Department of Mathematics, University of Fribourg, Fribourg, Switzerland.
University of Applied Sciences Western Switzerland - HES-SO, Yverdon-les-Bains, Switzerland.
PLoS Comput Biol. 2018 Feb 8;14(2):e1005988. doi: 10.1371/journal.pcbi.1005988. eCollection 2018 Feb.
The consensus that complexity begets stability in ecosystems was challenged in the seventies, a result recently extended to ecologically-inspired networks. The approaches assume the existence of a feasible equilibrium, i.e. with positive abundances. However, this key assumption has not been tested. We provide analytical results complemented by simulations which show that equilibrium feasibility vanishes in species rich systems. This result leaves us in the uncomfortable situation in which the existence of a feasible equilibrium assumed in local stability criteria is far from granted. We extend our analyses by changing interaction structure and intensity, and find that feasibility and stability is warranted irrespective of species richness with weak interactions. Interestingly, we find that the dynamical behaviour of ecologically inspired architectures is very different and richer than that of unstructured systems. Our results suggest that a general understanding of ecosystem dynamics requires focusing on the interplay between interaction strength and network architecture.
生态系统中复杂性产生稳定性的共识在 70 年代受到了挑战，最近这一结果被扩展到了受生态学启发的网络中。这些方法假设存在可行的平衡，即正丰度。然而，这一关键假设尚未得到验证。我们提供的分析结果辅以模拟结果表明，在物种丰富的系统中，平衡可行性消失了。这一结果使我们陷入了一种不舒服的境地，即在局部稳定性标准中假设存在可行的平衡远未得到保证。我们通过改变相互作用结构和强度来扩展我们的分析，发现无论相互作用强度如何，只要物种丰富度较低，可行性和稳定性就可以得到保证。有趣的是，我们发现受生态学启发的架构的动态行为与非结构化系统非常不同，也更加丰富。我们的结果表明，要全面了解生态系统动态，就需要关注相互作用强度和网络结构之间的相互作用。
