Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel.
PLoS Comput Biol. 2020 Oct 12;16(10):e1008189. doi: 10.1371/journal.pcbi.1008189. eCollection 2020 Oct.
We show how highly-diverse ecological communities may display persistent abundance fluctuations, when interacting through resource competition and subjected to migration from a species pool. These fluctuations appear, robustly and predictably, in certain regimes of parameter space. Their origin is closely tied to the ratio of realized species diversity to the number of resources. This ratio is set by competition, through the balance between species being pushed out and invading. When this ratio is smaller than one, dynamics will reach stable equilibria. When this ratio is larger than one, the competitive exclusion principle dictates that fixed-points are either unstable or marginally stable. If they are unstable, the system is repelled from fixed points, and abundances forever fluctuate. While marginally-stable fixed points are in principle allowed and predicted by some models, they become structurally unstable at high diversity. This means that even small changes to the model, such as non-linearities in how resources combine to generate species' growth, will result in persistent abundance fluctuations.
我们展示了在通过资源竞争相互作用并受到物种库迁移影响时，高度多样化的生态群落如何表现出持久的丰度波动。这些波动在特定的参数空间范围内稳健且可预测地出现。它们的起源与实现的物种多样性与资源数量的比值密切相关。这个比值是通过竞争来设定的，通过物种被推出和入侵的平衡来实现。当这个比值小于一，动力学将达到稳定的平衡点。当这个比值大于一，竞争排除原则决定了平衡点要么不稳定，要么处于边缘稳定状态。如果它们不稳定，系统就会从平衡点被排斥，丰度永远波动。虽然一些模型原则上允许并预测了处于边缘稳定的平衡点，但在高度多样性的情况下，它们变得结构不稳定。这意味着即使模型有微小的变化，例如资源如何组合产生物种生长的非线性，也会导致持久的丰度波动。
