Conflict of Interest? Investigating the Costs and Benefits of Herbivore Defense Using the Model Plant Boechera Stricta.

Undergraduate #56
Discipline: Ecology Environmental and Earth Sciences
Subcategory: Ecology

John Poole - University of Arkansas Little Rock
Co-Author(s): Lauren Carley, Duke University, Durham, North Carolina; Tom Mitchell-Olds, Duke University, Durham, North Carolina

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Boechera stricta, a native forb common to the Rocky Mountain range in western North America, is a model species at the forefront of genetics and ecology. Over millennia, in response to herbivory, plants have developed secondary metabolite defensive compounds to deter wide ranges of herbivores. Glucosinolates represent one such type of compound produced by Brassicaceous plants. However, glucosinolates may act as cues for oviposition for specialist herbivores and thus may lead to a conflict of interest for their host plant. This study focuses on whether contrasting glucosinolate chemical profiles confer costs or benefits to overall fitness in relation to defense against specialist herbivores. I combined field observations from two separate studies to infer whether glucosinolate chemical profile influences specialist oviposition and feeding behavior, and if this behavior may result in selection for plant chemistry, thus influencing phenotypic diversity in defensive strategy. Overall, I found that there was no significant response in specialist oviposition or abundance based on chemical profile. However, in natural populations of B. stricta, plants on which the specialist herbivore Euchloe ausonides were present had significantly higher levels of herbivore damage to fruits than plants on which the specialist was absent. These results indicate that plants that attract specialist herbivores suffer a reproductive disadvantage, but that host plant chemical profile alone does not appear to influence that attraction. Factors specifically influencing specialist herbivore oviposition, presence/absence, and abundance remain unknown.

Funder Acknowledgement(s): The National Science Foundation directly funded my project, and the National Institute of Health funded the Mitchell-Olds lab group's previous projects, of which I was able to use supplemental data from.

Faculty Advisor: Dr. Janet Lanza, jxlanza@ualr.edu

Role: This research was performed at the Rocky Mountain Biological Laboratory over the summer of 2017. As part of an NSF funded REU, I was able to design and perform the entirety of the research and analysis of this project. I was able to meet with my mentor two to three times a week for advice and guidance as well as assistance with draft proposal and final paper submission.