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Invasive Plants Versus Their New and Old Neighbors: A Mechanism for Exotic Invasion
Ragan M. Callaway,*Erik
T. Aschehoug
Invading exotic plants are thought to succeed primarily
because they have escaped their natural enemies, not because of novelinteractions with their new neighbors. However, we find that
Centaureadiffusa, a noxious weed in North America, has much
stronger negativeeffects on grass species from North America than on
closely relatedgrass species from communities to which
Centaurea is native. Centaurea'sadvantage
against North American species appears to be due todifferences in the
effects of its root exudates and how theseroot exudates affect
competition for resources. Our results mayhelp to explain why some
exotic species so successfully invadenatural plant communities.
Division of Biological Sciences, The University of Montana,
Missoula, MT 59812, USA.
*
To whom correspondence should be addressed. E-mail:
callaway{at}selway.umt.edu
Present address: The Nature Conservancy, 201 Mission
Street, San Francisco, CA 94105, USA.
The editors suggest the following Related Resources on Science sites:
In Science Magazine
NEWS OF THE WEEK
Mari N. Jensen (20 October 2000) Science290 (5491), 421a.
[DOI: 10.1126/science.290.5491.421a] |Summary »|Full Text »
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Enhanced fitness due to higher fecundity, increased defence against a specialist and tolerance towards a generalist herbivore in an invasive annual plant.