Environmental versus biotic filtering: what if species traits contribute to both?

This study introduces a novel approach to assess the contribution of species traits to environmental and biotic filtering, and ultimately to community assembly. This approach assumes that a species trait can be associated with both the α component of the niche (reflecting resource use within communities) and its β component (reflecting position along environmental gradients). To highlight the significance of this concept, we analyzed traits related to large‐scale habitat preference, trophic resource use, microhabitat partitioning, and predation from 26 lacustrine fish communities in the Yangtze River basin, China. Null models were applied to assess trait dispersion patterns within and across communities. When traits were simply classified as being related solely to either abiotic (environmental) or biotic (interspecific interactions) filtering, our analysis only detected under‐dispersion among species with similar traits, indicating strong environmental filtering. However, when traits were assumed to have dual roles, an additional pattern emerged: species that were similar in traits related to resource use or habitat partitioning but dissimilar in environmental requirements were more likely to exhibit over‐dispersion, consistent with the influence of interspecific interactions. Our findings highlight the dual role of species traits in community assembly, shaping both environmental and biotic filtering processes. Recognizing this duality provides a more nuanced perspective on species coexistence mechanisms and the interplay between environmental constraints and interspecific interactions.