Environmental microbiology is at an important crossroads. Over the last twenty years we have learned that microbes are the most ubiquitous organisms on Earth, yet the dynamics that govern their interactions and evolution remain poorly understood. What is the role of individual populations within the community? What is the range of genomic similarity that defines a population as a functional unit? What mechanisms govern diversification of microbial populations in the environment?

We address these questions using a combination of quantitative molecular approaches, genomics, physiology, and modeling. Our primary model system is the coastal ocean where we study patterns of diversity among co-occurring bacterioplankton from the level of the entire community to the individual genome. For the latter, we focus on bacteria of the genus Vibrio, which are longstanding models of heterotrophic, marine bacteria and also contain many pathogenic variants (e.g., V. choleraeV. vulnificus). As part of the Woods Hole Center for Oceans and Human Health (COHH), we are also exploring environmental and evolutionary mechanisms that trigger the emergence of pathogenic variants within the vibrios.  We are also part of the Earth Systems Initiative and the Microbial Systems Group at MIT.