9317424 Thompson This research examines the geographical variation in the ecological relationships between Greyia moths and their host plants in the plant family Saxifragaceae. There is considerable geographic variation in the degree of mutualism vs. exploitation in the moths' relationship with their usual host plant (Lithophragma) and in switching over to an alternative saxifragaceous host, Heuchera. This geographic variation is used to address the origins of host switching and how mutualisms are derived from antagonisms and vice versa. The three objectives of this research are to determine whether: 1) Heuchera-feeding Greyia politella populations are genetically differentiated from Lithophragma-feeding populations, 2) host shifts are associated with plant chromosome number, and 3) the host shift to Heuchera has resulted in a mutualistic relationship. %%% Geographic variation in plant-insect relationships has been largely ignored in previous studies. Such variation provides important clues into how mutualistic and antagonistic relationships between organisms originate and change with time. This project is novel in addressing important questions about the origins of antagonisms and mutualisms between insects and their host plants and in examining the geographic variation in these relationships. Information from this research could have important applications to biological control and other pest management methods in agriculture and forestry. ***
