No abstract

Climate change is asymmetrically altering environmental conditions in space, from local to global scales, creating novel heterogeneity. Here, we argue that this novel heterogeneity will drive mobile generalist consumer species to rapidly respond through their behavior in ways that broadly and predictably reorganize—or rewire—food webs. We use existing theory and data from diverse ecosystems to show that the rapid behavioral responses of generalists to climate change rewire food webs in two distinct and critical ways. Firstly, mobile generalist species are redistributing into systems where they were previously absent and foraging on new prey, resulting in topological rewiring—a change in the patterning of food webs due to the addition or loss of connections. Secondly, mobile generalist species, which navigate between habitats and ecosystems to forage, will shift their relative use of differentially altered habitats and ecosystems, causing interaction strength rewiring—changes that reroute energy and carbon flows through existing food web connections and alter the food web’s interaction strengths. We then show that many species with shared traits can exhibit unified aggregate behavioral responses to climate change, which may allow us to understand the rewiring of whole food webs. We end by arguing that generalists’ responses present a powerful and underutilized approach to understand and predict the consequences of climate change and may serve as much-needed early warning signals for monitoring the looming impacts of global climate change on entire ecosystems.

Community interactions (e.g., predation, competition) can be characterized by two factors: their strengths and how they are structured between and within species. Both factors play a role in determining community dynamics. In addition to trophic interactions, dispersal acts as an interaction between separate populations. As with other interactions, the structure of dispersal can affect the stability of a system. However, the primary structure that has been studied in consumer-resource models has been hierarchical dispersal, where between-patch dispersal rates increase with trophic level. Here we use analytical, numerical, and simulation approaches on a two-patch, three-species metacommunity model to investigate the relationship between structure and community stability and resilience. We show that metacommunity stability is greater in systems with both weak and strong dispersal rates. Our system is stabilized by the formation of patterns when predators disperse frequently and herbivores disperse rarely, and via asynchrony when both predators and herbivores disperse infrequently. Our results show how interaction strengths within both trophic and spatial networks shape metacommunity stability.