Plants that have naturalized as aliens abroad have also become more common at home during the Anthropocene

Abstract Changes in species' native range size and occupancy have been dramatically accelerated by anthropogenic pressures in the last centuries. At the same time humans have introduced thousands of species beyond their historic range limits, and some of these have established self-sustaining populations (i.e. become naturalized). It is known that particularly common plant species have become naturalized, but how dynamics in native distributions relate to global naturalization is unknown. We retrieved data on grid-cell occupancy of native vascular plant species for 10 European regions, for at least two periods, to calculate for each species an occupancy-change index. For nine of the ten regions, we found a significant increase in global naturalization with both the early period occupancy and occupancy-change index. This finding shows that many of the plant species expanding globally as naturalized aliens are also expanding within their native ranges and suggests that the same drivers underlie both processes.