Dieta da rã-das-pedras (Thoropa miliaris) (Anura: Cycloramphidae) na Serra do Mar e Serra da Mantiqueira, Sudeste do Brasil

Abstract

The paucity of studies on biotic interactions (Eltonian shortfall) is one of the main impediments to the advance of the knowledge on biodiversity. Investigating the trophic ecology of a species is an essential step to fill such gaps. Brazil, despite having the greatest richness of anuran species in the world, has wide gaps in the knowledge on biotic interactions even for common species. An example is the rock river frog, Thoropa miliaris (Spix, 1824), endemic to rocky environments in the Atlantic Forest from southeastern Brazil to southern Bahia. In this study, we investigate if individuals of T. miliaris select their prey or consume them according to their availability in the environment. Besides, we tested whether the availability of potential prey and the diet of T. miliaris differ between two mountain ranges (Serra do Mar and Serra da Mantiqueira). Our hypothesis is that the species has a generalist diet and prey availability and the diversity of consumed prey are bigger in Serra do Mar, as a possible reflection of its higher primary productivity compared to Serra da Mantiqueira. For the diet analysis, we collected T. miliaris specimens and prey available in the environment in 10 localities along the Serra do Mar and Serra da Mantiqueira between November 2021 and January 2022. We captured frogs by hand and available prey using pitfall traps and leaf litter sifting. We identified the prey present in frogs’ stomach collected in the environment to the order taxonomic rank. Due to the high abundance and frequency of ants in collected samples, we identified them to genus rank. The environment did not provide significant variation in the diet of T. miliaris, and ants (Formicidae) were selectively consumed in greater volume, frequency, and abundance in the two mountain ranges. Our study is the most extensive to analyze and evaluate prey availability and the diet of a Cycloramphidae and, contrary to expected, T. miliaris does not have a generalist/opportunistic diet described for most anurans and diet differs little among populations