Affiliation: | a Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221-0006, U.S.A. b Fairchild Tropical Garden, 10901 Old Cutler Road, Miami, FL 33156, U.S.A. c Department of Chemical Ecology, Göteborg University, Reutersgatan 2C, S-413 30, Göteborg, Sweden d Department of Biology, Tulane University, New Orleans, LA 70118, U.S.A. |
Abstract: | The chemistry of the volatile emissions of male cones of four putatively insect-pollinated cycad (Cycadales) species and cones of both sexes of one wind-pollinated cycad species was analysed using GC-MS Zamia furfuracea, Macrozamia moorei, and Encephalartos altensteinii had blends consisting primarily of monoterpenoids, benzenoids, and in two causes, a di-unsaturated aliphatic hydrocarbon, while that of Zamia pumila was dominated by methyl salicylate, with sesquiterpenes and aliphatic hydrocarbons also present. In contrast, the wind-pollinated Cycas rumphii contained a series of highly alcohols, ketones and esters. The compounds classes found in the cycads are potent herbivore deterrents, and there is no apparent difference in this regard between insect- and wind-pollinated species. The results suggest convergent evolution in the gymnospermous cycads and magnoliid angiosperms of the olfactory cues that attract pollinating insects; the data are consistent with the hypothesis that early chemical attractants for pollinators evolved from herbivore deterrents. |