Kearney J F, Navarro P, Haley C S, Villanueva B
Scottish Agricultural College, West Mains Road, Edinburgh, United Kingdom.
J Anim Sci. 2009 Mar;87(3):850-9. doi: 10.2527/jas.2008-1099. Epub 2008 Nov 7.
In this study the effect of artificial selection on BLUP EBV for production traits on the allele frequencies of a pleiotropic QTL affecting both production and disease susceptibility was investigated. Stochastic simulations were used to model artificial selection on a production trait that is controlled, in part, by a biallelic QTL that also controls susceptibility to disease. The QTL allele increasing production also increased susceptibility to disease. Different modes of action and proportions of variation accounted for by the QTL were assessed for the production trait. The main results indicated that alleles that confer susceptibility to the disease could be maintained in the population over a long period, depending on the mode of action of the QTL. In addition, the results of the study indicate that, under various conditions, it is possible to find pleiotropic QTL that control 2 traits despite these traits appearing to be uncorrelated. Therefore, in practice, an estimate of the genetic correlation between 2 traits may be misleading when the presence of such a QTL exists. The results of this study have implications for breeding programs. For example, if a pleiotropic QTL exists that favors heterozygotes for a production trait, it would be very difficult to remove disease susceptibility alleles via traditional selection methods.
在本研究中，调查了人工选择对生产性状的最佳线性无偏预测（BLUP）估计育种值（EBV）的影响，该生产性状受一个影响生产和疾病易感性的多效性数量性状位点（QTL）的等位基因频率控制。采用随机模拟对一个部分受双等位基因QTL控制的生产性状进行人工选择建模，该QTL也控制疾病易感性。增加生产性能的QTL等位基因也会增加疾病易感性。评估了QTL对生产性状的不同作用模式和变异比例。主要结果表明，取决于QTL的作用模式，赋予疾病易感性的等位基因可能会在群体中长时间维持。此外，研究结果表明，在各种条件下，有可能找到控制两个性状的多效性QTL，尽管这些性状看似不相关。因此，在实际中，当存在这样一个QTL时，对两个性状之间遗传相关性的估计可能会产生误导。本研究结果对育种计划具有启示意义。例如，如果存在一个有利于生产性状杂合子的多效性QTL，那么通过传统选择方法去除疾病易感性等位基因将非常困难。
