Interaction Dimensionality Scales Up to Generate Bimodal Consumer-Resource Size-Ratio Distributions in Ecological Communities
Interaction Dimensionality Scales Up to Generate Bimodal Consumer-Resource Size-Ratio Distributions in Ecological Communities
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DOI：
10.3389/fevo.2019.00202
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发表时间：
2019-06-12
影响因子：
3
通讯作者：
Savage, Van M.
中科院分区：
文献类型：
--
作者：
Pawar, Samraat;Dell, Anthony, I;Savage, Van M.
从生态和进化的角度来看，了解消费者资源体型比例的限制至关重要。通过分析来自九个生态群落的 4,685 个消费者-资源相互作用的数据，我们表明，在空间复杂的环境中——消费者可以在两个（2D，例如海底区域）和三个（3D，例如远洋区域）空间维度中觅食——资源与消费者的体型比分布趋于双峰，具有不同的中值 2D 和 3D 峰值。具体来说，我们发现在社区内部和社区之间，3D 中的中值尺寸比始终小于 2D 中的尺寸比。此外，任何群落内的 2D 和 3D 尺寸（不是尺寸比率）分布在统计上通常无法区分，这表明尺寸比率的双峰性并不是简单地由维度上物种的先验尺寸隔离（以及因此相互作用）驱动，而是由于其他因素。我们开发的理论可以正确预测 2D 和 3D 尺寸比分布之间的这些差异的方向和大小。我们的理论表明，群落级尺寸比率双峰性源于 3D 交互中比 2D 交互中消费率随尺寸更强的缩放，这既最大化了消费者的适应性，又允许在 3D 中更大范围的尺寸比率中共存。我们还发现，消费者的张开限制可以放大 2D 和 3D 尺寸比之间的差异，并且对于任一维度，更高的承载能力允许更广泛的尺寸比共存。我们的结果揭示了对生态群落规模结构的新的普遍见解，并表明环境的空间复杂性可以对跨组织规模的群落结构和动态产生深远的影响。
Understanding constraints on consumer-resource body size-ratios is fundamentally important from both ecological and evolutionary perspectives. By analyzing data on 4,685 consumer-resource interactions from nine ecological communities, we show that in spatially complex environments-where consumers can forage in both two (2D, e. g., benthic zones) and three (3D, e. g., pelagic zones) spatial dimensions-the resource-to-consumer body size-ratio distribution tends toward bimodality, with different median 2D and 3D peaks. Specifically, we find that median size-ratio in 3D is consistently smaller than in 2D both within and across communities. Furthermore, 2D and 3D size (not size-ratio) distributions within any community are generally indistinguishable statistically, indicating that the bimodality in size-ratios is not driven simply by a priori size-segregation of species (and therefore, interactions) by dimensionality, but due to other factors. We develop theory that correctly predicts the direction and magnitude of these differences between 2D and 3D size-ratio distributions. Our theory suggests that community-level size-ratio bimodality emerges from the stronger scaling of consumption rate with size in 3D interactions than in 2D which both, maximizes consumer fitness, and allows coexistence, across a larger range of size-ratios in 3D. We also find that consumer gape-limitation can amplify differences between 2D and 3D size-ratios, and that for either dimensionality, higher carrying capacity allows coexistence of a wider range of size-ratios. Our results reveal new and general insights into the size structure of ecological communities, and show that spatial complexity of the environment can have far reaching effects on community structure and dynamics across scales of organization.