Aggregated dispersal reduces spatial synchrony but promotes instability and extinction risk

Theory has shown that limited amounts of constant dispersal modeled via fixed probability distributions can promote both coexistence and stability in spatially coupled ecosystems. However, dispersal in nature varies spatiotemporally and only approximates such fixed distributions when averaged over many generations. As a result, assuming constant dispersal introduces an implicit separation of time scales between slow local species interactions and fast regional dispersal. Here, we relax this implicit assumption by using a strategic metacommunity model with spatially aggregated, temporally stochastic dispersal that varies at the same temporal scale as local trophic dynamics in order to reexamine the relationship between synchrony, stability, and persistence. We show that increasing the rate of stochastic dispersal alters the spatiotemporal dynamics of all species, especially relative to what theory has previously demonstrated under constant dispersal. Specifically, regardless of the degree of spatial aggregation, increasing the rate of stochastic dispersal increases the magnitude and the frequency of population fluctuations, while rapidly reducing their spatial synchrony and temporal autocorrelation. Furthermore, increasing spatial aggregation reduces both temporal stability and persistence by inducing boom‐and‐bust cycles that lead to frequent local extinctions, particularly when species disperse in an identical manner. Decreasing the degree of spatial aggregation or allowing species to disperse independently reduces the emergence of such boom‐and‐bust cycles and thus promotes both stability and persistence. Overall, our results demonstrate that relaxing the implicitassumption of separate time scales for local and regional processes can be critical for resolving the relationship between variable dispersal, synchrony and stability in metacommunities.