Modularity and robustness of a plant-frugivore interaction network in a disturbed tropical forest

Tropical forests are undergoing a biodiversity crisis including defaunation processes. Structure and function of biotic communities in disturbed ecosystems can be assessed with network analyses of interspecific interactions. In a disturbed tropical forest we studied the network of interactions between fruiting plants and three groups of frugivorous animals, determining the structure, modular roles of species and the robustness of the network under simulated extinction scenarios based on species strength (SS) (relevance), species role (SR) (connectivity) and body size (vulnerability). We recorded 5,347 interactions between 63 frugivore and 60 plant species. The network had a modular structure with four modules: (1) plants with exposed fruits consumed by bats; (2) plants with juicy fruits consumed by larger birds; (3) plants with dry high-lipid-content fruits consumed by migratory birds; and (4) generalist plants consumed by several frugivores (three guilds). Robustness of the network was lower when species with high SS or important connectivity roles (i.e., module hubs) were lost first; when larger animals were lost first the network was more robust than in the other scenarios. Our results suggest that modularity may protect disturbed communities against species loss. We provide bases for developing ecologically-sound measures for the conservation of ecological interactions in anthropogenic landscapes.