Bee community assembly is regulated by functional traits in pristine tropical forest environments

Understanding the drivers of bee beta diversity across pristine environments in the Amazon is critical for ensuring biodiversity conservation, restoration, sustainable land use planning and economic development. Here, we aim to reveal the patterns of among-site variation in bee communities between pristine open habitats and pristine forest formations in the Amazon using standardized bee surveys across sites and trait-based analyses (body size, sociality, nesting, buzz pollination and color). We quantified dissimilarity patterns and evaluated environmental filtering effects to test (1) whether functional diversity can better predict bee beta diversity than taxonomic diversity can; (2) whether open habitats are less diverse; (3) whether a subset of forest formations occurs; and (4) whether environmental filtering determines the predominant bee traits for each environment. Our results revealed high overall beta diversity across all pristine environments, which was driven primarily by species and functional trait turnover. Compared with taxonomic metrics, functional beta diversity better captured among-site variation, highlighting distinct ecological filtering between habitats to select different sets of traits. A portion of open habitat communities was functionally nested within forest assemblages, suggesting that forests may serve as species reservoirs for open habitats. Forests supported a richer taxonomic and functional bee assemblage, while open habitat communities exhibited specialized traits, including solitary behavior, exposed nesting, dark coloration, and buzz pollination. These findings highlight the importance of landscape heterogeneity and trait-based approaches, which should be incorporated into environmental management, restoration, and biodiversity offsetting plans. From a conservation perspective, our results stress the need to maintain open habitat patches (regardless of their size), which must remain embedded within a forest matrix. With respect to restoration, we show that the restoration of open habitats should consider the recovery of adjacent forest habitats to support ecological functionality. Integrated efforts are needed to recognize landscape heterogeneity as a fundamental component of ecological resilience in the Amazon. The incorporation of functional beta diversity into conservation and restoration planning increases the maintenance in the provision of ecosystem services and environmental resilience in Amazonian landscapes.