Pathogens and cancers can evolve on very short timescales within our bodies. This rapid evolution enables these populations to develop their most dangerous traits: aggressive growth, resistance to drugs, and the ability to escape our immune systems or invade new parts of the body. Alison Feder studies these evolutionary pathways using clinically derived genomic sequencing data and novel computational methods and models. By understanding both genetic and environmental drivers of pathogen and cancer evolution within their hosts, the Feder lab hopes to discover new ways to interfere with disease progression.