Synthetic Mutualism and the Intervention Dilemma describes how ecosystems are complex networks of interacting individuals co-evolving with their environment. As such, changes to an interaction can influence the whole ecosystem. However, to predict the outcome of these changes, considerable understanding of processes driving the system is required.
Synthetic biology provides powerful tools to aid this understanding, but these developments also allow us to change specific interactions. Of particular interest is the ecological importance of mutualism, a subset of cooperative interactions. Mutualism occurs when individuals of different species provide a reciprocal fitness benefit.
Available experimental techniques of synthetic biology focused on engineered synthetic mutualistic systems. Components of these systems have defined interactions that can be altered to model naturally occurring relationships. Integrations between experimental systems and theoretical models, each informing the use or development of the other, allow predictions to be made about the nature of complex relationships. The predictions range from stability of microbial communities in extreme environments to the collapse of ecosystems due to dangerous levels of human intervention.

A small fraction of the exploratory power that synthetic biology offers in seeking to understand complex population dynamics.
Engineering and design principles being employed are developing modular systems that can be easily used, reused, and modified. This modularity, in turn, affords a level of control, when using these systems, that can keep pace with theoretical models.
Theoretical models often assume predefined interactions between interacting components that can now be precisely engineered in synthetic communities. The closing gap between experimental and theoretical models allows us to test not just assumptions, but predictions of theoretical models. For example, if theory predicts that specific classes of interactions are necessary to stabilize a community under ecological perturbations, then we can design synthetic communities to test our understanding. This will help us better approximate workings of natural or evolved systems in the laboratory and perhaps eventually in the wild.
Current synthetic mutualistic systems have small numbers of interactors, usually two with additional strains acting in a bystander or cheating capacity. These systems are on the verge of being superseded.
The most exciting developments in these synthetic mutualism systems will be the creation of more complex synthetic networks that will allow a higher degree of complexity to be modelled.
Synthetic biology also brings the promise of incorporating different attributes in microbes. This perhaps includes the ability to digest novel substrates or to withstand radiation and other extreme conditions.
Within earth’s most extreme conditions, we find consortia of microbes. This includes the low oxygenation of ponds covered with algae, extreme drought in the Atacama desert, or even in caves representing Mars-like conditions. Learning from these natural systems, we could benefit from allocating super-traits among diverse taxa rather than building one super-organism.
From an academic perspective, synthetic mutualism may also provide sets of bio-signatures to aid the search for extraterrestrial life. Moreover, from an applied perspective it may be possible to construct cooperating systems that can survive not just extreme environments, but to provide a foothold for terraforming other worlds.