Institut für Populationsgenetik, Vetmeduni Vienna, 1210 Vienna, Austria.
Genetics. 2012 Jul;191(3):845-63. doi: 10.1534/genetics.111.137513. Epub 2012 Apr 27.
How much gene flow is needed to inhibit speciation by the accumulation of Dobzhansky-Muller incompatibilities (DMIs) in a structured population? Here, we derive these limits in a classical migration-selection model with two haploid or diploid loci and unidirectional gene flow from a continent to an island. We discuss the dependence of the maximum gene-flow rate on ecological factors (exogeneous selection), genetic factors (epistasis, recombination), and the evolutionary history. Extensive analytical and numerical results show the following: (1) The maximum rate of gene flow is limited by exogeneous selection. In particular, maintenance of neutral DMIs is impossible with gene flow. (2) There are two distinct mechanisms that drive DMI evolution in parapatry, selection against immigrants in a heterogeneous environment and selection against hybrids due to the incompatibility. (3) Depending on the mechanism, opposite predictions result concerning the genetic architecture that maximizes the rate of gene flow a DMI can sustain. Selection against immigrants favors evolution of tightly linked DMIs of arbitrary strength, whereas selection against hybrids promotes the evolution of strong unlinked DMIs. In diploids, the fitness of the double heterozygotes is the decisive factor to predict the pattern of DMI stability.
需要多少基因流才能抑制由 Dobzhansky-Muller 不相容性（DMIs）积累引起的物种形成？在这里，我们在一个具有两个单倍体或二倍体基因座和从大陆到岛屿单向基因流的经典迁移选择模型中推导出这些限制。我们讨论了最大基因流动率对生态因素（外生选择）、遗传因素（上位性、重组）和进化历史的依赖关系。广泛的分析和数值结果表明：（1）最大基因流动率受外生选择限制。特别是，中性 DMIs 的维持不可能有基因流。（2）在邻域中存在两种截然不同的驱动 DMI 进化的机制，即对异质环境中移民的选择和由于不相容性对杂种的选择。（3）根据机制的不同，对于能够维持最大基因流动率的 DMI 的遗传结构，会产生相反的预测。对移民的选择有利于紧密连锁的任意强度 DMIs 的进化，而对杂种的选择则促进了强非连锁 DMIs 的进化。在二倍体中，双杂合体的适应性是预测 DMI 稳定性模式的决定性因素。
