Event Detail

Event Type: 
Mathematical Biology Seminar
Wednesday, November 3, 2021 - 12:00 to 12:50
Kidd 236

Speaker Info

Integrative Biology, Oregon State University

Cooperation is ubiquitous in nature, and yet challenging to explain evolutionarily through a Darwinian "survival of the fittest" lens. This is because cooperating requires the cooperator to take on an additional burden, reducing their fitness. Many mechanisms to sustain cooperation have been suggested, such as kin selection and reciprocal altruism, however, models for these methods are often phenomenological in nature ignoring important biological processes. Can the growth and behavior of bacteria really be encapsulated by game theoretical models where individual cells randomly bump into each other to play the game? The chemostat is a continuous bacterial culturing device with an inflow of nutrients and an outflow of the mixed culture containing the bacteria and nutrient. The inflow and outflow of nutrient is analogous to nutrient turnover and the outflow of bacteria is demonstrative of the naturally occurring death, emigration, and predation that occurs in larger ecosystems. The relationship between the chemostat and larger ecological systems allows us to utilize it to test some of these fundamental evolutionary questions about cooperation. We have married a mechanistic modeling and empirical approach to explore the evolution of cooperation in the socially cooperative bacteria Pseudomonas aeruginosa, which produces an extracellular metabolic enzyme as a public good. Both the math modeling and lab work has shown the cooperating (enzyme producing) bacteria can sustain their population over time when grown on their own, however, when a social cheater (non-enzyme producing) strain is introduced, a Tragedy of the Commons occurs and the population collapses.