Date Approved

2005

Degree Type

Open Access Senior Honors Thesis

Department

Biology

First Advisor

Dr. Gary Hannan

Second Advisor

Dr. James Vandenbosch

Abstract

Mercurialis annua is an androdioecious plant species, meaning populations may contain both male and cosexual individuals. It is able to modify resource allocation to male and female function in varying conditions, such as light and competition regimes. One component of resource allocation may involve changes in the relative timing of production of male and female flowers. A controlled greenhouse experiment was performed to test for the effects of shading on the production of male and female flowers in four populations. Evidence suggested that plants grown in shade would be relatively less female than those grown in the sun. Although the average number of day to the production of male versus female flowers did not show a response to shading, the number of plants producing male versus female flowers during early development differed between light treatments. The shade treatment induced a reduction in number of plants producing female flowers, as predicted by my hypothesis. The populations differed in their specific responses to shading, suggesting that populations have adapted individually to local selective pressures.

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