Hu Xin-Sheng
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX13RB, United Kingdom.
Evolution. 2015 May;69(5):1158-77. doi: 10.1111/evo.12660. Epub 2015 May 7.
Understanding mating system as one of reproductive isolating barriers remains important although this barrier is classified in a different sense from behavioral, ecological, and mechanical isolating barriers. Selfing enhances incipient speciation while outcrossing facilitates species integrity. Here, I study how mating system affects gene exchanges between genetically diverging species in a hybrid zone. Results show that a predominant selfing species has a greater barrier to selective gene flow than does a predominant outcrossing species. Barrier to neutral gene flow convexly changes with the selfing rate due to linkage disequilibrium, with a maximum at around intermediate selfing rate. Asymmetric transient or steady-state barriers to neutral gene flow occur between two sides of a hybrid zone when the neutral gene is affected by its linked selective gene whose alternative alleles are adaptive to heterogeneous habitats. Selfing interacts with both a physical barrier and a density-dependent ecological regulation (a logarithmic model) to strengthen the barriers to neutral and selective gene flow. This theory helps to interpret incipient speciation driven by selfing or to explain the asymmetric gene flow or unequal genomic mixtures between closely related species caused by their asymmetric mating systems in natural hybrid zones.
尽管交配系统作为一种生殖隔离屏障与行为、生态和机械隔离屏障的分类意义不同，但理解它仍然很重要。自交促进初始物种形成，而异交则有助于物种完整性。在这里，我研究交配系统如何影响杂交区域中基因分歧物种之间的基因交换。结果表明，与主要进行异交的物种相比，主要进行自交的物种对选择性基因流动具有更大的屏障。由于连锁不平衡，中性基因流动的屏障随着自交率呈凸形变化，在自交率约为中间值时达到最大值。当中性基因受到与其连锁的选择性基因影响，且其替代等位基因适应异质生境时，杂交区域两侧会出现不对称的中性基因流动的瞬态或稳态屏障。自交与物理屏障和密度依赖的生态调节（对数模型）相互作用，以加强对中性和选择性基因流动的屏障。该理论有助于解释由自交驱动的初始物种形成，或解释自然杂交区域中密切相关物种因其不对称交配系统导致的不对称基因流动或不平等基因组混合现象。
