PIs are Richard DiGiulio, Caren Weinhouse, and Nishad Jayasundara, Duke University. Atlantic killifish populations that have adapted to environmental pollution are a classic example of the emerging field of evolutionary toxicology. The killifish in the Elizabeth River, Virginia, have evolved remarkable resistance to toxic effects of high levels of industrial pollution. An important detoxification gene is nonresponsive to pollution in adapted fish, but becomes more sensitive to pollution in later generations, implying that this gene’s behavior is not due entirely to irreversible genetic change. This project will test the hypothesis that reversible epigenetic changes underlie this progressive loss of resistance in pollution-adapted killifish in the Elizabeth River. We will test a range of epigenetic marks that might control the behavior of this gene. Our findings will provide important insights into the role of epigenetic changes as an effective strategy in generational response to chemical exposure and rapid adaptation to radical environmental change.