Despite the well known scale-dependency of ecological interactions, relatively little attention has been paid to understanding the dynamic interplay between various spatial scales. This is especially notable in metacommunity theory, where births and deaths dominate dynamics within patches (the local scale), and dispersal and environmental stochasticity dominate dynamics between patches (the regional scale). By considering the interplay of local and regional scales in metacommunities, the fundamental processes of community ecology—selection, drift, and dispersal—can be unified into a single theoretical framework. Here, we analyze three related spatial models that build on the classic two-species Lotka–Volterra competition model. Two open-system models focus on a single patch coupled to a larger fixed landscape by dispersal. The first is deterministic, while the second adds demographic stochasticity to allow ecological drift. Finally, the third model is a true metacommunity model with dispersal between a large number of local patches, which allows feedback between local and regional scales and captures the well studied metacommunity paradigms as special cases. Unlike previous simulation models, our metacommunity model allows the numerical calculation of equilibria and invasion criteria to precisely determine the outcome of competition at the regional scale. We show that both dispersal and stochasticity can lead to regional outcomes that are different than predicted by the classic Lotka–Volterra competition model. Regional exclusion can occur when the nonspatial model predicts coexistence or founder control, due to ecological drift or asymmetric stochastic switching between basins of attraction, respectively. Regional coexistence can result from local coexistence mechanisms or through competition-colonization or successional-niche trade-offs. Larger dispersal rates are typically competitively advantageous, except in the case of local founder control, which can favor intermediate dispersal rates. Broadly, our models demonstrate the importance of feedback between local and regional scales in competitive metacommunities and provide a unifying framework for understanding how selection, drift, and dispersal jointly shape ecological communities.

中文翻译：

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将地方和区域尺度与随机元社区模型联系起来：竞争、生态漂移和扩散

尽管生态相互作用具有众所周知的尺度依赖性，但人们对理解不同空间尺度之间的动态相互作用的关注相对较少。这在元群落理论中尤其值得注意，其中出生和死亡主导斑块内（局部尺度）的动态，而扩散和环境随机性主导斑块之间（区域尺度）的动态。通过考虑元群落中地方和区域尺度的相互作用，群落生态学的基本过程——选择、漂移和扩散——可以统一到一个单一的理论框架中。在这里，我们分析了建立在经典的两物种 Lotka-Volterra 竞争模型基础上的三个相关空间模型。两个开放系统模型专注于通过分散与更大的固定景观耦合的单个斑块。第一个是确定性的，而第二个则增加了人口随机性以允许生态漂移。最后，第三个模型是真正的元社区模型，分散在大量局部斑块之间，允许局部和区域尺度之间的反馈，并将经过充分研究的元社区范式捕获为特殊情况。与以前的模拟模型不同，我们的元社区模型允许对平衡和入侵标准进行数值计算，以精确确定区域尺度的竞争结果。我们表明，分散性和随机性都会导致区域结果与经典 Lotka-Volterra 竞争模型的预测不同。当非空间模型预测共存或创始人控制时，可能会发生区域排斥，分别是由于生态漂移或吸引力盆地之间的不对称随机切换。区域共存可以通过当地共存机制或通过竞争殖民或继承利基权衡来实现。较大的分散率通常具有竞争优势，但本地创始人控制的情况除外，这可能有利于中等分散率。从广义上讲，我们的模型证明了竞争性元群落中地方和区域尺度之间反馈的重要性，并为理解选择、漂移和扩散如何共同塑造生态群落提供了一个统一的框架。