摘要
由于表型不连续以及表型与遗传效应呈非线性关系,阈性状在选择原理和种畜评价方法上不同于效量性状.本文就阈性状相应的特点进行了讨论.在个体选择中,阈性状的选择反应不仅仅取决于留种率,同时还取决于留种率与群体发生率的相对大小.在指数选择时,阈性状在指数中的出现使得指数不再是综合育种值的最佳线性估计;同时,指效的分布因阈性状而分为亚群,因而阈性状选择反应由亚群间和亚群内两个组分来估计是合理的.在多期望值的群体中,阈性状育种值估计的贝叶斯方法是理论上合理而估计精度又高的方法.这个方法建筑在广义线性模型和最大后验概率法之上,是一个非线性方法.由这个方法估计育种值需对非线性方程进行迭代.因而这个方法所需的计算费用较高.
Because of discontinuity of threshold trait and its non-linearity between observation and ge- netic effects,the selection theories and the method for breeding value prediction of the trait are different from quantitative trait.The characteristics of the threshold trait were discussed in this paper.In individual selection,the selection merit depends not only on selected proportion of candidates,but also on relative value of selected proportion to incidence of the trait.In index selection on a threshold trait together with a continuous trait,the index is no longer best linear predictor for aggregate breeding value.Meanwhile the in- dex is normally distributed no more and divided into different subpopulations in corresponding to classes of the threshold trait.It is therefore reasonable to predict the selection merit based on two resources,be- tween subpopulation und within subpopulation.For selection in a population of different expectation val- ues,Bayesian Method for breeding value prediction of threshold trait is theoretically correct and give bet- ter predictor than linear model method.The method is non-linear one based on generalized linear model and on the method of maximizing a posteriori density function.To predict the breeding value with the method,iterative procedure is necessary.High expences in calculation are the limitation of the method.
出处
《中国农业大学学报》
CAS
CSCD
北大核心
1993年第S1期44-51,共8页
Journal of China Agricultural University
关键词
阈性状
选择原理
育种值估计
非线性方法
threshold trait
selection theories
breeding value prediction
non-linear method
