Fig. 3.

Changes in taxonomic uniqueness and taxonomic similarity among fish faunas between historical and current situations for the six realms and at the world scale. The taxonomic uniqueness (percentage of river basin pairs sharing no species) (A), mean taxonomic similarity between pairs of river basins (measured using Jaccard’s similarity index) (B), and proportion of river basin pairs showing taxonomic homogenization (“h,” red), no changes (“0”, white) or taxonomic differentiation (“d,” blue) between historical and current situations (C) are shown. The historical situation indicates assemblages before introductions and extirpations attributable to human activities and corresponds to the preindustrial period. The current situation indicates today’s assemblages (native species − extirpated species + nonnative species).