Theoretical Ecology Group, Department of Mathematical Sciences, Stellenbosch University, Matieland, 7602, South Africa.
Department of Ecology and Evolution, University of Lausanne, Lausanne, 1015, Switzerland.
Evolution. 2018 Sep;72(9):1784-1800. doi: 10.1111/evo.13562. Epub 2018 Aug 20.
Despite empirical evidence for a positive relationship between dispersal and self-fertilization (selfing), theoretical work predicts that these traits should always be negatively correlated, and the Good Coloniser Syndrome of high dispersal and selfing (Cf. Baker's Law) should not evolve. Critically, previous work assumes that adult density is spatiotemporally homogeneous, so selfing results in identical offspring production for all patches, eliminating the benefit of dispersal for escaping from local resource competition. We investigate the joint evolution of dispersal and selfing in a demographically structured metapopulation model where local density is spatiotemporally heterogeneous due to extinction-recolonization dynamics. Selfing alleviates outcrossing failure due to low local density (an Allee effect) while dispersal alleviates competition through dispersal of propagules from high- to low-density patches. Because local density is spatiotemporally heterogeneous in our model, selfing does not eliminate heterogeneity in competition, so dispersal remains beneficial even under full selfing. Hence the Good Coloniser Syndrome is evolutionarily stable under a broad range of conditions, and both negative and positive relationships between dispersal and selfing are possible, depending on the environment. Our model thus accommodates positive empirical relationships between dispersal and selfing not predicted by previous theoretical work and provides additional explanations for negative relationships.
尽管有实证证据表明扩散和自交（自花授粉）之间存在正相关关系，但理论工作预测这些特征应该始终呈负相关，并且高扩散和自交的“好殖民者综合征”（参见贝克定律）不应进化。关键是，以前的工作假设成年密度在时空上是均匀的，因此自交导致所有斑块的后代产生相同，从而消除了通过扩散逃避局部资源竞争的好处。我们在一个具有扩散和自交的人口结构的复合种群模型中研究了它们的联合进化，其中由于灭绝再定居动态，局部密度在时空上是不均匀的。自交减轻了由于局部密度低而导致的异交失败（阿利效应），而扩散则通过将繁殖体从高密度斑块扩散到低密度斑块来减轻竞争。由于我们的模型中的局部密度在时空上是不均匀的，自交不会消除竞争中的异质性，因此即使在完全自交的情况下，扩散仍然是有益的。因此，在广泛的条件下，好殖民者综合征是进化稳定的，扩散和自交之间可能存在负相关和正相关关系，这取决于环境。因此，我们的模型可以解释以前的理论工作无法预测的扩散和自交之间的正相关关系，并为负相关关系提供额外的解释。
