Connectivity among communities influences processes such as population persistence, genetic structure, and species diversity. While most research has focused on the magnitude of connectivity among communities, a growing body of work has demonstrated the importance of the spatial pattern of connectivity. In particular, the spatial geometry of connectivity influences asynchrony in constituent populations across sites that, in turn, promotes regional persistence and stability. However, spatial networks are overlain with a template of spatial environmental variation whose effects on synchrony and stability are not well characterized. Using spatially-explicit models, I explore how consumer-resource dynamics in trophic metacommunities are jointly influenced by connectivity patterns and spatial environmental variation. A number of case studies are considered, including regular, random, and branching river networks. Also considered are cases where spatial variation is random as well as those where model parameters vary with respect to network position.
Results/Conclusions
The modeled consumer-resource dynamics are capable of large amplitude fluctuations. In the presence of limited dispersal, population fluctuations synchronize across clusters of linked local habitats; the size of these clusters and degree of asynchrony among them strongly influences regional stability. Random spatial variation tends to interrupt clustering among local habitats, while spatial variation linked to network position typically enhances it. However, the effects on regional stability can be somewhat idiosyncratic in both cases: random spatial networks show somewhat limited enhancement of spatial clustering, whereas branching river networks show greater clustering when spatial variation is determined by the river’s branching level. Additionally, spatial shifts in parameter values can lead to local stability at certain sites without necessarily greatly contributing to stability regionally. These results show that spatial patterns of connectivity and the spatial distribution of environmental variation can have important consequences for the persistence and dynamics of metacommunities.