Laura del Rio-Hortega, Irene Martín-Forés, Isabel Castro, José M. de Miguel, Belén Acosta-Gallo

Associated with the introduction of exotic species in a new area, interactions with other native species within the recipient community occur, reshaping the original community and resulting in a unique assemblage. Yet, the differences in community assemblage between native and invaded ranges remain unclear. Mediterranean grasslands provide an excellent scenario to study community assembly following transcontinental naturalisation of plant species. Here we compared the community resemblance of plant communities in Mediterranean grasslands from both the native (Spain) and invaded (Chile) ranges. We used a novel approach based on network analysis applied to co-occurrence analysis in plant communities, allowing us to study the coexistence of native and alien species in central Chile. This useful methodology is presented as a step forward in invasion ecology studies and conservation strategies. We found that community structure differed between the native and the invaded range, with naturalised species displaying more significant interactions and playing a key role within the invaded community. In addition, alien species displayed positive interactions among them within the communities in the invaded range. Alien species acting like keystones within the Chilean grassland communities might exacerbate the threat posed by biological invasions for the native biodiversity assets. We suggest controlling the spread of the alien species identified as keystones and developing early detection strategies in surrounding areas as management guidelines.