Diversity and resource selection of dung beetles in a relictual mountain forest in Brazil

Abstract

Most of the tropical ecosystems are now altered, consequently modifying the species diversity, composition and feeding behaviours. Precisely, the survival of species is dependent on their characteristics to endure the novel environments immersed in human-dominated landscapes. Thus, comparative studies of how different community attributes and trophic guilds respond to changes in land use would be useful. In this study, we analyzed diversity, composition and food selection of dung beetles in an Atlantic forest enclave (Ombrophilous forest remnant) from North-eastern Brazil. We sampled dung beetles using 60 pitfall traps distributed in our study region. Diversity and composition were estimated by using Hill numbers (or the effective number of species) and biomass of individuals and were compared among three types of vegetation structure (forest, forest edge and open pastures) and four different types of baits (human, pig, chicken and cattle excrements). We found that diversity measures weighted by biomass allowed better detection of the variation between habitat types and food preference than weighted by the number of individuals. The dung beetle biomass indicates that the spatial dominance of open pastures promote a drastic impoverishment of dung beetle diversity and composition. We also found that β diversity shows an evidence of homogenization on the resource food selection, related with the preference in the attraction of dung beetles to exotic omnivores. Our results show that replacing forests with cattle pastures modifies diversity, species composition, and resource food selection patterns, which could affect the ecosystem provision by dung beetles. Despite our study region is immersed in a human-dominated-landscape, forest remnants continue to hold a high diversity assemblage compared with most degraded environments.