Colonies grown from a single clone on indicator medium. Different morphologies indicates different heritable regulatory responses.

Colonies grown from a single clone on indicator medium. Different morphologies indicates different heritable regulatory responses.

Networks of regulatory interactions determine how organisms express genes and respond to their environment. They are the software controlling the production of biological hardware. Changes in the network of regulatory interactions underlie phenomena as diverse as cancer and bacterial virulence. Regulatory interactions are also short-lived and environment specific, so can be difficult to study systematically. In particular, we know almost nothing about the potential of regulatory networks to evolve in response to environmental challenges. What is known, is that the outcome of these changes play a major role in organismal evolution. 

We are interested in understanding how organisms can rewire regulatory networks to map new environmental signals to an appropriate physiological response. By focusing on a model network–the lactose utilization module of the bacterium Escherichia coli – we can address concrete questions. For example: how does the lactose regulatory module change in response to selection in novel environments? What are the ecological and evolutionary consequences of these changes? What molecular features of the regulatory network are most important in determining the potential of the  module to evolve?

To answer these questions we are applying genome sequencing, precise genetic manipulation, and molecular- and population-level models to understand the basis and ecological implications of evolved changes in the lactose regulation module.