Warming-induced switches in dominance are built into intraguild predation systems

Abstract

Warming affects food webs globally. In the iconic intraguild predation food web module consisting of a basal resource, a specialist consumer, and an omnivorous predator, resource enrichment can favor the predator by increasing the relative importance of intraguild predation compared to resource competition. Here, we integrate empirically established thermal scaling relationships into a model of intraguild predation. We show that warming can shift the power balance between consumer and predator and affect invasion and equilibrium outcomes by inducing changes to resource enrichment - without any differences in thermal optima between species. The nature of these shifts depends on the thermal scaling of resource self-regulation and the strength of resource top-down regulation. We also test the capacity of several generic early warning signals to predict these shifts and find variance-based indicators to be more reliable than autocorrelation-based ones. Our results have implications for predictive food web ecology and biocontrol applications under global change.