BIOGEOGRAPHIC PATTERNS OF COLOMBIAN FROGS AND TOADS

Using the data provided in Ruiz-Carranza et al. (1996) the distributions of the 540 species of frogs and toads are partitioned among ten ecogeographic units of Colombia defined on the basis of precipitation and elevation. Sorne lowlands areas (Pacific lowlands, Amazonia) exhibit high diversity (85-94 species) but lowlands areas in general are impoverished (30-52 species), especially when contrasted with upland areas. The three Andean cordilleras harbor between 87 and 121 species of frogs and toads, demonstrating that the biodiversity of Colombia resides primarily in its montane components, not in its lowland rainforests. When biological endemicity is separated from political endemicity, five areas of high endemicity remain (the three Andean cordilleras, the Sierra Nevada de Santa Marta, and the Pacific lowlands). We endeavor to explain this description by recourse to cladistic analyses of several groups of leptodactylid frogs where we find that the general pattem of diversification is by meaos of horizontal diversification (allopatric speciation) with a minor contribution from vertical diversification.