Thomas Scheuerl, Timothy Barraclough, Damian Rivett

When bacteria evolve new traits, this can be either to our benefit or harm. Trying to steer and control evolution in desirable directions is a major, but daunting aspiration of recent research. In natural systems and complex communities, however, it is repeatedly observed that trait evolution regularly deviates from predicted avenues suggested by in vitro experimentation on monocultures. This pinpoints the effects of species interactions within microbial networks, which opens the door to use them to direct evolution. Unfortunately, this is not trivial; the impacts of ecological interactions between species within communities on evolutionary trajectories are not yet fully understood. Beside the introduced complexity caused by multiple species interactions, the nature of affected niches should also be important. When evolution of environmental β-niche traits (e.g. pH adaptation or antibiotic treatment resistance) is of concern, biotic interactions may have little direct impact. However, evolution of resource-based α-niche traits (e.g. broadened resource consumption) within competitive communities commonly is and could modify evolution of β-niches indirectly. Thus, co-evolving communities may display so far unpreceded opportunities to deflect trait evolution that cannot be achieved in other ways. Intelligent designed studies, building on ecological and evolutionary principles, will be needed to move this field forward.