Regional vs local drivers of phylogenetic and species diversity in stream fish communities

Summary Regional and local processes are thought to influence community phylogenetic and species diversity, but have proved challenging to distinguish. We disentangled the effects of local (limiting similarity and habitat filtering) and regional processes (biogeography, history and geographical constraints) on the species and phylogenetic diversity of native riverine fish communities across France. Fish species richness (SR), phylogenetic diversity (estimated as the phylogenetic species variability metric, PSV) and trait evenness (estimated from 17 ecological and life‐history traits) were estimated for fish at 932 sampling sites across 42 river basins in France. A phylogenetic signal in traits and species responses to environment variation were estimated using linear models. Null models were developed to test whether river basins constrain the PSV of the communities. Hierarchical linear models were fitted to PSV and SR to partition the variance explained by local and regional processes. Fish species richness and phylogenetic diversity were negatively correlated across sites (r = −0.589, P