Habitats determining local frog assemblages within aquatic macrophyte meadows in Amazonia, through species traits filtering

Investigating non‐random assemblages emerging in response to environmental gradients is relevant to understand mechanisms and processes affecting biodiversity. Species may be filtered from fractions of environmental gradients that limit dispersal, survival or ontogenetic development, which ultimately leads to biotic complementarities among sites. Non‐random assemblages as a response to environmental filtering have been widely demonstrated in Amazonian forests, but are rarely assessed in non‐forest ecosystems such as macrophyte meadows covering lakes. In this study, we sampled 50 plots (50 m long, 6 m wide) along continuous macrophyte meadows in a lake system in the lower Amazon River. Our main goal is to test the effects of distance from the lake bank, macrophyte height and composition (frequency of morphotype occurrence), air temperature and physicochemical properties of water (pH, dissolved oxygen, depth and temperature) on frog α and β‐diversity estimates, and frequency of species traits occurrence (abundance‐weighted body size, toe pads, foot webbing and tadpole habit). We found 16 species, for which local assemblages quantified by α and β‐diversity estimates were not random, but predicted by macrophyte height, morphotype composition and water depth. We have explicitly shown that species are filtered from fractions of these gradients through ecomorphological relationships, since morphological traits and tadpole habits were also selected by the vertical stratification provided by the vegetation cover and water depth. Overall, we present an investigation of assemblage ecology that is relevant to conservation, because the results suggest biotic complementarities within habitats that are rarely considered as distinct biogeographic units from the surrounding várzea forests. in Portuguese is available with online material. Resumo Investigar assembleias não aleatórias determinadas por meio de respostas das espécies a gradientes ambientais é relevante para compreendermos mecanismos e processos que afetam a biodiversidade. Espécies podem ser filtradas de porções de gradientes ambientais que limitam a dispersão, a sobrevivência ou o desenvolvimento ontogenético, o que em última instância gera complementaridade biótica entre locais. Assembleias não aleatórias em resposta a filtragem ambiental têm sido amplamente demonstradas em florestas Amazônicas, mas raramente em ecossistemas não florestais, como bancos de macrófitas aquáticas em lagos de várzea. Neste estudo,