Frog Diversity in Central Amazonian Macrophyte Beds: The Role of Local Environmental Gradients

Abstract

Ecological assemblages can be shaped by neutral, niche-based processes, or a combination of both. Understanding the influence of these processes and evaluating diversity measures based on taxonomic, functional, and phylogenetic metrics on the structure of ecological assemblages can show patterns and unravel community assembly mechanisms. Anurans represent a large part of the diversity of vertebrates in tropical environments and are a key group in assessing diversity patterns at different spatial scales. They can be terrestrial, aquatic and found in macrophyte meadows, which are aquatic and semiaquatic rooted or freely floating plants, that provide shelter, feeding, reproduction, spawning and nursery habitats for many organisms, including anurans, and can promote faunal long-distance dispersal and gene flow. Given that macrophyte meadows can influence the structure of anuran diversity, our study aimed to test the roles of spatial and environmental factors on the taxonomic, functional, and phylogenetic diversity of anuran assemblages found in floating meadows. Our study was held at Catalão Lake, Central Amazonia. Sampling on fifty 50 × 5 m plots occurred during the flood period, in macrophyte banks distributed throughout the lake. Geographical and environmental variables were measured at six equidistant points in each plot. We showed that macrophyte height influences taxonomic α diversity; macrophyte height and nearest margin distance influence taxonomic β diversity; water pH influences functional α diversity; and macrophyte height and nearest margin distance influence phylogenetic α diversity. Our study also suggests that geographic distances do not influence the anuran assemblage. We conclude that the anuran assemblages from this lake are niche-structured. Anurans, known for their limited dispersal capabilities, are influenced by the surrounding environmental conditions. Given that macrophytes are considered habitat patches for anurans, spatial processes have a limited impact in this environment.