Big Question: How do circadian clocks evolve?

Principal Investigator: Michael Rust, Molecular Genetics and Cell Biology

Funding Type: Seed

Focus Area: Complexity

Big Idea: Biological systems consist of networks of interacting components that have been shaped by evolution. A key feature of these networks is that complex functions emerge from the simpler interactions of the components. A concrete example of emergent function is the circadian clock, a ~24 hour rhythm in gene expression that allows organisms to anticipate daily changes in the environment. None of the molecular components of the clock oscillate in isolation - rhythms emerge only from the full network of interactions. Very little is understood about how evolution can produce complex systems of this kind, where the function of each component depends on its context in a strongly interacting network. Our goal is to experimentally determine evolutionary paths that can alter a system’s dynamics and cause oscillatory behavior to emerge. We are exploiting the experimental power of the simplest known bacterial circadian clock, where a small network of three proteins is responsible for generating rhythms. Understanding the mutational sensitivity of this network and its response to environmental fitness pressures will give us an unprecedented view of how random mutation and selection act to build complex biological systems.