Does regional species diversity resist biotic invasions?
The role of regional species diversity in large-scale species ii,vasions h::s bee,, lai-gely controversial. On
the c,ne hand, it has been proposed thrlt diversity may facilitate invasion ' "diversity begets diversity")
because regions with hi~her di •.'ersity may indicate favorable conditions for many more species. On the
other hand, high diversity may indicate high levels of niche occupation, thus making it more difficult for
new species to invade. In the )ast, invasion biologists have evaluated how regional native and exotic
richness are related. Here, we test whether the range si,e of exotic species may be constrained by
regional native richness using plant data from three continental regions in the Northern Hemisphere, i.e.,
Europe, Eastern Asia, and North America. We found that regional native plant diversity is inversely
related to the range size of exotic species. :his result may be due to stronger species interactions such as
competition in species-rich habitats that limit the establishment and spread of exotic species.