Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, USA.
Bull Math Biol. 2010 Jul;72(5):1254-70. doi: 10.1007/s11538-009-9489-4. Epub 2010 Feb 5.
Many populations live and disperse in advective media. A fundamental question, known as the "drift paradox" in stream ecology, is how a closed population can survive when it is constantly being transported downstream by the flow. Recent population-level models have focused on the role of diffusive movement in balancing the effects of advection, predicting critical conditions for persistence. Here, we formulate an individual-based stochastic analog of the model described in (Lutscher et al., SIAM Rev. 47(4):749-772, 2005) to quantify the effects of demographic stochasticity on persistence. Population dynamics are modeled as a logistic growth process and dispersal as a position-jump process on a finite domain divided into patches. When there is no correlation in the interpatch movement of residents, stochasticity simply smooths the persistence-extinction boundary. However, when individuals disperse in "packets" from one patch to another and the flow field is memoryless on the timescale of packet transport, the probability of persistence is greatly enhanced. The latter transport mechanism may be characteristic of larval dispersal in the coastal ocean or wind-dispersed seed pods.
许多种群生活和分散在平流介质中。一个基本问题，即在溪流生态学中被称为“漂流悖论”，即当一个封闭的种群被流动不断地向下游输送时，它如何能够生存。最近的种群水平模型集中于扩散运动在平衡平流影响方面的作用，预测了持续存在的关键条件。在这里，我们制定了一个基于个体的随机模拟，模拟了（Lutscher 等人，SIAM Rev. 47(4):749-772, 2005）中描述的模型，以量化人口统计学随机性对持久性的影响。种群动态被建模为逻辑增长过程，扩散被建模为有限域上的位置跳跃过程，该有限域被划分为斑块。当居民在斑块间的运动没有相关性时，随机性只会使持久性-灭绝边界变得平滑。然而，当个体从一个斑块以“包”的形式扩散到另一个斑块，并且流场在包运输的时间尺度上是无记忆的时，持久性的概率会大大提高。后一种传输机制可能是沿海海洋中幼虫扩散或风散种子荚的特征。
