high level.Single-trait animal model with both additive and dominance effects was also used in this study.The results show that the dominance variance component ratio ranged from 0.24 to 0.67;the dominance variance component ratio of body length was the lowest one at 0.24, and that of head length the highest at 0.67.Compared with the additive model, while the estimates of additive heritabilities by the single-trait animal model with both additive and dominance effects were decreased for all the 5 traits, but the model change did not affect the rank of the estimates.The study also found that when the dominance effect is included in the model, the additive variance and random residuals are declined significantly, suggesting that the expected dominance effects and other non-additive effect can be easily classified into random residuals at least not exactly for the animal model containing only the additive effect.If the dominance effect is under consideration, it might be able to obtain more genetic gain for the breeding program.