Seminar by Hong-Yan Shih

Emergence of a Stable Nonequilibrium Bacteria-Phage Collective State  from Scale-dependent Feedback

Hong-Yan Shih (University of Illinois)

A key question in astrobiology is to understand the 
timescale and evolutionary trajectory of the microbial communities 
that influence the development of Earth’s environment and the 
biosphere. In particular, what accounts for the stability, 
co-evolution and diversity of microbial and viral ecosystems? We show 
that predator-prey dynamics can lead to an emergent collective state 
between bacteria and their phage, but only if both are able to utilize 
genes that are horizontally transferred. We apply this model to one of 
the world’s most abundant organisms: the marine cyanobacteria 
Prochlorococcus spp. whose phages carry photosystem II genes that 
benefit both the bacteria and the phage. Our results account for the 
emergence of ecotypes and show that non-equilibrium antagonistic 
interactions between organisms, on scales ranging from genomes to the 
environment, can drive ecosystem stability and diversity.