Feder Jeffrey L, Nosil Patrik, Wacholder Aaron C, Egan Scott P, Berlocher Stewart H, Flaxman Samuel M
From the Department of Biological Science, Environmental Change Initiative, and Advanced Diagnostics and Therapeutics, University of Notre Dame, Notre Dame, IN 46556 (Feder); the Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S102TN (Nosil); the Interdisciplinary Quantitative Biology Program, University of Colorado, Boulder, CO 80309 (Wacholder); the Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005 (Egan); the Department of Entomology, University of Illinois, Urbana, IL 61801 (Berlocher); and the Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309 (Flaxman).
J Hered. 2014;105 Suppl 1:810-20. doi: 10.1093/jhered/esu038.
Our current understanding of speciation is often based on considering a relatively small number of genes, sometimes in isolation of one another. Here, we describe a possible emergent genome process involving the aggregate effect of many genes contributing to the evolution of reproductive isolation across the speciation continuum. When a threshold number of divergently selected mutations of modest to low fitness effects accumulate between populations diverging with gene flow, nonlinear transitions can occur in which levels of adaptive differentiation, linkage disequilibrium, and reproductive isolation dramatically increase. In effect, the genomes of the populations start to "congeal" into distinct entities representing different species. At this stage, reproductive isolation changes from being a characteristic of specific, divergently selected genes to a property of the genome. We examine conditions conducive to such genome-wide congealing (GWC), describe how to empirically test for GWC, and highlight a putative empirical example involving Rhagoletis fruit flies. We conclude with cautious optimism that the models and concepts discussed here, once extended to large numbers of neutral markers, may provide a framework for integrating information from genome scans, selection experiments, quantitative trait loci mapping, association studies, and natural history to develop a deeper understanding of the genomics of speciation.
我们目前对物种形成的理解通常基于对相对较少数量基因的研究，有时这些基因是彼此孤立考虑的。在此，我们描述了一种可能的新兴基因组过程，该过程涉及许多基因的综合效应，这些基因有助于在物种形成连续统中生殖隔离的进化。当在具有基因流的分化种群之间积累了阈值数量的具有适度至低适应性效应的分歧选择突变时，就会发生非线性转变，其中适应性分化、连锁不平衡和生殖隔离水平会急剧增加。实际上，种群的基因组开始“凝固”成代表不同物种的不同实体。在这个阶段，生殖隔离从特定的、分歧选择基因的特征转变为基因组的一种属性。我们研究有利于这种全基因组凝固（GWC）的条件，描述如何通过实证检验GWC，并突出一个涉及山楂实蝇的假定实证例子。我们带着谨慎的乐观态度得出结论，这里讨论的模型和概念一旦扩展到大量中性标记，可能会提供一个框架，用于整合来自基因组扫描、选择实验、数量性状基因座定位、关联研究和自然史的信息，以更深入地理解物种形成的基因组学。
