Department of Physics, Boston University, Boston, Massachusetts 02215, USA.
Phys Rev E. 2016 Aug;94(2-1):022423. doi: 10.1103/PhysRevE.94.022423. Epub 2016 Aug 30.
A fundamental problem in community ecology is understanding how ecological processes such as selection, drift, and immigration give rise to observed patterns in species composition and diversity. Here, we analyze a recently introduced, analytically tractable, presence-absence (PA) model for community assembly, and we use it to ask how ecological traits such as the strength of competition, the amount of diversity, and demographic and environmental stochasticity affect species composition in a community. In the PA model, species are treated as stochastic binary variables that can either be present or absent in a community: species can immigrate into the community from a regional species pool and can go extinct due to competition and stochasticity. Building upon previous work, we show that, despite its simplicity, the PA model reproduces the qualitative features of more complicated models of community assembly. In agreement with recent studies of large, competitive Lotka-Volterra systems, the PA model exhibits distinct ecological behaviors organized around a special ("critical") point corresponding to Hubbell's neutral theory of biodiversity. These results suggest that the concepts of ecological "phases" and phase diagrams can provide a powerful framework for thinking about community ecology, and that the PA model captures the essential ecological dynamics of community assembly.
群落生态学的一个基本问题是理解生态过程（如选择、漂变和迁入）如何导致物种组成和多样性的观测模式。在这里，我们分析了一种最近提出的、可分析的、存在-不存在（PA）群落组装模型，并利用它来研究生态特征（如竞争强度、多样性程度、以及种群和环境随机性）如何影响群落中的物种组成。在 PA 模型中，物种被视为随机的二值变量，可以存在于群落中，也可以不存在：物种可以从区域物种库中迁入群落，并由于竞争和随机性而灭绝。在先前工作的基础上，我们表明，尽管该模型简单，但它再现了群落组装更复杂模型的定性特征。与最近对大型竞争 Lotka-Volterra 系统的研究一致，PA 模型表现出围绕对应于 Hubbell 中性生物多样性理论的特殊（“临界”）点的独特生态行为。这些结果表明，生态“相”和相图的概念可以为思考群落生态学提供一个强大的框架，并且 PA 模型捕捉到了群落组装的基本生态动态。
