Dispersal increases ecological selection by increasing effective community size.
Dispersal increases ecological selection by increasing effective community size.
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DOI：
10.1073/pnas.1812511115
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发表时间：
2018-10-30
影响因子：
11.1
通讯作者：
Kadmon R
中科院分区：
文献类型：
--
作者：
Ron R;Fragman-Sapir O;Kadmon R
生态学的一个基本挑战是了解生态群落组成变化的机制。在最基本的层面上，物种组成的任何变化都是两种对立力量之间相互作用的结果：选择（代表确定性力量）和漂移（代表随机性力量）。在这里，我们提供的实验证据表明，这两种力量的相对重要性取决于分散的大小。具体而言，增加分散增加了社区的有效规模，从而降低了人口随机性的相对重要性，并增加了选择性力量作为社区集会驱动力的相对重要性。我们的研究结果得到了计算机模拟的支持，对于理解扩散的生态后果具有重要意义。选择和漂变被普遍认为是进化变化的基石。最近的理论将这一观点扩展到生态变化，认为物种组成的任何变化都是由物种之间的确定性适合度差异（增强选择）和/或物种内个体出生和死亡率的随机性（增强漂移）驱动的。这些力量对生态动力学的可预测性有着截然不同的影响，因此了解影响其相对重要性的因素对于理解生态动力学至关重要。在这里，我们测试的假设，扩散增加了生态选择的相对重要性，通过增加社区的有效规模（即，与竞争相互作用和漂移相关的大小）。根据我们的假设，扩散通过混合来自不同地点的个体来增加群落的有效规模。这种效应降低了人口统计随机性的相对重要性，从而减少了漂移，增加了选择力作为物种组成驱动因素的相对重要性。我们测试了我们的假设，我们称之为“有效的社区规模”的假设，使用两个独立的实验专注于一年生植物：一个现场实验中，我们操纵的规模的扩散和一个中围实验中，我们直接操纵的社区的有效规模。这两个实验，以及相关的模型模拟，是一致的假设，即增加扩散增加的选择力的作用，物种组成的驱动程序。这一发现对我们理解影响群落动态的基本力量以及物种多样性的管理具有重要意义，特别是在斑块和碎片化的环境中。
A basic challenge of ecology is to understand the mechanisms that generate changes in the composition of ecological communities. At the most fundamental level, any change in species composition results from the interplay between two contrasting forces: selection (representing deterministic forces) and drift (representing stochastic forces). Here we provide experimental evidence that the relative importance of these two forces depends on the magnitude of dispersal. Specifically, increasing dispersal increases the effective size of the communities, thereby diminishing the relative importance of demographic stochasticity and increasing the relative importance of selective forces as drivers of community assembly. Our findings, supported by computer simulations, have important implications for understanding the ecological consequences of dispersal. Selection and drift are universally accepted as the cornerstones of evolutionary changes. Recent theories extend this view to ecological changes, arguing that any change in species composition is driven by deterministic fitness differences among species (enhancing selection) and/or stochasticity in birth and death rates of individuals within species (enhancing drift). These forces have contrasting effects on the predictability of ecological dynamics, and thus understanding the factors affecting their relative importance is crucial for understanding ecological dynamics. Here we test the hypothesis that dispersal increases the relative importance of ecological selection by increasing the effective size of the community (i.e., the size relevant for competitive interactions and drift). According to our hypothesis, dispersal increases the effective size of the community by mixing individuals from different localities. This effect diminishes the relative importance of demographic stochasticity, thereby reducing drift and increasing the relative importance of selective forces as drivers of species composition. We tested our hypothesis, which we term the “effective community size” hypothesis, using two independent experiments focusing on annual plants: a field experiment in which we manipulated the magnitude of dispersal and a mesocosm experiment in which we directly manipulated the effective size of the communities. Both experiments, as well as related model simulations, were consistent with the hypothesis that increasing dispersal increases the role of selective forces as drivers of species composition. This finding has important implications for our understanding of the fundamental forces affecting community dynamics, as well as the management of species diversity, particularly in patchy and fragmented environments.
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