Instability of a hybrid module of antagonistic and mutualistic interactions

Abstract

AbstractMutualistic and antagonistic interactions coexist in nature. However, little is understood about their relative roles and interactive effects on multispecies coexistence. Here, using a three‐species population dynamics model of a resource species, its exploiter, and a mutualist species, we show that a mixture of different interaction types may lead to dynamics that differ completely from those of the isolated interacting pairs. More specifically, a combination of globally stable antagonistic and mutualistic subsystems can lead to unstable population oscillations, suggesting the potential difficulty in the coexistence of antagonism and mutualism. Mutualism‐induced instability arises from the indirect positive effect of mutualism on the exploiter. Furthermore, for a three‐species system with a stronger mutualistic interaction to persist stably, a weaker antagonistic interaction is required. Network studies of communities composed of one type of interaction may not capture the dynamics of natural communities.