Wang Hui, Chen Yao-Sheng
Guangdong Ocean University, Zhanjiang, China.
Yi Chuan Xue Bao. 2006 Apr;33(4):312-8. doi: 10.1016/S0379-4172(06)60056-5.
Selection is practically ubiquitous during marker-QTL linkage analysis with an experimental population. Thus, it is necessary to investigate the impacts of selection upon linkage analyses in order to obtain unbiased estimates of QTL position and effect. In this article, by exploiting flanking markers through the widely applied half-sib design, we have developed the structures of three variance components, i.e., variance component between marker genotypes, polygenic variance component and recombinant variance component within marker genotypes. Changes in these variance components under varying selection intensities were investigated in this study to formulate the effects of selection on various variance components. Results showed clearly that all variance components presented were quite sensitive to changes in selection intensity. As selection intensity increased, all variance components declined by differing extents in a quadratic fashion. Comparatively speaking, the variance between marker genotypes decreased most drastically, followed by the polygenic variance within marker genotypes and then the recombinant variance within marker genotypes, which suggested a decrease of power for QTL linkage analysis. Therefore, steps should be taken to avoid as much as possible the presence of selection in real populations, so as to further eliminate the negative effects of selection on QTL linkage analysis.
在利用实验群体进行标记-QTL连锁分析时，选择实际上普遍存在。因此，有必要研究选择对连锁分析的影响，以便获得QTL位置和效应的无偏估计。在本文中，通过广泛应用的半同胞设计利用侧翼标记，我们构建了三个方差成分的结构，即标记基因型间的方差成分、多基因方差成分和标记基因型内的重组方差成分。本研究调查了不同选择强度下这些方差成分的变化，以阐述选择对各种方差成分的影响。结果清楚地表明，所有呈现的方差成分对选择强度的变化都相当敏感。随着选择强度的增加，所有方差成分均以二次方式不同程度地下降。相对而言，标记基因型间的方差下降最为显著，其次是标记基因型内的多基因方差，然后是标记基因型内的重组方差，这表明QTL连锁分析的功效降低。因此，应采取措施尽可能避免实际群体中存在选择，以进一步消除选择对QTL连锁分析的负面影响。
