Graduate School of Life Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
Graduate School of Life Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan.
Proc Biol Sci. 2018 May 30;285(1879). doi: 10.1098/rspb.2018.0698.
Ever since May theorized that communities with larger numbers of species or interspecific interactions are inherently unstable, the mechanism allowing for the stable existence of complex communities in nature has been a central question in ecology. The main efforts to answer this question have sought to identify non-random features of ecological systems that can reverse a negative complexity-stability relationship into a positive one, but are far from successful, especially in their generality. Here, using the traditional community matrix analysis, we show that variation in the density dependence of interspecific interactions, which should be ubiquitous in nature, can dramatically affect the complexity-stability relationship. More specifically, we reveal that a positive complexity-stability relationship arises when harmful interspecific effects have larger density dependence than beneficial ones, regardless of the signs (i.e. positive or negative) of their dependence. Furthermore, numerical simulations demonstrated the synergistic stabilizing effect of interaction type diversity and density-dependence variation. Thus, this concept of density-dependence variation advances our understanding of the complexity-stability relationship in the real world.
自 May 提出群落中物种数量或种间相互作用较多的群落本质上不稳定以来，允许复杂群落在自然界中稳定存在的机制一直是生态学的核心问题。为了回答这个问题，主要的努力是试图确定生态系统的非随机特征，这些特征可以将负的复杂性-稳定性关系转变为正的关系，但远未成功，特别是在普遍性方面。在这里，我们使用传统的群落矩阵分析表明，种间相互作用的密度依赖性的变化，这种变化在自然界中应该是普遍存在的，可以显著影响复杂性-稳定性关系。更具体地说，我们揭示了当有害的种间效应比有益的种间效应具有更大的密度依赖性时，就会出现正的复杂性-稳定性关系，而不管它们的依赖性的符号（即正或负）如何。此外，数值模拟表明了相互作用类型多样性和密度依赖性变化的协同稳定效应。因此，这种密度依赖性变化的概念提高了我们对现实世界中复杂性-稳定性关系的理解。
