Fish community trait dissimilarity dampens synchronizing effect of environmental fluctuations

Spatial synchrony, defined as the synchronized temporal fluctuations in species or community abundances across different locations, has implications for ecological persistence and stability and has received renewed attention in the context of rapid environmental changes. It is shaped by both biotic and abiotic drivers, with shared environmental fluctuations expected to promote synchrony in population dynamics, and dissimilarity in species composition expected to enhance asynchrony. Exploring spatial synchrony using trait-based approaches may provide new insights into the underlying drivers of community dynamics. Here, we investigated the drivers of spatial synchrony in the thermal affinity of fish communities (i.e., thermal community synchrony) within river basins in Europe, Australia, and the United States using multi-membership mixed models accounting for spatial, environmental and community dissimilarity. Our results show that synchrony in fish community thermal affinity decreases wi..., , # Fish community trait dissimilarity dampens synchronizing effect of environmental fluctuations Dataset DOI: [10.5061/dryad.np5hqc08z](https://doi.org/10.5061/dryad.np5hqc08z) ## Description of the data and file structure This dataset includes the variables to run the statistical analysis. Variables are as follows – Details of structure and analysis given in adjoined R script **Thermal Community Synchrony** A standardized metric that quantifies synchrony in temporal fluctuations of thermal CWMs between site pairs. Values range from 0 (asynchronous) to 1 (perfect synchrony), accounting for unequal community variances. **Thermal Niche Distance** Measures the relative difference in long-term average CWM between two sites, reflecting dissimilarity in dominant thermal traits. **Thermal Niche Overlap** Quantifies the similarity in the full distribution of thermal preferences between communities as the area of overlap between their thermal preference density curves (0 = no overlap, 1 = ..., ,