GLOBAL-SCALE PATTERNS OF FISH SPECIES RICHNESS IN RIVERS

Explanations of spatial and temporal variation in species richness is a central theme in community ecology. Until recently, most research ha s focused on small-scale phe nomena, often emphasizing on local enviro nmental factors and, thus, poorly reflecting large-scale processes tha t organize species richness. In this paper, we analyze variations in s pecies richness of indigeneous freshwater fish on a worldwide scale. W e show that factors related to species-area and species-energy theorie s statistically explain most of the variation in freshwater fish speci es richness across continents. Historical events supposed to influence present distributions of fish are of little assistence in explaining variations in fish species richness at the global scale. Our model, wh ich uses easily measured factors, should also be of practical value to aquatic conservation biology and natural resource management.