INTEGRATION OF CHEMICAL INFORMATION: THE ROLE OF PLANT CHEMISTRY MEDIATING INTERACTIONS FROM THE INDIVIDUAL TO THE COMMUNITY LEVEL

Abstract

Plants produce a large diversity of secondary metabolites that are increasingly understood to be important in the mediation of interactions with other organisms. The field of Chemical Ecology treats these interaction-mediating compounds as information that can be utilized by all organisms able to perceive and interpret it. For plants, this ubiquitous availability of chemical information can be compromising because the same info chemicals can, at the same time, function to attract mutualists, while they also have to function to minimize interactions with antagonists, such as competitors, herbivores, and pathogens. In this thesis, I first present a review of the evidence on such a plant chemistry-mediated ecological conflict; herbivory-induced changes in plant secondary metabolism and chemical resistance compromising interactions with pollinators. Then I use a case study from an Ericaceae shrub, Becharia resinosa, growing in endangered High Andean Forest habitats, to investigate interactions between florivores, nectar robbers, and pollinators mediated by a rare floral chemical trait, petal stickiness. Finally, I use a chemical information model system, the tall goldenrod, Solidago altissima, to study the integration of different types of environmental information used by the plant to affect the outcome of ecological interactions. Specifically, I study the perception of reduced red: far-red light ratios as a cue for competition and the perception of herbivore damage, to understand how plants integrate spectral and chemical environmental information. In addition, I show evidence that a plant’s perception of competitive neighborhood alters the perception and processing of chemical information encoded in volatile organic compounds from neighboring plants. All these studies have in common that they suggest that the outcome of ecological interactions mediated by chemical information strongly varies with the environmental context in which they are played out and how the information is utilized by the interacting players.