Botany Department, University of Wyoming, Laramie, WY, 82071, USA.
Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, 94720, USA.
Ecol Lett. 2020 Jun;23(6):939-950. doi: 10.1111/ele.13482. Epub 2020 Apr 7.
Coexistence and food web theory are two cornerstones of the long-standing effort to understand how species coexist. Although competition and predation are known to act simultaneously in communities, theory and empirical study of these processes continue to be developed largely independently. Here, we integrate modern coexistence theory and food web theory to simultaneously quantify the relative importance of predation and environmental fluctuations for species coexistence. We first examine coexistence in a theoretical, multitrophic model, adding complexity to the food web using machine learning approaches. We then apply our framework to a stochastic model of the rocky intertidal food web, partitioning empirical coexistence dynamics. We find the main effects of both environmental fluctuations and variation in predator abundances contribute substantially to species coexistence. Unexpectedly, their interaction tends to destabilise coexistence, leading to new insights about the role of bottom-up vs. top-down forces in both theory and the rocky intertidal ecosystem.
共存和食物网理论是理解物种如何共存的长期努力的两个基石。尽管竞争和捕食已知在群落中同时发生，但这些过程的理论和实证研究仍在很大程度上独立进行。在这里，我们整合了现代共存理论和食物网理论，同时定量了捕食和环境波动对物种共存的相对重要性。我们首先在一个理论的、多营养级模型中检验共存，使用机器学习方法为食物网增加复杂性。然后，我们将我们的框架应用于一个 rocky intertidal 食物网的随机模型，对经验共存动态进行划分。我们发现，环境波动和捕食者丰度变化的主要影响都对物种共存有很大贡献。出乎意料的是，它们的相互作用往往会使共存不稳定，从而为理论和 rocky intertidal 生态系统中自上而下和自下而上的力量的作用提供了新的见解。
