Dissertation Research: Ecological and Evolutionary Constraints to Herbivore Resistance in a Native Plant - Mulitiple Herbivore Community

Duke University, Durham NC

Investigators

Abstract

0073176 Rausher While physical and chemical defenses provide plants with immunity from nearly all of the potential natural enemies in their environment, most plants are still attacked by a community of herbivores that are able to overcome these defenses. A major question in evolutionary ecology is what prevents plants from evolving improved resistance to herbivory. The thesis of this research is that there are potential constraints on the evolution of resistance that are revealed only by examining the entire community of herbivores that feed on a host plant. Through a series of field experiments using the insect herbivore community of horsenettle (Solanum carolinense), this research will investigate these constraints by assessing genetic variation for resistance, characterizing natural selection acting on resistance, and investigating the ecological interactions among the insects and their host plant. This research addresses basic scientific questions regarding plant-herbivore coevolution and the nature of potential competition among plant-eating insects. In addition, horsenettle is an economically important weed, and its close kinship with a number of crop species enables it to act as a reservoir for a number of crop pests. Therefore, this research will also provide information that is of interest to weed control and pest management programs.