Increasing interaction strength will destroy persistence of mutualistic ecological networks

In ecology, the relationship between stability of ecosystems and the interactions among species has always been a basic research focus. It is found by both experimental observation and model simulation that positive interaction (mutualism) is harmful to the stability of ecological networks. In this paper, we rigorously prove this fact for the mutualistic ecological networks. With the classical ecosystem model, we prove that the persistence (a measure of stability) of mutualistic ecological networks will be destroyed when the strength of interaction between any two species increases. This result explicitly clarifies the harmful role of mutualism on the persistence of mutualistic ecosystems and will provide guides to search strategies to eliminate the instability caused by positive interactions.