Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
Nat Ecol Evol. 2020 Mar;4(3):356-365. doi: 10.1038/s41559-020-1121-x. Epub 2020 Feb 24.
What determines the assembly and stability of complex communities is a central question in ecology. Past work has suggested that mutualistic interactions are inherently destabilizing. However, this conclusion relies on the assumption that benefits from mutualisms never stop increasing. Furthermore, almost all theoretical work focuses on the internal (asymptotic) stability of communities assembled all at once. Here, we present a model with saturating benefits from mutualisms and sequentially assembled communities. We show that such communities are internally stable for any level of diversity and any combination of species interaction types. External stability, or resistance to invasion, is thus an important but overlooked measure of stability. We demonstrate that the balance of different interaction types governs community dynamics. A higher fraction of mutualistic interactions can increase the external stability and diversity of communities as well as species persistence, if mutualistic interactions tend to provide unique benefits. Ecological selection increases the prevalence of mutualisms, and limits on biodiversity emerge from species interactions. Our results help resolve long-standing debates on the stability, saturation and diversity of communities.
是什么决定了复杂群落的组装和稳定性是生态学中的一个核心问题。过去的研究表明，互利共生关系本质上是不稳定的。然而，这一结论依赖于一个假设，即互利共生的好处从未停止增加。此外，几乎所有的理论工作都集中在一次性组装的群落的内部（渐近）稳定性上。在这里，我们提出了一个具有互利共生关系饱和收益和顺序组装群落的模型。我们表明，对于任何多样性水平和任何物种相互作用类型的组合，这样的群落在内部都是稳定的。因此，外部稳定性或对入侵的抵抗力是稳定性的一个重要但被忽视的衡量标准。我们证明了不同相互作用类型的平衡控制着群落动态。如果互利共生关系倾向于提供独特的好处，那么更多的互利共生关系可以提高群落的外部稳定性和多样性，以及物种的持久性。生态选择增加了互利共生的普遍性，而生物多样性的限制则来自于物种的相互作用。我们的研究结果有助于解决关于群落的稳定性、饱和和多样性的长期争论。
