Pitt-CMU Colloquium: Andrew Mugler (Pitt)

Title: Universality in microbial ecology Abstract: A longstanding puzzle in microbial ecology is "the paradox of the plankton": how can a large number of species coexist on a small number of resources without the fastest-growing species outcompeting the rest? Modern experiments addressing this question reveal strong fluctuations and universal behavior in microbial abundances, suggesting that this puzzle can be addressed using tools from statistical physics. I will describe several examples of this approach that reveal different mechanisms of resolving the paradox. I particular, I will describe work with our experimental collaborators, whose data show that thousands of bacterial populations can coexist in a mouse tissue. Our minimal model explains the populations' universal abundance statistics and suggests that they avoid extinction by forming spatial niches. This field represents a frontier for statistical physics and in turn demonstrates that physics approaches can yield fundamental insights for ecology.