Renal structure in neotropical bats: Using stable isotopes to explore relationships between diet and morphology

The relationship between kidney structure and diet was examined in several species of bats from the tropics. The trophic level of the bats was determi ned by their stable nitrogen isotopic composition (delta N-15). The results indicate that the relative thickness of the renal medulla is directly rela ted to the trophic level of the bats. Additionally, we also determined the relationship between body mass and kidney structure. Relative medullary thi ckness was reciprocally related to body mass in animalivorous bats but no r elationship was found in phytophagous bats. Stable isotope analysis provide d a quantitative approximation of diet to test its relationship with kidney structure.