Abstract
Microorganisms communicate, cooperate, recognize one another, fight, and devour each other to occupy their ecological niche. Bacteria can exchange chemical signals over long distances, distinguish self from non-self, or act through direct contact to eliminate their competitors. They also possess numerous immune systems that protect them against bacteriophages. Remarkably, some of their components share a deep evolutionary origin with mechanisms of the innate immune system in animals. Finally, predator-prey relationships appear to be much more widespread among bacteria than previously thought. Cooperation, competition, infection, and predation thus give rise to true social and trophic networks, whose role in ecosystems remains largely underestimated.
