Anthropogenic activities, such as grazing by domestic animals, are considered drivers of environmental changes that may influence the structure of interaction networks. The study of individual‐based networks allows testing how species‐level interaction patterns emerge from the pooled interaction modes of individuals within populations. Exponential random graph models (ERGMs) examine the global structure of networks by allowing the inclusion of specific node (i.e. interacting partners) properties as explanatory covariates. Here we assessed the structure of individual plant–frugivore interaction networks and the ecological variables that influence the mode of interactions under different land‐use (grazed versus ungrazed protected areas). We quantified the number of visits, the number of fruits removed per visit and the interaction strength of mammal frugivore species at each individual tree. Additionally we quantified ecological variables at the individual, microhabitat, neighborhood and habitat scales that generated interaction network structure under the different land uses. Individual plant–frugivore networks were significantly modular in both land uses but the number of modules was higher in the grazed areas. We found interaction networks for grazed and ungrazed lands were structured by phenotypic traits of individual trees, by the microhabitat beneath the tree canopy and were affected by habitat modifications of anthropogenic origin. The neighborhood surrounding each individual plant influenced plant–frugivore interactions only at the grazed‐land trees. We conclude that anthropogenic land uses influence the topological patterns of plant–frugivore networks and the frugivore visitation to trees through modification of both habitat complexity and the ecological traits underlying interactions between individual plants and frugivore species.

1. Many invasion hypotheses postulate that introducing species to novel environments allows some organisms to escape population controls within the native range to attain higher abundance in the introduced range. However, introductions may also allow inherently successful species access to new regions where they may flourish without increasing in abundance.2. To examine these hypotheses, we randomly surveyed semi-arid grasslands in the native and two introduced ranges (12,000-21,000 km 2 per range) to quantify local abundance (mean cover per occupied plot) and occurrence (percentage of 1-m 2 plots occupied) for 20 plant introductions that included pest and non-pest species.For each of these metrics, we evaluated relationships between abundance in the introduced vs. native range (1) across all species and (2) according to designated pest status in the introduced range. We predicted that if escape from population controls primarily explained invader success, then these species would be more abundant in the introduced range; while if invader success was driven primarily by intrinsic species attributes, then their abundance would be correlated between ranges.3. Across all 20 invaders, we found that neither cover nor occurrence metrics were correlated between ranges. While cover was significantly higher in the introduced range, this result was driven by pest species. When the four pest species were excluded, cover but not occurrence was correlated between ranges. Interestingly, whereas cover of pest and non-pest species was comparably low in the native range, pest species cover increased sevenfold in the introduced range. Synthesis.Our results confirm previous findings that local abundance in the native range predicts local abundance in the introduced range for many introduced plants, suggesting that intrinsic species' attributes may determine most invasion outcomes.However, we also found that some species increased in local abundance in the 728 |

We found support for our hypothesis, raising in turn the possibility that competition and colonization are positively associated in seed morphs of heterocarpic species with enhanced exozoochory of larger seeds. These findings are not consistent with those from heterocarpic species with enhanced anemochory of smaller seeds or slower-germinating seeds. Our results additionally suggest that pappus and non-pappus seeds of C. solstitialis display a task-division strategy in which pappus morphs colonize and preempt unoccupied sites through improved dispersal and fast and large emergence of seedlings with increased competitive abilities, whereas non-pappus morphs promote site persistence through delayed germination and dormancy. This strategy may contribute to the success of C. solstitialis in highly variable environments.