Review and analysis of altitudinal distribution of the Andean anurans in Colombia

Abstract

In the following work we examine the richness and altitudinal distribution of Colombian Andean anurans trying to emphasize patterns of distribution. We also supply an updated checklist of Andean anurans in Colombia. At present, Colombian harbors about 396 Andean frogs: 153 species in the Cordillera Occidental, 187 species in the Cordillera Central, and 131 species in the Cordillera Oriental. Of these, the Cordillera Oriental presents the higher number and percentage of endemic species. The frequency distribution of altitudinal ranges for Colombian Andean frogs shows that the majority of species have narrow altitudinal ranges, less than 500 m altitude, and only a few species have broad altitudinal distributions. On the other hand, lowland species have broader altitudinal ranges than do highland species. The hypothesis of a wider altitudinal range of highland anurans is therefore not supported. Finally, the averages of the Jaccard similarity indices for the Andean anurans along altitudinal gradients in Colombian are approximately similar to those of other tropical anurans reported by Huey (1978), but notably lower than those of anurans of temperate localities. Thus, these results are in concordance with Janzen's hypothesis (1967) about a broader altitudinal range for temperate species, likely because of their higher thermal tolerance.