Spatial and interspecific differences in recruitment decouple synchrony and stability in trophic metacommunities

Abstract

Although synchronized oscillations in abundance across spatially segregated populations are a quasi-universal phenomenon, understanding their consequences for the stability of natural systems remains a major challenge. Theory has shown that even low levels of dispersal can synchronize and destabilize populations at both local and global scales. However, little is known about how persistent spatial and interspecific differences in recruitment influence the relationship between dispersal, synchrony, and stability across scales. Using a trophic metacommunity model to represent a set of local keystone food web modules connected via a global propagule pool, we show that spatial and interspecific differences in recruitment give rise to a complex relationship between dispersal, synchrony, and stability. Increasing dispersal from low to intermediate levels dampens both the synchrony and the magnitude of population oscillations and thus stabilizes their dynamics, regardless of interspecific differences in recruitment. However, increasing dispersal from intermediate to high levels generates increasingly large and synchronized population oscillations that destabilize the dynamics of all species. Importantly, when dispersal is high, interspecific differences in spatial recruitment patterns reduce the dispersal-induced destabilization via a trophic decoupling effect that buffers local population growth. Overall, our results suggest that spatial and interspecific differences in recruitment rates can interact in complex ways to alter the relationships between dispersal, synchrony, and stability in trophically structured metacommunities.