Three connecting themes that run through all aspects of our research are evolution, cell biology, and symbiosis. We are particularly fascinated by the origin and evolution of the eukaryotic cell and its endosymbiotic organelles, mitochondria and plastids, but we also focus on numerous other (more recent) symbiotic interactions among bacteria, archaea, single-celled eukaryotes, and animals. We try to understand how these symbioses originate, how they are maintained at the cellular level for over hundreds of millions of years, and how they eventually become either organelles or extinct. We use a variety of interdisciplinary approaches to study these complex symbiotic systems in the field, in the lab, and with computational methods. Our ultimate goal is to bridge the gap between multiple fields that rarely interact with each other and to fully understand how an intracellular organism becomes so highly incorporated into its host cell that it becomes a part of the cell, an organelle.