DISSERTATION RESEARCH: Genetic and Ecological Bases of Hostplant Specialization.

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The genetic basis of complex traits that help organisms adapt to their environment is not well understood for any organism. The basis of such traits is particularly fascinating when closely related species differ in adaptation to their environment. Heliothis subflexa and Heliothis virescens are one such species pair: recently evolved from a shared ancestor, they are 99% genetically similar. In spite of this genetic similarity, they differ radically in the number and diversity of hostplants fed upon. Heliothis subflexa is monophagous, feeding only on Physalis plants, while Heliothis virescens is a dietary generalist, feeding on 14 plant families. The goal of this proposal is to determine whether use of Physalis plants by the generalist Heliothis virescens is controlled by the same chromosomes as in Heliothis subflexa, and whether selection for use of Physalis contributes to macroevolutionary divergence. Ecologically important traits can affect both basic biological phenomena (e.g., speciation) and higher level interactions between species (e.g., the impact of insect pests on agricultural production). An improved understanding of their genetic bases could have profound impact on our understanding of the relationship between adaptation and speciation. In addition, clarification of the genetic mechanisms underlying insect hostplant range could lead to novel ways of controlling agriculturally important pest species.