Synthesis: “Dormancy in metacommunities”
Nathan I. Wisnoski, Mathew A. Leibold, and Jay T. Lennon (Aug 2019)
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Dormancy modifies key predictions from metacommunity ecology offering new explanations for spatial patterns of biodiversity
Metacommunity ecology has primarily focused on how dispersal influences biodiversity across a landscape. However, many species possess the ability to engage in dormancy, a reversible state of reduced metabolism, which allows them to “disperse through time”. As a result, colonization of a local community can occur from an internal “seed bank” of dormant organisms, not just from other habitat patches, as is commonly assumed in metacommunity theory.
Using simulation models, the authors show that dormancy can modify patterns of biodiversity across spatial scales in the metacommunity. The influence of dormancy on these patterns may further depend on whether dispersal and dormancy are correlated (positively or negatively). In an analysis of aquatic invertebrates that live in tropical bromeliads, the authors find evidence for correlations between dispersal and dormancy strategies. Evidence from the literature suggests colonization from the seed bank is typically most important following local disturbances or in spatially isolated communities where dispersal is limiting. Our work also has implications for understanding and predicting species invasions. More broadly, dormancy in the context of metacommunity ecology may provide alternative explanations for commonly observed biodiversity patterns and could improve our understanding of eco-evolutionary dynamics and ecosystem functioning across spatial scales.
Although metacommunity ecology has improved our understanding of how dispersal affects community structure and dynamics across spatial scales, it has yet to adequately account for dormancy. Dormancy is a reversible state of reduced metabolic activity that enables temporal dispersal within the metacommunity. Dormancy is also a metacommunity-level process because it can covary with spatial dispersal and affect diversity across spatial scales. We develop a framework to integrate dispersal and dormancy, focusing on the covariation they exhibit, to predict how dormancy modifies the importance of species interactions, dispersal, and historical contingencies in metacommunities. We used empirical and modeling approaches to demonstrate the utility of this framework. We examined case studies of microcrustaceans in ephemeral ponds, where dormancy underlies metacommunity dynamics, and identified constraints on the dispersal and dormancy strategies of bromeliad-dwelling invertebrates. Using simulations, we showed that dormancy can alter classic metacommunity patterns of diversity in ways that depend on dispersal–dormancy covariation and spatiotemporal environmental variability. We propose that dormancy may also facilitate evolution-mediated priority effects if locally adapted seed banks prevent colonization by more dispersal-limited species. Last, we present testable predictions for the implications of dormancy in metacommunities, some of which may fundamentally alter our understanding of metacommunity ecology.