Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
Philos Trans R Soc Lond B Biol Sci. 2012 Feb 5;367(1587):461-74. doi: 10.1098/rstb.2011.0256.
Theoretical models addressing genome-wide patterns of divergence during speciation are needed to help us understand the evolutionary processes generating empirical patterns. Here, we examine a critical issue concerning speciation-with-gene flow: to what degree does physical linkage (r < 0.5) of new mutations to already diverged genes aid the build-up of genomic islands of differentiation? We used simulation and analytical approaches to partition the probability of establishment for a new divergently selected mutation when the mutation (i) is the first to arise in an undifferentiated genome (the direct effect of selection), (ii) arises unlinked to any selected loci (r = 0.5), but within a genome that has some already diverged genes (the effect of genome-wide reductions in gene flow for facilitating divergence, which we term 'genome hitchhiking'), and (iii) arises in physical linkage to a diverged locus (divergence hitchhiking). We find that the strength of selection acting directly on a new mutation is generally the most important predictor for establishment, with divergence and genomic hitchhiking having smaller effects. We outline the specific conditions under which divergence and genome hitchhiking can aid mutation establishment. The results generate predictions about genome divergence at different points in the speciation process and avenues for further work.
需要理论模型来解决物种形成过程中基因组范围的分歧模式，以帮助我们理解产生经验模式的进化过程。在这里，我们研究了一个关于有基因流动的物种形成的关键问题：新突变与已经分化的基因之间的物理连锁（r < 0.5）在多大程度上有助于形成基因组分化岛？我们使用模拟和分析方法来划分新的分歧选择突变建立的概率，当突变（i）首次出现在未分化的基因组中（选择的直接影响），（ii）与任何选择的基因座没有关联（r = 0.5），但在已经有一些分化的基因的基因组中（促进分歧的全基因组降低基因流的影响，我们称之为“基因组搭便车”），和（iii）与分化的基因座物理连锁（分化搭便车）。我们发现，新突变直接受到选择的强度通常是建立的最重要预测因素，而分歧和基因组搭便车的影响较小。我们概述了分歧和基因组搭便车可以帮助突变建立的具体条件。研究结果对物种形成过程中不同阶段的基因组分歧以及进一步工作的途径产生了预测。
