Oecologia DOI 10.1007/s00442-006-0496-y 123 PLANT ANIMAL INTERACTIONS A Weld test of the directed deterrence hypothesis in two species of wild chili Douglas J. Levey · Joshua J. Tewksbury · Martin L. Cipollini · Tomás A. Carlo Received: 15 December 2005 / Accepted: 27 June 2006  Springer-Verlag 2006 Abstract The directed deterrence hypothesis posits that secondary metabolites in ripe fruit function to deter fruit consumption by vertebrates that do not dis- perse seeds, while not impacting consumption by those that do. We tested this hypothesis in two species of wild chilies (Capsicum spp.). Both produce fruits that contain capsaicinoids, the compounds responsible for the pungency of chilies. Previous work suggests seed- dispersing birds but not seed-destroying rodents con- sume chili fruits, presumably because rodents are deterred by capsaicin. However, fruit removal from chili plants by rodents and other mammals has not been previously explored. Because laboratory rodents can develop a preference for capsaicin, it is quite possi- ble that wild rodents are natural consumers of chili fruits. We monitored the fate of 125 marked fruits of Capsicum chacoense and 291 fruits of Capsicum ann- uum. For both species, essentially all fruit removal occurred during the day, when rodents are inactive. Video monitoring revealed fruit removal only by birds, mostly by species known to disperse chili seeds in viable condition. Furthermore, these species are from taxonomic groups that tend to specialize on lipid-rich fruits. Both species of chili produce fruits that are unusually high in lipids (35% in C. chacoense, 24% in C. annuum). These results support the directed deter- rence hypothesis and suggest that fruiting plants distin- guish between seed predators and seed dispersers by producing fruits that repel the former and attract the latter. Keywords Birds · Capsaicin · Chili · Directed deterrence · Fruit Introduction Many of the most intricate and fundamental interac- tions between plants and their consumers are mediated by secondary metabolites, compounds with no known physiological role in the plants that produce them (Bernays and Chapman 1994; Coley and Barone 1996; Adler et al. 2001). In seeds, leaves, and unripe fruit, the primary function of secondary metabolites is to deter consumption by granivores and herbivores. In ripe fruits, their function is more complex because fruit consumption can be either beneWcial or detrimental to plants, depending on whether the consumer disperses or destroys seeds. Thus, fruiting plants face the evolu- tionary challenge of packaging their seeds in pulp with compounds that simultaneously attract seed-dispersing frugivores and deter seed-destroying frugivores (Jan- zen 1977; Herrera 1982; Cipollini 2000). The directed deterrence hypothesis (Cipollini and Levey 1997b) posits that some plant species have met this challenge through the production of secondary metabolites that are inhibitory toward organisms that are likely to Communicated by Phyllis Coley D. J. Levey (&) Department of Zoology, University of Florida, 118525, Gainesville, FL 32611-8525, USA e-mail: dlevey@zoo.uX.edu J. J. Tewksbury · T. A. Carlo Department of Biology, University of Washington, Seattle, WA 98115, USA M. L. Cipollini Department of Biology, Berry College, 430, Mount Berry, GA 30149-0439, USA