California Institute of Technology, USA.
J Theor Biol. 2013 Dec 21;339:84-92. doi: 10.1016/j.jtbi.2013.09.001. Epub 2013 Sep 11.
Simple models of density-dependent population growth such as the discrete logistic map provide powerful demonstrations of complex population dynamics. Yet it is unclear whether the dynamics observed in such idealized systems would be present, under realistic conditions, in the context of demographic stochasticity, which is well known to exist in finite natural populations. Here, using a set of simple, individual-based models (IBM's) and their population-level iterative map counterparts, we computationally investigate the contribution of demographic stochasticity to density-dependent population dynamics in a simple model of seed production and recruitment. Notably, for a sufficiently large lattice, even in the presence of demographic stochasticity, many of the qualitative features of these idealized maps - including bifurcations - are still present. Demographic stochasticity and the constraints imposed by a finite lattice size appear to produce mixed dynamics that are partially stochastic, yet qualitatively similar to the deterministic models. The mechanistic assumptions and lattice sizes required to generate these dynamics cast doubt on whether they might be observable in annual plant populations. Nevertheless, we cannot rule out the theoretical possibility that such dynamics might be observable in ecological communities having similar mechanistic properties.
简单的密度依赖种群增长模型，如离散 logistic 映射，为复杂的种群动态提供了有力的演示。然而，在存在众所周知的有限自然种群中存在的人口统计随机性的现实条件下，这些理想化系统中观察到的动态是否存在尚不清楚。在这里，我们使用一组简单的基于个体的模型（IBM）及其对应的种群水平迭代映射，通过计算来研究在种子生产和招募的简单模型中，人口统计随机性对密度依赖种群动态的贡献。值得注意的是，对于足够大的晶格，即使存在人口统计随机性，这些理想化映射的许多定性特征 - 包括分岔 - 仍然存在。人口统计随机性和有限晶格尺寸的约束似乎产生了部分随机的混合动态，但在定性上与确定性模型相似。产生这些动态所需的机械假设和晶格大小使人们怀疑它们是否可以在一年生植物种群中观察到。然而，我们不能排除这种动态在具有类似机械特性的生态群落中可能被观察到的理论可能性。
