Pannell John R
Department of Ecology and Evolution, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland.
Mol Ecol. 2015 May;24(9):2018-37. doi: 10.1111/mec.13087. Epub 2015 Mar 6.
Colonization is likely to be more successful for species with an ability to self-fertilize and thus to establish new populations as single individuals. As a result, self-compatibility should be common among colonizing species. This idea, labelled 'Baker's law', has been influential in discussions of sexual-system and mating-system evolution. However, its generality has been questioned, because models of the evolution of dispersal and the mating system predict an association between high dispersal rates and outcrossing rather than selfing, and because of many apparent counter examples to the law. The contrasting predictions made by models invoking Baker's law versus those for the evolution of the mating system and dispersal urges a reassessment of how we should view both these traits. Here, I review the literature on the evolution of mating and dispersal in colonizing species, with a focus on conceptual issues. I argue for the importance of distinguishing between the selfing or outcrossing rate and a simple ability to self-fertilize, as well as for the need for a more nuanced consideration of dispersal. Colonizing species will be characterized by different phases in their life pattern: dispersal to new habitat, implying an ecological sieve on dispersal traits; establishment and a phase of growth following colonization, implying a sieve on reproductive traits; and a phase of demographic stasis at high density, during which new trait associations can evolve through local adaptation. This dynamic means that the sorting of mating-system and dispersal traits should change over time, making simple predictions difficult.
对于具有自花受精能力从而能够以单个个体形式建立新种群的物种来说，定殖可能会更成功。因此，自交亲和性在定殖物种中应该很常见。这一观点被称为“贝克法则”，在关于性系统和交配系统进化的讨论中颇具影响力。然而，其普遍性受到了质疑，因为扩散和交配系统进化模型预测高扩散率与异交而非自交之间存在关联，也因为该法则存在许多明显的反例。援引贝克法则的模型与交配系统和扩散进化模型所做出的不同预测促使我们重新审视应如何看待这两个性状。在此，我回顾了关于定殖物种交配和扩散进化的文献，重点关注概念性问题。我认为区分自交或异交率与简单的自花受精能力很重要，同时也需要对扩散进行更细致入微的考量。定殖物种在其生活模式中会有不同阶段：扩散到新栖息地，这意味着对扩散性状进行生态筛选；定殖以及定殖后的生长阶段，这意味着对生殖性状进行筛选；以及在高密度下的种群数量稳定阶段，在此期间新的性状关联可通过局部适应而进化。这种动态变化意味着交配系统和扩散性状的筛选会随时间而改变，从而难以做出简单预测。
