Thomas Bentley
Published: 2014
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Plant volatiles mediate many important interactions, including plant-predator interactions, plant-herbivore interactions, plant-pollinator interactions, and plant-plant interactions. Plant volatiles can attract predators to prey, repel ovipositing herbivores, attract pollinators, coordinate a plant's defenses, communicate with other plants, and act as foraging cues. As our knowledge of the diversity and complexity of plant volatile signaling grows, we should view plant volatiles from an ecological perspective informed by signaling theory. This theoretical framework will provide insight into the evolutionary pressures involved in plant volatile communications. This approach will also generate predictions about features that may be found in plant volatile signaling, including mimicry, costly signaling, aposematic signaling, and kin selection. This dissertation investigates three plant communication systems with this approach. In one study, I studied the effects of inbreeding on floral volatile signaling and pollinator interactions in horsenettle. I found that inbreeding negatively affects plant-pollinator signaling through floral volatiles and affects pollinator behavior. This is an example of ecologically mediated inbreeding depression caused by a breakdown of volatile communication. In another study, I investigated the possibility of plant-plant communication in horsenettle in preparation for studying kin selection in plants, though the evidence for plant-plant volatile communication in this study was not straightforward. Lastly, I investigated honest versus dishonest signaling in three species of tobacco and found evidence for a plant that honestly signals its defensive status, providing evidence for aposematic signaling through volatile emissions. This dissertation explores the consequences of diversity on volatile communication, on both the interspecific and intraspecific level, as well as the utility of evolutionary and ecologically motivated study of plant volatile communication.