Journal Article Research Support, Non-U.S. Gov't fragmentación fragmentation Conectividad Meta-Analysis Research Support, U.S. Gov't, Non-P.H.S. Review connectivity dispersal dispersión disturbance diversidad diversity edge effects efecto de borde especies invasoras graph theory grasslands inbreeding depression invasion invasive species mating system modelos de redes network models pastizales perturbación pollination population size redes ponderadas