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ABSTRACT Aim To disentangle the relative roles of environmental filtering (niche processes) and dispersal limitation (neutral processes) in structuring communities of a highly mobile tropical taxon, and to assess the implications for biodiversity patterns at broad spatial scales. Location Brazilian Amazon. Time Period 2011–2019. Major Taxa Studied Fruit‐feeding butterflies (Nymphalidae). Methods We surveyed 182 species across 148 plots spanning 730,000 km 2 and a broad climatic, edaphic and vegetational gradient. We used Generalized Linear Mixed‐effects Models (GLMMs), ordination methods and variance partitioning to quantify the unique and shared contributions of environmental and spatial predictors to species richness and composition. We also used distance–decay models to compare isolation‐by‐distance versus isolation‐by‐environment. Results Species richness increased with solar radiation, temperature and precipitation, and with distance from the equator. Environmental gradients, particularly climatic and soil variables, explained more variation in species turnover than geographic distance. For this highly dispersive group, the unique effect of dispersal limitation was weak, even across continental scales. Main Conclusions Our findings provide rare, large‐scale empirical evidence that niche‐based processes can dominate over neutral dynamics, even for organisms with high dispersal capacity and at broad spatial scales. By disentangling environmental and spatial effects, we show that climate, soil and vegetation are primary predictors of β‐diversity in a mobile tropical taxon, challenging assumptions that dispersal limitation necessarily strengthens with spatial extent. Because these predictors are sensitive to global change, our results offer a general framework for predicting macroecological biodiversity responses in mobile taxa and species‐rich ecosystems worldwide.
Rabelo et al. (Mon,) studied this question.