Nonreciprocity in active microbial populations

Active microbial populations are characterized by numerous interacting components, including active and passive elements. For example, animal groups physically interact with their environment and actively avoid predators, yet it's their social engagements that amplify the complexity of these systems. Intriguingly, the emerging concept of nonreciprocity offers fresh angles to untangle these complexities. In this presentation, I will summarize our recent experimental endeavors to understand nonreciprocity and its biological relevance. We have observed experimentally that nonreciprocal interactions among dense microbial populations, which include active and passive members, lead to traveling waves, arrested phase separation, and chiral edge states. I will also touch upon the potential evolutionary implications of these findings in population biology. Finally, I will illustrate the ubiquity of these responses in diverse microbial groups, from bacterial biofilms to nematodes.