Amphibians and squamates in Amazonian flooded habitats, with a study on the variation of amphibian assemblages along the Solimões River

The dynamics and structure of tropical wetlands allow the occupation of unique biotic assemblages, and amphibians and squamates are no exception. In the megadiverse Amazonia, a seasonal flood pulse creates a mosaic of distinct habitats on the margins of large rivers. These highly dynamic habitats provide ecological opportunities for some species while negatively affecting the occurrence of others, thus leading to a partition of assemblages. Here, we review the knowledge on the diversity (i.e., species richness and composition) of amphibians and squamates occurring in these flooded habitats, and expand this knowledge with exploratory analyses on the spatial variation of amphibians along these habitats in the Solimões River, Brazil. We detected distinct patterns regarding the variation of species diversity, but none indicating that the amphibian assemblages are homogeneously distributed along this river. In fact, a drastic compositional turnover was detected in the transition of upper and middle courses of this river, alpha diversity gradually increased downstream, and beta diversity showed an irregular pattern. Our results are relevant for understanding levels of species association to these heterogeneous and threatened habitats, as well as to formulate new hypotheses on the historical and ecological processes shaping species distributions.