MEPS 613:67-76 (2019)  -  DOI: https://doi.org/10.3354/meps12908

ABSTRACT: Dispersal is a key force driving patterns of biodiversity. However, temporal variation in dispersal due to seasonality, weather, and other stochastic forces is an understudied aspect of the dispersal-diversity relationship. Metacommunity theory predicts temporal variation in dispersal can alter species distributions across patches. We empirically tested the hypothesis that variation in dispersal can modify the nonlinear dispersal-diversity relationship. Using a mesocosm experiment, we factorially manipulated variation in and intensity of dispersal in invertebrate grazer communities associated with nearshore seagrass ecosystems. Higher dispersal intensity led to higher grazer abundance, higher species richness (alpha diversity), and—when dispersal was variable—lower compositional similarity among patches (higher beta diversity). Within each dispersal intensity treatment level, temporal variation in dispersal decreased alpha diversity and increased beta diversity, with strongest effects at low- and intermediate-intensity dispersal. Our results provide the first empirical evidence that temporal variation in dispersal can substantially modify the well-described dispersal-diversity relationship for both alpha and beta diversity. Broadly, our results provide increasing evidence for the effects of spatial and temporal variability in modifying the role of the ecological processes driving marine metacommunity structure.

KEY WORDS: Community assembly · Jensen’s inequality · Larval supply · Seagrass · Metacommunity