Interaction between ants and plants bearing extrafloral nectaries : Community patterns along a latitudinal gradient in the cerrado biome

Abstract

Ants (Hymenoptera: Formicidae) are among the most prominent groups of terrestrial organisms in terms of diversity, abundance, and relative biomass, especially on vegetation. Ant-plant interactions can determine the evolution of specific adaptations, and mediate the differentiation of plant lineages. Extrafloral nectaries (EFNs) are glandular structures that commonly mediate ant-plant interactions by providing liquid food resources for ants. Ants in turn may benefit plants by reducing the negative effects of herbivores on plant tissues. EFNs are particularly abundant amongst cerrado plants, and strongly promote ant foraging activity on foliage. This interaction, however, may vary in space and can be conditioned by a range of environmental factors and/or by the distribution of organisms. Thus, from a plant's viewpoint, the outcome of EFN-mediated ant-plant interactions (including ant-derived herbivory reduction) may also be conditioned. In this research project, we will investigate how the interaction between ants and EFN-bearing plants is affected by variation in climatic parameters, soil quality, and phylogenetic relationships between local plant species along a latitudinal gradient in the cerrado biome comprising nearly 2,100 km. First, we will investigate how the abundance of EFN-bearing plants varies along the gradient. Then we will study how the protective services by visiting ants to plants with EFNs (through reduction of herbivory) vary along the same gradient. Finally, we will investigate whether ant-plant interactions mediated by EFNs affect the phylogenetic structure of local plant communities relative to other environmental factors (e.g. climate, or soil).