Anuran assemblage composition and distribution at a modified environment in Três Marias reservoir, south-eastern Brazil

Abstract

We assessed the influence of environmental features on anuran species distribution in Pirapitinga, an island formed by the filling of a reservoir in south-eastern Brazil. We investigated whether the species exhibited preferences towards certain habitat types and the existence of niche partitioning. We recorded 474 individuals from seven species. Although considered as generalists, these species were not distributed randomly, but according to specific habitat preferences that happened to be fulfilled by the shores of the reservoir. Niche overlaps were higher than expected by chance during the wet season, when most species were active, but not different from random during the dry season. Environmental variables seemed to be important and promote aggregation of several anuran species at the same habitats. Interspecific signals may be used for this purpose, and competition is probably small or less important than the benefits provided by choosing the most suitable habitats in this impacted environment.

Keywords:

• Anura
• reservoir
• anthropogenic impact
• habitat preference
• niche

Acknowledgements

We are thankful to Izabela M. Barata, Isabela Lazarotti and Júlia O. L. da Cruz for help during fieldwork, to M. Wachlevski, Luciana B. Nascimento, Henrique Paprocki, Hélio da Silva and two anonymous reviewers for helpful suggestions in previous versions of this manuscript, and to the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (Ibama) for logistics and permits. A Research Productivity grant (305889/2007-9) was provided to P. C. Eterovick by CNPq. We are especially grateful to the whole staff of Ibama who invited us to do this study and welcomed us and did everything to help in every field trip.