9310992 Marquis Models that predict the optimal defense 'strategy' that plants should evolve to combat potential herbivores have assumed a cost of defense. However, there is no general agreement as to whether costs of defense exist or in what form they may be manifested. This research will document the presence or absence of costs associated with the production of a specific group of defensive chemicals (glucosinolates or mustard oils) in Brassica rapa. This will be done using artificial selection experiments. By selecting populations of B. rapa for glucosinolate content, costs of defense and the form in which they are manifested can be documented by examining the effects of this selection on other, non-selected characters. Potential costs will be looked for in the form of reduced plant survival, growth, and reproduction, leaf tannin content, leaf hairiness, and ability to tolerate herbivore damage. Further, the consequences this selection has for realized resistance against a specialist (Pieris rapae) and a generalist (Trichoplusia ni) herbivore will also be examined. %%% Elucidation of the costs associated with defense is important to basic science in that it will help us to determine how and when the evolutionary response of plants to selection imposed by herbivores may be constrained. In addition it is important to applied science, because herbivores are major pests of agriculture, forestry and horticulture. The most common method used to control their damage is the application of chemical pesticides, which can have serious environmental consequences. Understanding the evolution of defenses in plant s can help us determine when breeding herbivore resistant plants is economically practical, thereby decreasing our reliance on chemical pesticides. *** F G H I J K L M N O P Q S T U V W X _ ` a b c d f g h i j k m n o p q r s t u v w x y z { 9310992 Marquis Models that predict the optimal defense 'strategy' that plants should evolve to combat potential herbivores A I J N w } ~ ! ! !f ! F ( Times New Roman Symbol & Arial " h + e+ e X Abstract Dissertation Research Elizabeth M. Behrens Elizabeth M. Behrens
