Estes Suzanne, Phillips Patrick C
Department of Biology, Portland State University, Portland, Oregon 97201, USA.
Evolution. 2006 Dec;60(12):2655-60.
The pattern and extent of pleiotropic gene action can contribute substantially to the internal structure and shape of the additive genetic variance-covariance matrix (G)--a key determinant of evolutionary trajectories. We use data from our study (Estes et al. 2004) on the univariate effects of mutation in a mismatch-repair-defective strain, msh-2, of Caenorhabditis elegans to address the impact of increasing levels of selection on the magnitude and pattern of genetic covariance due to new mutations. Mutational covariances between three life-history traits are shown to exhibit a weak pattern of decline with increasing population size (increasing selection), while the orientation of mutational matrices remains reasonably constant. This suggests that mutations with smaller effects on fitness may tend to be slightly more confined in their influence than large-effect mutations (i.e., small-effect mutations reduce the magnitude of covariation between characters), but do not change the direction of this covariation.
多效基因作用的模式和程度会极大地影响加性遗传方差协方差矩阵（G）的内部结构和形状，而该矩阵是进化轨迹的关键决定因素。我们利用我们的研究（埃斯蒂斯等人，2004年）中关于秀丽隐杆线虫错配修复缺陷型菌株msh - 2中突变的单变量效应的数据，来探讨选择强度增加对新突变引起的遗传协方差大小和模式的影响。结果表明，随着种群规模增加（选择强度增加），三个生活史性状之间的突变协方差呈现出微弱的下降模式，而突变矩阵的方向保持相对稳定。这表明，对适合度影响较小的突变在其影响范围上可能比大效应突变更受限制（即小效应突变会降低性状间协变的大小），但不会改变这种协变的方向。
