School of Biology, University of St Andrews, St Andrews, UK.
J Evol Biol. 2013 Feb;26(2):229-46. doi: 10.1111/j.1420-9101.2012.02599.x.
Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near-instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky-Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock-on effects on speciation both within and outside regions of hybridization.
杂交在物种形成过程中有许多不同的影响。杂交可能通过基因流和重组来减缓或逆转分化。它可以通过适应性渗入加速物种形成，也可以通过异源多倍体化导致近瞬时物种形成。它可能在单个物种形成事件的不同阶段和不同的空间背景下产生多种影响。我们提供了一个关于杂交在物种形成过程中的背景和进化意义的视角，强调了当前关注和争论的问题。在次级接触区，由于重组和基因流，基因流动的障碍是加强还是打破还不确定。理论和经验证据表明，后者更有可能，除非在强烈选择的基因组区域内或周围。杂交可能通过形成新的杂交分类群而促进物种形成，而少数基因座的渗入可能促进适应性分歧，从而促进物种形成。基因调控网络、表观遗传效应和基因组中自私遗传物质的进化表明，多布赞斯基-穆勒模型的杂种不兼容性需要更广泛的解释。最后，尽管强化的发生率仍不确定，但同域区的这种和其他相互作用可能对杂交区内外的物种形成产生连锁效应。
