Dispersal is one of the most important drivers of community assembly. Understanding how dispersal impacts spatial variations in community composition (beta diversity) is crucial for predicting biodiversity change during the Anthropocene. Classic theories and a large amount of empirical evidence have led to a common belief that increasing dispersal rate should lead to regional community homogenization (lower beta diversity). However, recent empirical studies show that increasing dispersal can also lead to regional community divergence when interacting with other processes such as disturbance and priority effect. The underappreciation of the complex relationship between beta diversity and dispersal might impede our ability to make accurate ecological forecasts. To address this concern, I examine the beta diversity–dispersal relationship through extinction and colonization dynamics in meta-community models. I find that a wide range of beta diversity–dispersal relationships (e.g. negative, positive, hump-shaped) can be generated by changes in species-level occurrence probabilities when meta-population dispersal (rather than mainland–island dispersal), disturbance and strong biotic interactions are at play. Specifically, reducing the variance of species-level occurrence probabilities leads to community divergence and increasing the mean occurrence probability leads to community homogenization; a positive or hump-shaped beta diversity–dispersal relationship emerges when the effect of the decreasing variance is stronger than the effect of increasing mean. These findings highlight the intrinsic constraint of occupancy stochasticity on beta diversity changes and echo the call for more realistic manipulations of stochastic dispersal and a detailed understanding of the interaction networks to test various beta diversity–dispersal relationships in future empirical studies.

中文翻译：

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元社区模型中β多样性与分散之间的复杂关系

分散是社区集会最重要的驱动因素之一。了解散布如何影响群落组成（β 多样性）的空间变化对于预测人类世期间的生物多样性变化至关重要。经典理论和大量经验证据导致普遍认为，增加扩散率应该导致区域群落同质化（较低的贝塔多样性）。然而，最近的实证研究表明，在与干扰和优先效应等其他过程相互作用时，不断增加的分散也会导致区域社区分化。对 Beta 多样性与扩散之间复杂关系的低估可能会阻碍我们做出准确生态预测的能力。为了解决这个问题，我通过元社区模型中的灭绝和殖民动态研究了 Beta 多样性-扩散关系。我发现当元种群扩散（而不是大陆-岛屿扩散）、干扰和强生物相互作用在起作用。具体来说，降低物种水平发生概率的方差导致群落分化，增加平均发生概率导致群落同质化；当方差减少的影响强于均值增加的影响时，就会出现正的或驼峰形的 Beta 多样性-扩散关系。