Biological Invasions

, Volume 9, Issue 6, pp 715–722 | Cite as

Rapid shifts in the chemical composition of aspen forests: an introduced herbivore as an agent of natural selection

  • Joseph K. BaileyEmail author
  • Jennifer A. Schweitzer
  • Brian J. Rehill
  • Duncan J. Irschick
  • Thomas G. Whitham
  • Richard L. Lindroth
Original Paper


The global ecological impacts of introduced and exotic species can be dramatic, leading to losses in biodiversity and ecosystem “meltdown”, however, the evolutionary impacts of introduced species are much less understood. Further, very few studies have examined whether mammalian herbivores can act as agents of natural selection for plant traits. We examined the hypothesis that variation in aspen phytochemistry resulted in selective herbivory by Cervus elaphus (elk), an introduced mammalian herbivore. With the experimental removal of a large elk exclosure, elk selectively eliminated 60% of an aspen population previously protected from herbivory resulting in a dramatic shift in the phytochemical composition of the aspen forest. Selection gradients (β) varied from 0.52 to 0.66, well above average relative to other studies of selection. These results indicate that introduced herbivores can have rapid evolutionary consequences even on long lived native species. Because there are fundamental links between phytochemistry, biodiversity and ecosystem processes, the effects of an introduced herbivore are likely to have cascading impacts on the services ecosystems provide.


Aspen Elk Herbivory Introduced species Natural selection Phytochemistry Populus Plant animal interactions 



Special thanks to Christy Grow and James Andrade for help in the field. Thanks to John Stinchcombe for helpful comments on the manuscript. This research was supported by National Science Foundation Integrative Research Challenges in Environmental Biology and Frontiers in Integrative Biological Research grants. A grant from the National Science Foundation (IOB 0421917) supported D. Irschick.


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Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • Joseph K. Bailey
    • 1
    • 2
    • 4
    Email author
  • Jennifer A. Schweitzer
    • 1
    • 3
    • 4
  • Brian J. Rehill
    • 5
  • Duncan J. Irschick
    • 6
  • Thomas G. Whitham
    • 2
    • 4
  • Richard L. Lindroth
    • 7
  1. 1.Department of Ecology and Evolutionary BiologyUniversity of TennesseeKnoxvilleUSA
  2. 2.Department of Biological SciencesNorthern Arizona UniversityFlagstaffUSA
  3. 3.School of ForestryNorthern Arizona UniversityFlagstaffUSA
  4. 4.Merriam-Powell Center for Environmental ResearchNorthern Arizona UniversityFlagstaffUSA
  5. 5.Department of ChemistryUnited States Naval AcademyAnnapolisUSA
  6. 6.Department of BiologyUniversity of MassachusettsAmherstUSA
  7. 7.Department of EntomologyUniversity of WisconsinMadisonUSA

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