Foraging preferences and interspecific competition generate multimodal complexity-stability relationships in an adaptive food-web framework

Ecological theory predicts that complex ecological networks are unstable and are unlikely to persist, despite many empirical studies of such complexity in nature. To resolve real complexity-stability relationships, coupling population dynamics and trait dynamics is considered to be an important way to understand the long-term stability of ecological community assemblages. However, modelling eco-evolutionary dynamics in ecologically realistic networks is still a challenge. Here, we establish an adaptive food web model to evaluate the complexity-stability debate in a mutualist-exploiters-specialist forager-generalist forager system. Our theoretical model predicts that the connectance-stability relationship may show positive monotonic (/), negative monotonic (\), peaked (∩) and double-peaked (oscillatory) patterns. Moreover, the double-peaked pattern is only obtained when both the adaptation intensity and interspecific competition are high, which may explain no complexity-stability relationships revealed in empirical data. Finally, we deduce that foraging adaptation alters positive and/or negative feedback loops to affect the stability of real food webs.

生态学理论预测，尽管学界已针对自然界中的此类复杂性开展了大量实证研究，但复杂的生态网络并不稳定，且难以持续存续。为厘清真实世界中的复杂性-稳定性关系，将种群动态与性状动态相结合被认为是理解生态群落组合长期稳定性的重要路径。然而，在具有生态学真实性的网络中构建生态-进化动态模型仍是一项挑战。在此，我们构建了自适应食物网模型（adaptive food web model），以在互利共生者-利用者-特化觅食者-泛化觅食者系统中评估复杂性-稳定性的学术争议。我们的理论模型预测，连接度-稳定性关系可能呈现四种模式：正单调型（/）、负单调型（）、单峰型（∩）以及双峰型（振荡型）。此外，仅当适应强度与种间竞争均处于较高水平时，才会出现双峰型模式，这或许可以解释为何实证研究中未发现明确的复杂性-稳定性关系。最后，我们推导得出，觅食适应性通过改变正、负反馈回路，进而影响真实食物网的稳定性。