This proposal focuses on the generation, control, and exploitation of diversity in biology. Genetic diversity drives the evolution of organisms, hinders cures of cystic fibrosis, AIDS and cancer, plays a crucial role in bacterial and fungal infections, and accounts for individual differences in susceptibility to disease agents and the responses to drugs. Non-.genetic diversity allows different cells to respond differently to the same environment, differences that can increase the infectivity of pathogens and their resistance to antibiotics. This team will use experiment and theory to study the origin and consequences of biological diversity over scales of size and time that range from the folding of individual proteins to the formation of new species. The core of the proposal is the group of Bauer fellows, young interdisciplinary scientists who come from a variety of backgrounds and interact to form a single collaborative community that nucleates interactions amongst a wide range of research groups.