Abstract

Experimental evolution has provided insight into the pattern and process of microbial evolution and allowed causative tests of longstanding evolutionary theories. I will discuss work studying the evolution of bacteria-plasmid and bacteria-phage interactions. These experiments show the importance of species interactions as a driver of evolution, and also the importance of rapid compensatory evolution for horizontal gene transfer. Increasingly, though, it is clear that rapid microbial evolution is relevant beyond the lab and can have important applied consequences. This is especially the case for pathogenic microbes, where evolutionary change contributes to disease progression and treatment failure. I will discuss a longstanding collaboration with medical microbiologists studying evolution of Pseudomonas aeruginosa in cystic fibrosis (CF) lung infections. Our findings demonstrate high levels of evolved diversity in clinically important bacterial traits like toxin production and antibiotic resistance, and moreover that this diversity is very dynamic over time and associated with changes in patient health. Using population genomics we have recently discovered a role for patient-to-patient transmission in generating this diversity. An important next step in understanding the role for rapid pathogen evolution in the clinic is to unravel the complex causes of selection acting in infection.