The Role of Herbivores in the Evolution of Dioecy from Gynodioecy

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A central problem in plant biology is understanding when and how separate sexes evolve from hermaphroditism. Recent research has pin-pointed the environment as an important element mediating this transition, however, little attention has been paid to the enemy dimension of the environment. The objective of this research is to evaluate the role of herbivory in the evolution of separate sexes from hermaphroditism using the wild strawberry and it's flower bud clipping herbivore as a model system. This research will test a long standing hypothesis for how male-biased herbivory could facilitate the evolution of separate genders as well as four newly developed hypotheses for how herbivory could impede this transition. These hypotheses will be tested using a combination of greenhouse and experimental garden studies. Herbivore levels will be manipulated and fitness through male and female function will be measured. These studies will be complemented by direct measures of the response to selection.This work will expand our understanding of the plant-animal interactions governing the evolution of separate genders to include enemies. In doing so, it will provide some of the first data on the role of antagonists in breeding system evolution. Moreover, because this study utilizes a wild relative of an agricultural species and one of its most damaging pests, data gathered on resistance and tolerance in this system will be relevant to development of alternatives to pesticide use in managed settings.