ARS | Publication request: Headspace volatiles from 52 oak species advertise induction, species identity, and evolution, but not defense

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 2012
Publication Date: December 22, 2012
Repository URL: http://link.springer.com/article/10.1007%2Fs10886-012-0224-5
Citation: Pearse, I.S., Gee, W.S., Beck, J.J. 2012. Headspace volatiles from 52 oak species advertise induction, species identity, and evolution, but not defense. Journal of Chemical Ecology. 39(1):90-100.

Interpretive Summary: Odors emitted by leaves convey general information about a plant to other organisms in their proximity. Despite interest in understanding the relevance of odors emitted for particular ecological interactions, there has been relatively little effort to assess generally what information these odors are transmitting. We surveyed the odor profiles of wounded and unwounded leaves of 52 oak (Quercus) species. We compared the evolutionary relationship (phylogenetics) between the studied oak species to assess in what circumstances the individual oak trees advertised their species identity, taxonomic affiliation (similar characteristics), direct defenses, or damage. We found that the species’ identity in addition to its characteristic similarities were advertised when leaves were wounded, but the species could not be differentiated by odor when leaves were not wounded. Various fatty-acid derivative compounds showed the strongest phylogenetic signal suggesting that they may best disclose taxonomic affiliations in oaks. We tested whether oak volatile composition or diversity advertised high defensive investment, but we found no evidence for this. Wounded leaves disclose much about an oak species’ identity and taxonomic affiliation, but unwounded leaves do not. This is consistent with the idea that volatile information is targeted toward natural enemy recruitment.

Technical Abstract: Leaf volatiles convey public information about a plant to other organisms in their proximity. Despite the deep interest in understanding the relevance of volatile emissions for particular ecological interactions, there has been relatively little effort to assess generally what information volatile profiles transmit. We surveyed the volatile profiles of wounded and unwounded leaves of 52 oak (Quercus) species. We used phylogenetic comparison and multivariate techniques to assess in what circumstances oak individuals advertised their species identity, taxonomic affiliation, direct defenses, or damage. We found that the species’ identity in addition to its taxonomic affiliation was advertised when leaves were wounded, but the species could not be differentiated by odor when leaves were not wounded. Various fatty-acid derivative compounds showed the strongest phylogenetic signal suggesting that they may best disclose taxonomic affiliations in oaks. We tested whether oak volatile composition or diversity advertised high defensive investment, but we found no evidence for this. Wounded leaves disclose much about an oak species’ identity and taxonomic affiliation, but unwounded leaves do not. This is consistent with the idea that volatile information is targeted toward natural enemy recruitment.