Natural selection for resistance to the allelopathic effects of invasive plants

Authors

  • RAGAN M. CALLAWAY,

    Corresponding author
    1. The Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA, and
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  • WENDY M. RIDENOUR,

    1. The Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA, and
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  • TREVOR LABOSKI,

    1. The Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA, and
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  • TIFFANY WEIR,

    1. The Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA, and
    2. Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, CO 80523, USA
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  • JORGE M. VIVANCO

    1. The Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA, and
    2. Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, CO 80523, USA
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Ragan M. Callaway (tel. 406 243 5077; fax 406 243 4184; e-mail ray.callaway@mso.umt.edu).

Summary

  • 1Exotic plant invasions often cause high mortality in native populations and therefore have the potential to be a powerful selective force.
  • 2We found that surviving individuals from North American communities that have experienced extensive invasion by Centaurea maculosa have higher tolerances to the Eurasian invader than individuals from communities that did not experience invasion.
  • 3Some native species grown from the seed of individuals that survived Centaurea invasion were more resistant to the general competitive effects of Centaurea, the root exudates from Centaurea, and to a chemical specific to the root exudates of Centaurea (±)-catechin.
  • 4Although these results may be confounded by maternal effects, they provide initial evidence that native plant species may evolve to tolerate the effects of an exotic invader, and in particular an invader's novel allelochemistry.
  • 5Such effects may have long-term implications for plant invasions and the organization of plant communities. Evolved tolerance may ultimately contribute to coexistence among natives and invaders, with our results suggesting that natural plant communities may be more coevolved and less individualistic than currently thought.

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