High species turnover shapes anuran community composition in ponds along an urban-rural gradient

The rapid expansion of urban areas in which natural and semi-natural areas are replaced by human infrastructure, is a major threat to biodiversity worldwide. However, little is known about how the structure of biotic communities is affected by urbanization in the tropics. Here, we tested the effect of land use types and pond size in urban and rural areas on frog species richness and community composition in central Brazil. We selected 20 ponds differing in size and surrounding levels of urbanization and native vegetation cover. We quantified relationships between environmental variables and species richness and community composition using a Poisson GLM and a distance-based Redundancy Analysis (db-RDA), respectively. Variation in species richness was positively related to pond size and negatively related to the amount of urbanization in a 500 m buffer around ponds. Community composition was mainly driven by species turnover than by nestedness, with turnover being explained primarily by urbanization and native vegetation cover. Our results indicate that urbanization negatively influences species richness. Moreover, as the amount of urbanization increased, several species were replaced by other taxa better adapted to urban environments. Our results indicate that understanding the effects of urbanization on amphibians in tropical cities might improve conservation strategies, such as preserving large ponds in urban environments.