The ecology and evolution of small, synthetic bacterial communities.

Short and long-term dynamics in a small bacterial community If you take a gram of soil or a swab of dental plaque and identify the species living within it, you will likely find tens to hundreds of microbial species. But these samples provide just a glimpse of an ecosystem that may be changing constantly, as species interact, adapt to each other and to their environment. If we are to understand how these ecosystems work, we need to follow these dynamics over time to understand how they play out. While this is very challenging in a natural system, we have developed a four-species bacterial community where we can do this relatively easily. I will start by presenting our first findings: that interactions between species are not static, but depend on the environment. A more harsh environment increases positive interactions between species. We then ask whether these positive interactions promote stable coexistence between species, and how they may evolve and adapt to one another.