Abiotic and Biotic Factors as Predictors of Species Richness on Madagascar

Madagascar contains a diversity of endemic species. Yet levels of species richness vary among the isolated habitats scattered across the island. A number of ecological factors have been advanced to account for patterns of species richness. In particular, abiotic factors such as habitat area, latitude, altitude, temperature, and rainfall have been suggested to account for ultimate differences in the number of species a habitat may support. Biotic variables such as vegetation type have been suggested as more proximate factors in determining the diversity of habitats available for animals to occupy. Several studies have included Malagasy locales in evaluating large-scale relationships between ecological variables and species richness (e.g., [], []; []; []; []). This study combines data on geography, topography, climate, and vegetation with species lists from 27 national parks, reserves, and other protected areas to specifically address biogeographic patterns of species richness on Madagascar. Ecological variables are considered individually in order to determine which biotic and abiotic factors may best predict primate, mammal, bird, reptile, and amphibian richness.