Functional biogeography of fluvial fishes across the conterminous U.S.A.: Assessing the generalisability of trait–environment relationships over large regions

Compared to taxonomic approaches, traits-based approaches are often implemented gain a more mechanistic understanding of how biotic communities respond changing environmental conditions, including landscape stressors. Studies evaluating trait–environment relationships have increased in prevalence over the last 2 decades, but such analyses rarely been conducted across continental extents which component regions exhibit substantial spatial variation stressors and natural conditions. Consequently, role biogeographic context remains under studied. Here, we evaluated generalisability conterminous U.S.A. advance our functional biogeography fluvial fishes. We sought to: (1) identify that were consistent regardless regional differences conditions; (2) address whether multivariate structure was comparable regions. used RLQ fourth-corner significant nine large ecoregions comprising These statistical provided framework analyse co-variation among 16 traits (e.g., trophic ecology, habitat preference) 17 variables representing 597 stream fish species whose abundances had recorded 45,183 reaches between 1990 2019. Trait–environment varied few consistent. Although some multiple ecoregions, strength varied. findings suggest most responsive conditions determined by distinct processes. Our add growing consensus dependent. Understanding complex geographic can inform ecological theory improve conservation efforts at broad extents.