Brown rats (also known as Norway or sewer rats) are one of the most common mammals in the world, and cause significant damage to human health and infrastructure. Cities in particular harbor very large rat populations, but their biology is poorly known. This study will address novel and important questions about the evolutionary and ecological processes occurring in the built environment using the infamous rat population in New York City. What specific types of urban infrastructure, such as sewers or subways, do rats use to move through the city? Are rat movements associated with socioeconomics of human neighborhoods? Where did NYC rats come from, and how are they related to other populations around the world? How have rats evolved since they invaded NYC in the 18th century? Results from this project will also be used to introduce students and the public to evolutionary biology by funding art projects and innovative curricular materials.<br/><br/>Several complementary genomic approaches will be used to understand the evolution of brown rats from local to global scales. First, landscape modeling based on structural and socioeconomic characteristics of NYC will shed light on the drivers of local population structure and movements of rats within NYC. Next, signatures of historical population size changes and ancestry that are encoded in the genomes of rats from around the world will then be examined. Within NYC, genes involved in recent adaptation to the urban environment will also be identified. Finally, these evolutionary changes will be confirmed using DNA extracted from museum specimens of rats collected over the last 125 years.