Evolution of signal emission by uninfested plants to help nearby infested relatives
Herbivory by arthropods often induces the emission of plant volatiles, which attract natural enemies of the herbivores. This induced emission of volatiles is considered to be a strategy of plants to effectively defend against herbivores by employing bodyguards. Recent empirical research has revealed that these volatiles can also affect neighboring undamaged plants and cause them to emit volatiles secondarily. Provided that signal emission imposes some cost on plants, the evolutionary advantage to undamaged plants in the emission of such secondary signals is unclear. We hypothesized that plants have evolved to emit a secondary signal to help nearby relatives by promoting the recruitment of natural enemies, whereby they increase inclusive fitness. We constructed a simulation model to evaluate this hypothesis. Our simulations suggest that a secondary signal evolves if the following five conditions are met: the cost of the signal is low; the potential risk of infestation is high; the attractiveness of the signal to natural enemies is highly positively correlated with the local density of the signal chemical; dispersal of offspring is spatially restricted, causing population viscosity, and; sufficient vacant space is available, allowing the population to be elastic.
KeywordsAltruism Eavesdropping HIPV Kin selection SOS signal Talking plants Viscous population Elasticity
We thank K. Kikuzawa, T. Ohgushi, J. Takabayashi, A. Yamauchi, and many other researchers at Center for Ecological Research, Kyoto University for valuable discussions. We also thank Andy Gardner and an anonymous reviewer for various kind and helpful comments. This work was partly supported by a Grant-in-Aid for JSPS Fellows and by the Grant for the Biodiversity Research of the 21st Century COE (A14).
- Birkett MA, Campbell CAM, Chamberlain K, Guerrieri E, Hick AJ, Martin JL, Matthes M, Napier JA, Pettersson J, Pickett JA, Poppy GM, Pow EM, Pye BJ, Smart LE, Wadhams GH, Wadhams LJ, Woodcock CM (2000) New roles for cis-jasmone as an insect semiochemical and in plant defense. Proc Natl Acad Sci USA 97:9329–9334PubMedCrossRefGoogle Scholar
- Dicke M (1999) Evolution of induced indirect defense of plants. In: Tollrian R, Harvell CD (eds) The ecology and evolution of inducible defenses. Princeton University Press, Princeton NJ, pp 62–88Google Scholar
- Dicke M, Vet LEM (1999) Plant-carnivore interactions: evolutionary and ecological consequences for plant, herbivore and carnivore. In: Olff H, Brown VK, Drent RH (eds) Herbivores: between plants and predators. Blackwell Science, Oxford UK, pp 483–520Google Scholar
- Sabelis MW, van Baalen M, Bakker FM, Bruin J, Drukker B, Egas M, Janssen ARM, Lesna IK, Pels B, Van Rijn P, Scutareanu P (1999) The evolution of direct and indirect plant defence against herbivorous arthropods. In: Olff H, Brown VK, Drent RH (eds) Herbivores: between plants and predators. Blackwell Science, Oxford UK, pp 109–166Google Scholar
- Sabelis MW, van Baalen M, Pels B, Egas M, Janssen A (2002) Evolution of exploitation and defense in tritrophic interactions. In: Dieckmann U, Metz JAJ, Sabelis MW, Sigmund K (eds) Adaptive dynamics of infectious diseases: in pursuit of virulence management. Cambridge University Press, Cambridge, pp 297–321Google Scholar