School of Biology, University of Leeds, Leeds, United Kingdom.
PLoS One. 2013 Jul 16;8(7):e67871. doi: 10.1371/journal.pone.0067871. Print 2013.
Two important issues for conservation are the range expansion of species as a result of climate change and the invasion of exotic species. Being able to predict the rate at which species spread is key for successful management. In deterministic models, the invasion speed of a polymorphic population can be faster than that of any of the component phenotypes, and these "anomalous" invasion speeds persist even when the mutation rate between phenotypes is vanishingly small. Here we investigate whether the same phenomenon is observed in a model with demographic stochasticity. The model that we use is discrete in time and space and we carry out numerical simulations to determine the invasion speed of a population that has two morphs which differ in their dispersal abilities. We find that anomalous speeds are observed in the stochastic model, but only when the carrying capacity of the population is large or the mutation rate between morphs is high enough. These results suggest that only species with large population sizes, such as many insect species, may be able to invade faster if they are polymorphic than if there is only a single morph present in the population.
保护面临两个重要问题，一是物种因气候变化而范围扩大，二是外来物种入侵。能够预测物种传播的速度是成功管理的关键。在确定性模型中，多态种群的入侵速度可能比任何组成表型都快，即使表型之间的突变率极小，这些“异常”的入侵速度仍然存在。在这里，我们研究了在具有人口统计学随机性的模型中是否观察到相同的现象。我们使用的模型在时间和空间上是离散的，我们进行数值模拟来确定具有两种在扩散能力上存在差异的形态的种群的入侵速度。我们发现，在随机模型中观察到了异常速度，但只有当种群的承载能力较大或形态之间的突变率足够高时才会出现这种情况。这些结果表明，只有具有较大种群规模的物种（例如许多昆虫物种）如果是多态的，那么它们的入侵速度可能会比种群中只有一种形态存在时更快。
