Oecologia

, Volume 146, Issue 3, pp 404–414

Enemy release but no evolutionary loss of defence in a plant invasion: an inter-continental reciprocal transplant experiment

  • Benjamin J. Genton
  • Peter M. Kotanen
  • Pierre-Olivier Cheptou
  • Cindy Adolphe
  • Jacqui A. Shykoff
Plant Animal Interactions

DOI: 10.1007/s00442-005-0234-x

Cite this article as:
Genton, B.J., Kotanen, P.M., Cheptou, PO. et al. Oecologia (2005) 146: 404. doi:10.1007/s00442-005-0234-x

Abstract

When invading new regions exotic species may escape from some of their natural enemies. Reduced top–down control (“enemy release”) following this escape is often invoked to explain demographic expansion of invasive species and also may alter the selective regime for invasive species: reduced damage can allow resources previously allocated to defence to be reallocated to other functions like growth and reproduction. This reallocation may provide invaders with an “evolution of increased competitive ability” over natives that defend themselves against specialist enemies. We tested for enemy release and the evolution of increased competitive ability in the North American native ragweed (Ambrosia artemisiifolia: Asteraceae), which currently is invading France. We found evidence of enemy release in natural field populations from the invaded and native ranges. Further we carried out a reciprocal transplant experiment, comparing several life history traits of plants from two North American (Ontario and South Carolina) and one French population in four common gardens on both continents. French and Canadian plants had similar flowering phenologies, flowering earlier than plants from further south in the native range. This may suggest that invasive French plants originated from similar latitudes to the Canadian population sampled. As with natural populations, experimental plants suffered far less herbivore damage in France than in Ontario. This difference in herbivory translated into increased growth but not into increased size or vigour. Moreover, we found that native genotypes were as damaged as invading ones in all experimental sites, suggesting no evolutionary loss of defence against herbivores.

Keywords

Ambrosia artemisiifolia Bioinvasion Herbivory Plant defence Weed 

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Benjamin J. Genton
    • 1
  • Peter M. Kotanen
    • 2
  • Pierre-Olivier Cheptou
    • 3
  • Cindy Adolphe
    • 3
  • Jacqui A. Shykoff
    • 1
  1. 1.Laboratoire Ecologie, Systématique et Evolution, UMR CNRS-UPS-ENGREF 8079Université Paris-SudOrsay cedexFrance
  2. 2.Department of BotanyUniversity of Toronto at MississaugaMississaugaCanada
  3. 3.UMR 5175 CEFE - Centre d’Ecologie Fonctionnelle et Evolutive (CNRS)Montpellier cedex 05France