Adaptive Fixation in Two-Locus Models of Stabilizing Selection and Genetic Drift
Adaptive Fixation in Two-Locus Models of Stabilizing Selection and Genetic Drift
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DOI：
10.1534/genetics.114.168567
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发表时间：
2014-10-01
期刊：
影响因子：
3.3
通讯作者：
Stephan, Wolfgang
中科院分区：
文献类型：
--
作者：
Wollstein, Andreas;Stephan, Wolfgang
数量遗传学和群体遗传学之间的关系已经研究了近世纪，几乎是从这两个学科存在以来。在这里，我们要问的是，在多大程度上的定量遗传模型中，选择被假定为对多基因性状进行操作，预测适应性固定，可能会导致基因组中的足迹（选择性扫描）。我们研究两个位点模型的稳定选择（有和没有遗传漂变）的模拟和分析。对于对称可行性选择，我们发现，如果初始等位基因频率从中性位点频谱中采样，并且效应大小均匀分布，则约16%的轨迹可能导致固定。然而，如果种群在经历环境变化时是预适应的（即，位于模型的一个平衡中），固定概率急剧下降。在其他具有一般活力或最佳偏移的双位点模型中，适应性注视的比例可能增加到> 24%。同样，遗传漂变导致更高的固定概率。替代数量遗传学模型的预测，初始条件和效应大小分布也进行了讨论。
The relationship between quantitative genetics and population genetics has been studied for nearly a century, almost since the existence of these two disciplines. Here we ask to what extent quantitative genetic models in which selection is assumed to operate on a polygenic trait predict adaptive fixations that may lead to footprints in the genome (selective sweeps). We study two-locus models of stabilizing selection (with and without genetic drift) by simulations and analytically. For symmetric viability selection we find that approximate to 16% of the trajectories may lead to fixation if the initial allele frequencies are sampled from the neutral site-frequency spectrum and the effect sizes are uniformly distributed. However, if the population is preadapted when it undergoes an environmental change (i.e., sits in one of the equilibria of the model), the fixation probability decreases dramatically. In other two-locus models with general viabilities or an optimum shift, the proportion of adaptive fixations may increase to >24%. Similarly, genetic drift leads to a higher probability of fixation. The predictions of alternative quantitative genetics models, initial conditions, and effect-size distributions are also discussed.