Plant Ecology

, Volume 213, Issue 6, pp 945–954

Decreased indirect defense in the invasive tree, Triadica sebifera

  • Juli Carrillo
  • Yi Wang
  • Jiangqing Ding
  • Kyle Klootwyk
  • Evan Siemann
Article

Abstract

In the absence of coevolved natural enemies, plants are expected to experience selection away from costly herbivore defenses toward growth and reproduction [evolution of increased competitive ability hypothesis (EICA)], yet no one has demonstrated EICA for an indirect defense trait. Likewise, we have little understanding of how constitutive and induced levels of defense vary among native and invasive plant populations. We conducted a greenhouse experiment in the introduced range to test whether invasive populations have reduced constitutive and induced investment in an indirect defense trait, extrafloral nectar (EFN) production, compared to native populations of Chinese tallow tree, Triadica sebifera, through an experimental leaf damage treatment. Overall, native populations invested more in indirect defense: Native populations had a greater number (+16 %) and percentage of leaves producing EFN (35 vs. 28 %), produced more EFN (63 % greater volume), and produced more sugar (+33 %) compared to invasive populations, independent of damage treatment. Of these traits, number of leaves producing EFN and volume of EFN exhibited a trade-off between constitutive and induced investment but these did not depend on plant origin. Our results are the first to support the EICA hypothesis for an indirect defense trait. This suggests that tri-trophic interactions such as indirect defense are under similar selection as direct defense traits within introduced populations. Despite reduced investment in EFN production, invasive populations still retain the ability to produce EFN, which may enable invasive plants to defend against herbivores in the introduced range.

Keywords

Evolution of increased competitive ability (EICA) Extrafloral nectar (EFN) Exotic species Tallow tree Trade-offs 

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Juli Carrillo
    • 1
  • Yi Wang
    • 2
  • Jiangqing Ding
    • 2
  • Kyle Klootwyk
    • 1
  • Evan Siemann
    • 1
  1. 1.Department of Ecology and Evolutionary BiologyRice UniversityHoustonUSA
  2. 2.Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Institute/Wuhan Botanical GardenChinese Academy of SciencesWuhanChina

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