DISSERTATION RESEARCH: The Genetic Architecture and Evolution of Phenotypic Plasticity for Chemical Defenses in a Wild Plant

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Many complex traits?those controlled by multiple genes?are often influenced by the environment, a phenomenon called phenotypic plasticity. In many cases, the relative importance of genes and environment (i.e., ?nature? and ?nurture?) is unclear. Furthermore, species, populations, and individuals often differ in their sensitivity to various environmental cues. Theoretical work has shown that such genetic variation for plasticity should have profound implications for the evolution of complex traits in complex environments. However, both the adaptive value of plasticity and the genes underlying plastic responses are poorly understood, largely due to a lack of empirical research on the subject. This project will measure natural selection on plasticity of glucosinolates, an important chemical defense against insect herbivores, in a wild herb. Glucosinolates and reproductive fitness will be measured in multiple lineages planted in four natural habitats and a variety of controlled conditions in the greenhouse. The PIs will then map genomic regions containing genes that affect the response of glucosinolate content to various environmental stimuli.The ?nature vs. nurture? debate is not only fundamental to the field of evolutionary genetics, but also directly relevant to current research in applied fields such as agriculture, medicine, and biodiversity conservation. Examples of partially plastic complex traits include crop pest resistance, human susceptibility to diseases such as cancer, and wildlife health and behavior. Understanding the genetic architecture and the evolutionary significance of plasticity will be especially important as the natural world adapts to a rapidly changing climate. Training of students will occur.