CONICET | Buscador de Institutos y Recursos Humanos

Anthropogenic activities, such as grazing by domestic animals, are considered drivers ofenvironmental changes that may influence the structure of interaction networks. Thestudy of individual-based networks allows testing how species-level interaction patternsemerge from the pooled interaction modes of individuals within populations. Exponentialrandom graph models (ERGMs) examine the global structure of networks byallowing the inclusion of specific node (i.e. interacting partners) properties as explanatorycovariates. Here we assessed the structure of individual plant?frugivore interactionnetworks and the ecological variables that influence the mode of interactions underdifferent land-use (grazed versus ungrazed protected areas). We quantified the numberof visits, the number of fruits removed per visit and the interaction strength of mammalfrugivore species at each individual tree. Additionally we quantified ecological variablesat the individual, microhabitat, neighborhood and habitat scales that generatedinteraction network structure under the different land uses. Individual plant?frugivorenetworks were significantly modular in both land uses but the number of modules washigher in the grazed areas. We found interaction networks for grazed and ungrazed landswere structured by phenotypic traits of individual trees, by the microhabitat beneaththe tree canopy and were affected by habitat modifications of anthropogenic origin. Theneighborhood surrounding each individual plant influenced plant?frugivore interactionsonly at the grazed-land trees. We conclude that anthropogenic land uses influencethe topological patterns of plant?frugivore networks and the frugivore visitation to treesthrough modification of both habitat complexity and the ecological traits underlyinginteractions between individual plants and frugivore species.