Gavrilets S, Hastings A
Division of Environmental Studies, University of California, Davis 95616, USA.
Genet Res. 1995 Feb;65(1):63-74. doi: 10.1017/s0016672300033012.
We study the transient dynamics of the genotypic variance of an additive trait under stabilizing selection, recombination and random drift. We show how interaction of these factors determines the form and the rates of change of different components of the genotypic variance. Let Vg be the genic variance of the trait and CL be the contribution of linkage disequilibrium to the genotypic variance. We demonstrate that the dynamics of the system on the plane (Vg, CL) are typically characterized by a quick approach to a straight line with slow evolution along this line afterwards. We show that the number of loci, n, and the population size, N, affect the expected dynamics of Vg mainly through the ratio N/n. We use our analytical and numerical results in interpreting the published results of artificial stabilizing selection experiments. The analysis suggests that it is drift and not selection that most likely led to the reduction of genetic variability in most of these experiments. Even very strong stabilizing selection only slowly removes polygenic variability from populations.
我们研究了在稳定选择、重组和随机漂变作用下加性性状基因型方差的瞬态动力学。我们展示了这些因素的相互作用如何决定基因型方差不同组分的变化形式和速率。设Vg为性状的基因方差，CL为连锁不平衡对基因型方差的贡献。我们证明，在平面（Vg，CL）上系统的动力学通常表现为快速趋近一条直线，随后沿该直线缓慢演化。我们表明，基因座数量n和种群大小N主要通过N/n的比值影响Vg的预期动力学。我们利用分析和数值结果来解释已发表的人工稳定选择实验结果。分析表明，在大多数这些实验中，最有可能导致遗传变异性降低的是漂变而非选择。即使是非常强的稳定选择也只能缓慢地从种群中去除多基因变异性。
