Condensed Matter/Materials & Biological Physics Seminar with Gabriel Birzu on Temporal scales of microbial evolution in nature

Many nonequilibrium phenomena, such as turbulence, climate dynamics, or evolution, occur across a wide range of spatial andtemporal scales. But in evolution, most of our quantitative understanding comes from studying well-mixed populations over time scales of at most a few years. Here, we show how fine-scale patterns of genetic diversity can reveal surprising insights into the evolutionary history of a cyanobacterial population from the Yellowstone National Park. By combining information from geological records with genetic sequencing analysis, we find that on time scales of 104 years barriers between species are gradually eroded. This very slow hybridization process occurs over an area of ~3500 km2, in which the population is effectively well-mixed. These results suggest that effective parameters describing microbial evolution on long time scales may be very different from the parameters measured in experiments, which poses exciting new challenges for theory. Finally, I will discuss ongoing work tackling this problem using simple evolutionary models.