Coevolutionary arms races between bacteria and bacteriophage.

Area of Science:

• Microbial Ecology
• Evolutionary Biology
• Theoretical Biology

Background:

• Bacteriophage (phage) and bacteria engage in rapid coevolutionary dynamics.
• Phage infect bacteria using surface receptors crucial for bacterial nutrient uptake, creating selective pressure.
• This interaction drives reciprocal adaptations in bacterial receptors and phage tail fibers.

Purpose of the Study:

• To develop a computational and theoretical framework for analyzing bacteriophage- and bacteria- coevolutionary dynamics.
• To investigate the conditions leading to coevolutionary branching and the emergence of distinct microbial quasispecies.
• To explore the ecological context and functional specialization arising from these coevolutionary processes.

Main Methods:

• Utilized adaptive dynamics to create a mathematical model of trait adaptations.
• Incorporated host efficiency in resource uptake and phage resistance, and phage host preference.
• Employed stochastic Monte Carlo simulations in a chemostat environment to validate model predictions.

Main Results:

• Identified conditions for coevolutionary branching and parameters leading to distinct quasispecies.
• Demonstrated that multiple bacteria and phage quasispecies can coexist in a homogeneous environment.
• Showed that phage quasispecies exhibit specialized adsorption to specific bacterial quasispecies, indicating endogenous functional differentiation.

Conclusions:

• The proposed framework accurately models rapid coevolutionary dynamics between bacteriophage and bacteria.
• Coevolution can lead to the emergence of diverse microbial communities with specialized interactions.
• The study provides a basis for experimental validation using model organisms like Escherichia coli and lambda phage.