Good Benjamin H, Desai Michael M
Department of Organismic and Evolutionary Biology, Department of Physics, and FAS Center for Systems Biology, Harvard University, United States.
Theor Popul Biol. 2013 May;85:86-102. doi: 10.1016/j.tpb.2013.01.005. Epub 2013 Jan 18.
Evolutionary dynamics and patterns of molecular evolution are strongly influenced by selection on linked regions of the genome, but our quantitative understanding of these effects remains incomplete. Recent work has focused on predicting the distribution of fitness within an evolving population, and this forms the basis for several methods that leverage the fitness distribution to predict the patterns of genetic diversity when selection is strong. However, in weakly selected populations random fluctuations due to genetic drift are more severe, and neither the distribution of fitness nor the sequence diversity within the population are well understood. Here, we briefly review the motivations behind the fitness-distribution picture, and summarize the general approaches that have been used to analyze this distribution in the strong-selection regime. We then extend these approaches to the case of weak selection, by outlining a perturbative treatment of selection at a large number of linked sites. This allows us to quantify the stochastic behavior of the fitness distribution and yields exact analytical predictions for the sequence diversity and substitution rate in the limit that selection is weak.
进化动力学和分子进化模式受到基因组连锁区域选择的强烈影响，但我们对这些影响的定量理解仍不完整。最近的工作集中在预测进化种群中的适应性分布，这构成了几种方法的基础，这些方法利用适应性分布在强选择时预测遗传多样性模式。然而，在弱选择种群中，由于遗传漂变引起的随机波动更为严重，而且种群内的适应性分布和序列多样性都没有得到很好的理解。在这里，我们简要回顾适应性分布图景背后的动机，并总结在强选择 regime 中用于分析这种分布的一般方法。然后，我们通过概述对大量连锁位点选择的微扰处理，将这些方法扩展到弱选择情况。这使我们能够量化适应性分布的随机行为，并在选择较弱的极限情况下对序列多样性和替代率产生精确的分析预测。
