A ecologia em miniatura: o menor tetrápodo do Brasil, Brachycephalus didactylus (Izecksohn, 1971) (Anura: Brachycephalidae) em uma área de Mata Atlântica no Espírito Santo, Sudeste do Brasil

Abstract

The miniaturization process in anurans may have ecological implications as the clutch size reduction, increasing eggs relative sizes and direct development. The resulting reduced mouth size also tends to be a limiting factor in the prey consumption by these smaller frogs, making available only a restricted range of tiny prey. Thus, we studied some ecological parameters as the sexual dimorphism, some reproductive characters, the diet and its relationship with invertebrates availability and micro-habitat use, of a Brachycephalus didactylus anuran population in an Atlantic Rainforest area in southern state of Espírito Santo. This parameters were studied aiming to increase knowledge on these species. The data sampling occurred in 2011, in the dry and rainy seasons. Brachycephalus didactylus had sexual dimorphism, with females being larger than male ones. The larger size of females probably results from intra-sexual selection, to allow greater investment in egg mass, since the species has a considerably small clutch size (two to three eggs).The diet of B. didactylus was composed by a relatively broad spectrum of prey (17 items), with high proportions of small prey such as Acari and Collembola. The consumption of Formicidae (ants) was avoided by B. didactylus, despite this being the most abundant prey in the leaf litter. The small mouth size of the B. didactylus females limited them to the consumption of small prey, with larger individuals consuming a greater number of preys. Finally, B. didactylus presented an essentially horizontal habitat use, and is more often found in leaf litter on the forest floor.