, Volume 181, Issue 3, pp 905–910 | Cite as

Gut passage and secondary metabolites alter the source of post-dispersal predation for bird-dispersed chili seeds

  • Evan C. Fricke
  • David C. Haak
  • Douglas J. Levey
  • Joshua J. Tewksbury
Plant-microbe-animal interactions - original research


Plants can influence the source and severity of seed predation through various mechanisms; the use of secondary metabolites for chemical defense, for example, is well documented. Gut passage by frugivores can also reduce mortality of animal-dispersed seeds, although this mechanism has gained far less attention than secondary metabolites. Apart from influencing the severity of seed predation, gut passage may also influence the source of seed predation. In Bolivia, we compared impacts of these two mechanisms, gut passage and secondary metabolites, on the source of seed predation in Capsicum chacoense, a wild chili species that is polymorphic for pungency (individual plants either produce fruits and seeds containing or lacking capsaicinoids). Using physical exclosures, we isolated seed removal by insects, mammals, and birds; seeds in the trials were from either pungent or non-pungent fruits and were either passed or not passed by seed-dispersing birds. Pungency had little influence on total short-term seed removal by animals, although prior work on this species indicates that capsaicin reduces mortality caused by fungi at longer time scales. Gut passage strongly reduced removal by insects, altering the relative impact of the three predator types. The weak impact of pungency on short-term predation contrasts with previous studies, highlighting the context dependence of secondary metabolites. The strong impact of gut passage demonstrates that this mechanism alone can influence which seed predators consume seeds, and that impacts of gut passage can be larger than those of secondary metabolites, which are more commonly acknowledged as a defense mechanism.


Frugivory Granivory Chemical defense Mutualism Seed fate 



We thank Uco Sapag Ruta, Don Odon, and many others for field assistance. This research was supported by National Science Foundation grant DEB 0129168 (to D. L. and J. T.), National Geographic Society grants (to J. T. and D. L.), and a National Science Foundation Graduate Research Fellowship (to E. F.). Logistical support in Bolivia was provided by Fundación Amigos de la Naturaleza and the Wildlife Conservation Society.

Author contribution statement

D. L., J. T., and D. H. designed the experiments. J. T. and D. H. conducted the field experiments. E. F. performed the statistical analyses and wrote the first draft of the manuscript. All authors revised the manuscript.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Evan C. Fricke
    • 1
  • David C. Haak
    • 2
  • Douglas J. Levey
    • 3
  • Joshua J. Tewksbury
    • 4
    • 5
    • 6
  1. 1.Department of Ecology, Evolution, and Organismal BiologyIowa State UniversityAmesUSA
  2. 2.Department of Plant Pathology, Physiology, and Weed ScienceVirginia Polytechnic Institute and State UniversityBlacksburgUSA
  3. 3.Division of Environmental BiologyNational Science FoundationArlingtonUSA
  4. 4.Colorado Global Hub, Future EarthBoulderUSA
  5. 5.Sustainability, Energy and Environment ComplexUniversity of ColoradoBoulderUSA
  6. 6.School of Global Environmental StudiesColorado State UniversityFort CollinsUSA

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