Section of Integrative Biology, University of Texas, Austin, TX 78712, USA.
Philos Trans R Soc Lond B Biol Sci. 2012 Feb 5;367(1587):430-8. doi: 10.1098/rstb.2011.0246.
Chromosomal inversions allow genetic divergence of locally adapted populations by reducing recombination between chromosomes with different arrangements. Divergence between populations (or hybridization between species) is expected to leave signatures in the neutral genetic diversity of the inverted region. Quantitative expectations for these patterns, however, have not been obtained. Here, we develop coalescent models of neutral sites linked to an inversion polymorphism in two locally adapted populations. We consider two scenarios of local adaptation: selection on the inversion breakpoints and selection on alleles inside the inversion. We find that ancient inversion polymorphisms cause genetic diversity to depart dramatically from neutral expectations. Other situations, however, lead to patterns that may be difficult to detect; important determinants are the age of the inversion and the rate of gene flux between arrangements. We also study inversions under genetic drift, finding that they produce patterns similar to locally adapted inversions of intermediate age. Our results are consistent with empirical observations, and provide the foundation for quantitative analyses of the roles that inversions have played in speciation.
染色体倒位通过减少具有不同排列的染色体之间的重组，允许局部适应的种群发生遗传分化。种群之间的分化（或物种之间的杂交）预计会在倒位区域的中性遗传多样性中留下特征。然而，对于这些模式的定量预期尚未得到。在这里，我们为两个局部适应种群中与倒位多态性相关的中性位点开发了合并模型。我们考虑了两种局部适应的情况：倒位断点上的选择和倒位内等位基因的选择。我们发现，古老的倒位多态性导致遗传多样性与中性预期显著偏离。然而，其他情况导致的模式可能难以检测；重要的决定因素是倒位的年龄和排列之间基因流动的速度。我们还研究了遗传漂变下的倒位，发现它们产生的模式与中等年龄的局部适应倒位相似。我们的结果与经验观察一致，并为定量分析倒位在物种形成中所起的作用提供了基础。
