Spatial Patterns and Determinants of Multidimensional Beta Diversity in the United States Freshwater Fishes
Congjun Xu, Huiru Xue, Jiping Li, Yingxin Li, Chenggong Du, Naisen Liu, Jun Xu, Wei Zhang, Taotao Dai, Guohuan SuABSTRACT
Aim
Understanding the spatial patterns and drivers of biodiversity is foundational to ecology and biogeography and crucial for effective conservation. Given the critical ecological role of freshwater fishes, large‐scale studies examining the multiple dimensions of their beta diversity are urgently needed.
Location
The United States.
Methods
We analysed the beta diversity of 786 freshwater fish species across 1873 watersheds in the US by integrating their distribution, functional traits and phylogeny. Taxonomic, functional and phylogenetic beta diversity were deconstructed into nestedness and turnover components. Boosted Regression Tree (BRT) models then quantified the partial dependency of contemporary, historical climate and geographical environmental factors on each dimension.
Results
Our findings revealed that the geographical distribution patterns of the three dimensions of beta diversity, including their nestedness and turnover components, exhibited substantial congruence across the US freshwater fish communities. Taxonomic beta diversity (average 0.43 ± 0.13) was primarily driven by turnover (0.25 ± 0.13), whereas nestedness contributed more strongly to functional beta diversity (0.34 ± 0.16; total beta diversity = 0.52 ± 0.19) and phylogenetic beta diversity (0.17 ± 0.09; total beta diversity = 0.30 ± 0.11). Contemporary precipitation and climate anomalies played significant roles in shaping beta diversity. Late Quaternary glacial–interglacial climate‐change velocity, elevation, runoff and geographical distance emerged as the primary explanatory variables for the beta diversity patterns.
Main Conclusions
This study examines the dominant patterns and drivers of multidimensional beta diversity in US freshwater fishes. Functional beta diversity exceeded taxonomic and phylogenetic dimensions. Taxonomic diversity was driven mainly by species turnover, while functional and phylogenetic diversity were dominated by nestedness, with all three showing significant spatial correlations. These patterns were primarily shaped by Late Quaternary climate‐change velocity, elevation, runoff and geographic distance. We recommend prioritising conservation in central and western US watersheds with strategies tailored to turnover‐ and nestedness‐dominated regions.