One strand of modern coexistence theory (MCT) partitions invader growth rates (IGR) to quantify how different mechanisms contribute to species coexistence, highlighting fluctuation‐dependent mechanisms. A general conclusion from the classical analytic MCT theory is that coexistence mechanisms relying on temporal variation (such as the temporal storage effect) are generally less effective at promoting coexistence than mechanisms relying on spatial or spatiotemporal variation (primarily growth‐density covariance). However, the analytic theory assumes continuous population density, and IGRs are calculated for infinitesimally rare invaders that have infinite time to find their preferred habitat and regrow, without ever experiencing intraspecific competition. Here we ask if the disparity between spatial and temporal mechanisms persists when individuals are, instead, discrete and occupy finite amounts of space. We present a simulation‐based approach to quantifying IGRs in this situation, building on our previous approach for spatially non‐varying habitats. As expected, we found that spatial mechanisms are weakened; unexpectedly, the contribution to IGR from growth‐density covariance could even become negative, opposing coexistence. We also found shifts in which demographic parameters had the largest effect on the strength of spatial coexistence mechanisms. Our substantive conclusions are statements about one model, across parameter ranges that we subjectively considered realistic. Using the methods developed here, effects of individual discreteness should be explored theoretically across a broader range of conditions, and in models parameterized from empirical data on real communities.

中文翻译：

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这是关于（占用）空间：个体的离散性和空间共存机制的力量


现代共存理论 （MCT） 的一个分支划分入侵者生长速率 （IGR） 以量化不同机制如何促进物种共存，突出波动依赖机制。经典分析 MCT 理论的一般结论是，依赖于时间变化的共存机制（例如时间存储效应）在促进共存方面通常不如依赖于空间或时空变化（主要是增长-密度协方差）的机制有效。然而，分析理论假设连续的种群密度，IGR 是针对极小稀有的入侵者计算的，这些入侵者有无限的时间来找到它们喜欢的栖息地并重新生长，而从未经历过种内竞争。在这里，我们要问的是，当个体是离散的并且占据有限的空间时，空间和时间机制之间的差异是否仍然存在。我们提出了一种基于模拟的方法来量化在这种情况下的 IGR，以我们之前针对空间不变栖息地的方法为基础。正如预期的那样，我们发现空间机制被削弱了;出乎意料的是，生长密度协方差对 IGR 的贡献甚至可能变为负值，与共存相反。我们还发现了人口统计参数对空间共存机制强度影响最大的变化。我们的实质性结论是关于一个模型的陈述，跨越我们主观认为现实的参数范围。使用这里开发的方法，应该在更广泛的条件下从理论上探索个体离散性的影响，并在根据真实社区的经验数据参数化的模型中进行探索。