Institute of Zoology, Regent's Park, London, UK.
Ecol Lett. 2010 Apr;13(4):485-94. doi: 10.1111/j.1461-0248.2010.01442.x.
All species are restricted in their distribution. Currently, ecological models can only explain such limits if patches vary in quality, leading to asymmetrical dispersal, or if genetic variation is too low at the margins for adaptation. However, population genetic models suggest that the increase in genetic variance resulting from dispersal should allow adaptation to almost any ecological gradient. Clearly therefore, these models miss something that prevents evolution in natural populations. We developed an individual-based simulation to explore stochastic effects in these models. At high carrying capacities, our simulations largely agree with deterministic predictions. However, when carrying capacity is low, the population fails to establish for a wide range of parameter values where adaptation was expected from previous models. Stochastic or transient effects appear critical around the boundaries in parameter space between simulation behaviours. Dispersal, gradient steepness, and population density emerge as key factors determining adaptation on an ecological gradient.
所有物种的分布都受到限制。目前，如果斑块在质量上存在差异，导致扩散不对称，或者在边缘的遗传变异太低，无法适应，生态模型只能解释这种限制。然而，种群遗传模型表明，扩散导致的遗传方差增加应该允许适应几乎任何生态梯度。显然，这些模型忽略了阻止自然种群进化的某些因素。我们开发了一个基于个体的模拟来探索这些模型中的随机效应。在高承载能力下，我们的模拟与确定性预测基本一致。然而，当承载能力较低时，种群无法在之前模型预期适应的广泛参数值范围内建立。在模拟行为之间的参数空间边界处，随机或瞬态效应似乎至关重要。扩散、梯度陡度和种群密度成为决定生态梯度上适应性的关键因素。
