Relações de tamanho, massa e dieta no nicho alimentar em uma comunidade de anuros na Mata Atlântica

Abstract

Anuran species from ecological communities are not randomly grouped. The determining factors in the structuring of anuran communities are, among others, the distribution of body sizes and trophic relationships among individuals of sympatric species. Anurans play an important role in the cycling of nutrients in the habitats where they live, acting as resources for predators and in controlling invertebrate populations. The rain forest litter is a microenvironment with great biological diversity, including vertebrate and invertebrate species. The Ecological Reserve of Guapiaçú is a Private Natural Reservein an area of Atlantic Forest and has different levels of conservation. Its greater portion is inserted in the Três Picos State Park, and the rest is in its zone of cushioning. The aim of this study were to describe the diet of the sympatric species of litter anurans, evaluating the potential existence of a resource partition promoted by morphological differences between individuals; describe patterns in food resource partition networks in order to identify if there is individual specialization in the diet of the individuals and also to verify the current knowledge about trophic resources partition in anurans in the world. Samples were carried out for 10 consecutive days in March 2015, using the time-limited active search method. The review on the resources partition by anurans in the world was carried out by a search of the databases between the years of 1945 and 2016. The current knowledge on the subject in the world is concentrated in the tropical regions, with Brazil having the largest number of studies. Some trends for anuran communities have been identified, but additional studies are needed so that further inferences can be made. The total abundance of invertebrates in the leaf-litter was 6,854 individuals, with a total of 43 orders. A total of 576 individuals of anurans, of 11 species, were analyzed. The individuals of the species sampled consumed a total of 2,706 preys of 40 categories. Formicidae was the most important prey for the community both numerically (32.9%) and frequency of occurrence (34.3%). Volumetrically, the most representative item was Orthoptera (27.0%). According to the importance index, the most representative prey for the community was Coleoptera (23.9%). There was greater dominance of Iscnocnema aff. guentheri, followed by other species of direct development (Hadaddus binotatus and Euparkerella brasiliensis). The species consumed prey little abundant in the environment and had a diet overlap 3.6 times greater than would be expected at random. There was no sexual or ontogenetic variation in the utilization of food resources by the three most abundant species of anurans in the community. There was no nesting or modularity in the diet of the three most abundant species. The data indicated that Iscnocnema aff. guentheri and Euparkerella brasiliensis had individual specialization in the diet, but it did not occur in Haddadus binotatus. The present study contributed to fill some of the existing knowledge gaps for the resources partition between litter anurans in the Atlantic Forest, and especially for the Três Picos State Park and the Guapiaçú Ecological Reserve.