Epistasis and evolution

How does the cell respond to genetic perturbations, and how do perturbations combine with each other to affect phenotype? We study the effects of single and double perturbations (e.g., deletions) of metabolic enzyme genes in the yeast S. cerevisiae. Deviation from expected effects in the double perturbations give rise to epistatic interactions, producing system-level functional maps of the cell. More broadly, we are interested in the role of epistasis in shaping evolutionary processes.