Patterns of endemism in riverine fish of the northern hemisphere

Loss of endemic species represents a symptom of general degrading ecosystem conditions that is the indirect result of biodiversity alteration. Here, we developed a predictive model relating species richness of endemic riverine fishes to measured biological, climatic, and historical variables using data from 118 rivers distributed all over the Northern Hemisphere. In a minimally adequate multiple general least square model, total riverine fish species richness, historical biogeography (Pleistocene glaciations), and contemporary climate accounted for 63% of the variability in endemic species richness : the strongest correlate being riverine fish species richenss. Our findings suggest that (1) endemism and richness patterns are generally similar (fish diversity "hot-spots" areas sustain higher endemic species richness) ; (ii) glaciation in the Pleistocene have had a significant negative influence on endemic species richness in the more septentrional areas ; and (iii) certain basins situated in desertic areas (subtropical dry-zone of deserts) have unusually high numbers of endemics. These last areas should not be overshadowed when setting conservation priorities. (Résumé d'auteur