The evolution of genomic islands by increased establishment probability of linked alleles
The evolution of genomic islands by increased establishment probability of linked alleles
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DOI：
10.1111/mec.13611
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发表时间：
2016-06-01
影响因子：
4.9
通讯作者：
Buerger, Reinhard
中科院分区：
文献类型：
--
作者：
Yeaman, Sam;Aeschbacher, Simon;Buerger, Reinhard
基因组岛是在种群基因组研究中常见的局部适应和物种形成的具有更高差异性的基因座簇。对它们进化的一种解释是，选定的等位基因之间的联系带来了好处，这增加了与现有的局部适应的多态有关的新突变的建立概率。以前的理论认为，通过这种机制进化岛屿的可能性有限，但涉及一些简化的假设，可能会限制这一推断的准确性。在这里，我们扩展了以前的分析方法来研究连锁对新突变建立概率的影响，并确定最有可能通过这一机制导致岛屿进化的参数机制。我们展示了迁移和选择之间的相互作用如何影响连锁等位基因与非连锁等位基因的建立概率、基因组岛的预期最大大小以及它们进化所需的预期时间。我们的结果与以前的研究一致，表明这一机制本身不太可能成为基因组岛进化的一般解释。然而，如果有其他预适应以降低局部重组速率或增加岛内突变靶标的局部密度，这种机制可能更容易发生。我们还表明，二次接触后通过侵蚀形成的岛屿比从头开始突变形成的岛屿要快得多，这表明这种机制可能更有可能。
Genomic islands are clusters of loci with elevated divergence that are commonly found in population genomic studies of local adaptation and speciation. One explanation for their evolution is that linkage between selected alleles confers a benefit, which increases the establishment probability of new mutations that are linked to existing locally adapted polymorphisms. Previous theory suggested there is only limited potential for the evolution of islands via this mechanism, but involved some simplifying assumptions that may limit the accuracy of this inference. Here, we extend previous analytical approaches to study the effect of linkage on the establishment probability of new mutations and identify parameter regimes that are most likely to lead to evolution of islands via this mechanism. We show how the interplay between migration and selection affects the establishment probability of linked vs. unlinked alleles, the expected maximum size of genomic islands, and the expected time required for their evolution. Our results agree with previous studies, suggesting that this mechanism alone is unlikely to be a general explanation for the evolution of genomic islands. However, this mechanism could occur more readily if there were other pre-adaptations to reduce local rates of recombination or increase the local density of mutational targets within the region of the island. We also show that island formation via erosion following secondary contact is much more rapid than island formation from de novo mutations, suggesting that this mechanism may be more likely.