Synthetic ecology: A model system for cooperation

Synthetic biology offers the promise of a better understanding of biological systems through constructing them. Unlike naturally occurring biological systems, which are generally complicated by multiple variables and difficult to isolate components, synthetic systems can be simplified to allow for experiments that would be too difficult to interpret if done in their full natural context. Up to now, synthetic biologists have primarily focused on gene circuits, such as oscillators and switches (reviewed in ref. 1). By building synthetic genetic circuits, researchers in the field have been able to learn more about the rules of gene expression and regulation, including fundamental issues regarding noise, timing, and signal fidelity, for example. In this issue of PNAS, Shou et al. (2) demonstrate an example of a new direction for synthetic biology, what might be called synthetic ecology. Rather than using gene modules as building blocks, they mix cell populations to construct a synthetic simple obligatory cooperative ecology and use it as the basis of a model for the robustness and boundary parameters of such systems.

Previous experimental and theoretical studies of cooperative or mutualistic ecologies have raised questions about the origin and stability of such systems (reviewed in ref. 3). Cooperation, by which one population or individual contributes to the survival of another at cost to itself, poses some problems. How could such a seemingly delicately balanced and evolutionarily problematic system (i) come about at all, (ii) persist through perturbations such as bottlenecks of one or both populations, and (iii …

*E-mail: maitreya{at}princeton.edu