Temporally robust occupancy frequency distributions in riverine metacommunities explained by local biodiversity regulation

Abstract

Aim: The mechanisms determining the distribution of the number of sites species occupy, the occupancy frequency distribution (OFD), remain incompletely understood despite decades of research. To explore the dominant mechanisms responsible for the shape and temporal dynamics of empirical OFD, we develop a simple patch occupancy framework with intrinsically regulated local richness and fit the model to a highly replicated dataset describing macroinvertebrate, macrophyte and diatom occupancy. Location: England. Time period: Up to (Formula presented.) years between 1990 and 2020. Major taxa studied: Macroinvertebrates, macrophytes and diatoms. Methods: We study the OFD in a highly replicated dataset of freshwater metacommunities in England across time. We consider temporal change in species richness, composition, and in the shape of the OFD. Goodness-of-fit of the steady state of a simple patch occupancy model—which predicts a log-series OFD—to the empirical observations is assessed. Additionally, we test the capacity of the model to predict metacommunity-scale processes. Results: Our model provides a consistently good fit to empirical OFDs. It can additionally be used to predict metacommunity-scale species turnover. Main conclusions: Our results support the view that metacommunity structure reflects a dynamic steady state controlled by local limits to coexistence.