Fig 1.
Flowchart depicting the methodological workflow for this study.
(A) Geographic and phylogenetic data sources. (B) Compute speciation rates and geographic information (midpoint latitude and presence-absence matrix (PAM)). (C) Create final data sets by filtering freshwater species with geographic information and tip-level speciation rates (λ) values. (D) Assemblage-level analyses to evaluate the relationship between latitude and speciation rates. (E) Species-level analyses to evaluate the relationship between latitude and speciation rates. (F) Analysis of phylogenetic assemblage structure.
Fig 2.
Geographic pattern of species richness and speciation rates.
Patterns under different speciation rate metrics for the molecular dataset of 5,242 freshwater fish species. The upper row depicts the geographic patterns and the lower row their bivariate representations. Maps projection is in Mollweide equal area. The maps were created by the authors in R using the open-source “rnaturalearth” package [52] with public domain data from Natural Earth (http://www.naturalearthdata.com/). The figure is published under the CC BY 4.0 license.
Fig 3.
Relationship between species richness and speciation rates.
Bivariate plots for the molecular dataset of 5,242 freshwater fish species depicting the relationship between species richness and speciation rates for the three metrics: λDRw, λTCw, λClaDSw.
Fig 4.
Assemblage-level relationship between speciation rate and the absolute value of latitude.
Regressions considering different adjusted models (black – OLS model, red – OLS segmented). All X-axes are in degrees only for illustrative purposes. See Fig S2.1 to S2.2 in S2 Appendix for more detailed depictions of the statistical relationships.
Fig 5.
Species-level relationship between speciation rates and latitude.
Phylogenetic (top panel) and latitudinal (bottom panel) patterns of tip-level speciation rates. Patterns are shown for λDR, λTC, and λClaDS. Next to the phylogeny, we show the speciation rate per species at their corresponding midpoint along the latitudinal gradient (x-axis). Species have the same colors in both panels. The silhouettes of fishes were taken from phylopic (“https://www.phylopic.org/”).
Fig 6.
Geographic patterns of phylogenetic structure.
From top to bottom, phylogenetic diversity (PD), residual phylogenetic diversity (rPD), and (NRI) Net Relatedness Index of freshwater fish assemblages across the globe. Maps projection is in Mollweide equal area. The maps were created by the authors in R using the open-source “rnaturalearth” package [52] with public domain data from Natural Earth (http://www.naturalearthdata.com/). The figure is published under the CC BY 4.0 license.