Aim: Dispersal limitation, environmental selection and drift are known to influence both taxonomic similarity between communities and genetic similarity between populations. However, disentangling the relative roles of these processes on spatial patterns of differentiation - whether regarding taxonomic differentiation between communities or genetic differentiation between populations - is challenging. Investigating whether spatial patterns of taxonomic differentiation and genetic differentiation are correlated (β-SGDCs) is a promising approach to address this issue. Here, we investigated β-SGDCs over broad spatial scales and 22 freshwater fish species to elucidate the processes shaping taxonomic and genetic differentiations between drainage basins. Location: Global scope, data mainly from Europe and North America. Taxon: Actinopterygii and Petromyzontiformes (freshwater fishes). Methods: We used Mantel tests to investigate the raw correlation between taxonomic and genetic differentiations. We carried out multiple regressions to characterise the effects of geographic distance (proxy of dispersal limitation), environmental distance (proxy of environmental selection) and pairwise harmonic mean area between basins (proxy of drift) on taxonomic differentiation and genetic differentiation taken separately. We then analysed the correlation between the residuals of these two regressions with Mantel tests. Finally, we investigated whether the variation in β-SGDC between species was related to species traits. Results: We detected an overall positive β-SGDC, both for the raw and the residual correlations. This implies that, unmeasured effects, other than geographic distance, environmental distance and harmonic mean area, influence the β-SGDC observed. Values of β-SGDCs greatly varied between species, but this was not explained by any species traits. Main conclusions: Independently of the effects of geographic distance, environmental distance and harmonic mean area, the β-SGDC we observed suggests that historical processes strongly shaped the patterns of taxonomic and genetic differentiations between basins. Consequently, taxonomic differentiation may be an appropriate proxy to explain the influence of historical processes on genetic differentiation.