Gallien Laure, Zimmermann Niklaus E, Levine Jonathan M, Adler Peter B
Swiss Federal Research Institute WSL, Birmensdorf, 8903, Switzerland.
Deparment of Botany & Zoology, Centre for Invasion Biology, Stellenbosch University, Matieland, 7602, South Africa.
Ecol Lett. 2017 Jul;20(7):791-800. doi: 10.1111/ele.12775. Epub 2017 May 26.
Coexistence theory has been developed with an almost exclusive focus on interactions between two species, often ignoring more complex and indirect interactions, such as intransitive loops, that can emerge in competition networks. In fact, intransitive competition has typically been studied in isolation from other pairwise stabilising processes, and thus little is known about how intransitivity interacts with more traditional drivers of species coexistence such as niche partitioning. To integrate intransitivity into traditional coexistence theory, we developed a metric of growth rate when rare, Δri¯, to identify and quantify the impact of intransitive competition against a backdrop of pairwise stabilising niche differences. Using this index with simulations of community dynamics, we demonstrate that intransitive loops can both stabilise or destabilise species coexistence, but the strength and importance of intransitive interactions are significantly affected by the length and the topology of these loops. We conclude by showing how Δri¯ can be used to evaluate effects of intransitivity in empirical studies. Our results emphasise the need to integrate complex mechanisms emerging from diverse interactions into our understanding of species coexistence.
共存理论的发展几乎完全聚焦于两个物种之间的相互作用，常常忽略了竞争网络中可能出现的更复杂、更间接的相互作用，例如非传递性循环。事实上，非传递性竞争通常是与其他成对稳定过程分开进行研究的，因此对于非传递性如何与物种共存的更传统驱动因素（如生态位划分）相互作用，我们知之甚少。为了将非传递性纳入传统的共存理论，我们开发了一个稀有状态下的增长率指标Δri¯，以识别和量化在成对稳定的生态位差异背景下非传递性竞争的影响。通过将这个指标用于群落动态模拟，我们证明非传递性循环既可以稳定也可以破坏物种共存，但非传递性相互作用的强度和重要性会受到这些循环的长度和拓扑结构的显著影响。我们通过展示如何使用Δri¯来评估实证研究中非传递性的影响来得出结论。我们的结果强调了将多种相互作用产生的复杂机制纳入我们对物种共存理解的必要性。
