Division of Theoretical Biology, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183, Linköping, Sweden.
Department of Ecology and Evolution, University of Chicago, 1101 East 57th Chicago, Chicago, IL, 60637, USA.
Nat Ecol Evol. 2017 Dec;1(12):1870-1875. doi: 10.1038/s41559-017-0357-6. Epub 2017 Oct 23.
The stability of complex ecological networks depends both on the interactions between species and the direct effects of the species on themselves. These self-effects are known as 'self-regulation' when an increase in a species' abundance decreases its per-capita growth rate. Sources of self-regulation include intraspecific interference, cannibalism, time-scale separation between consumers and their resources, spatial heterogeneity and nonlinear functional responses coupling predators with their prey. The influence of self-regulation on network stability is understudied and in addition, the empirical estimation of self-effects poses a formidable challenge. Here, we show that empirical food web structures cannot be stabilized unless the majority of species exhibit substantially strong self-regulation. We also derive an analytical formula predicting the effect of self-regulation on network stability with high accuracy and show that even for random networks, as well as networks with a cascade structure, stability requires negative self-effects for a large proportion of species. These results suggest that the aforementioned potential mechanisms of self-regulation are probably more important in contributing to the stability of observed ecological networks than was previously thought.
复杂生态网络的稳定性既取决于物种之间的相互作用，也取决于物种对自身的直接影响。当一个物种的丰度增加会降低其个体增长率时，这种直接影响被称为“自我调节”。自我调节的来源包括种内干扰、同类相食、消费者与其资源之间的时间尺度分离、空间异质性和将捕食者与其猎物联系起来的非线性功能反应。自我调节对网络稳定性的影响还没有得到充分研究，此外，自我效应的经验估计也带来了巨大的挑战。在这里，我们表明，除非大多数物种表现出很强的自我调节，否则经验性食物网结构就无法稳定。我们还推导出了一个能够高度准确预测自我调节对网络稳定性影响的分析公式，并表明即使对于随机网络和具有级联结构的网络，稳定性也需要大多数物种具有负的自我效应。这些结果表明，与之前的想法相比，上述潜在的自我调节机制可能在促进观测到的生态网络稳定性方面更为重要。
