A microbial modified prisoner's dilemma game: how frequency-dependent selection can lead to random phase variation

Area of Science:

• Microbiology
• Evolutionary Biology
• Theoretical Biology

Background:

• Random phase variation (RPV) is a gene expression strategy where cells alternate between 'on' and 'off' states.
• While common in bacteria, the specific advantages of RPV under different selective pressures remain unclear.

Purpose of the Study:

• To investigate the conditions under which RPV provides a survival advantage.
• To analyze RPV's role in frequency-dependent environments and its evolutionary stability.

Main Methods:

• Theoretical modeling of RPV dynamics in fluctuating and frequency-dependent environments.
• Analysis of RPV's impact on population heterogeneity and growth rates.
• Comparison of RPV strategies with population polymorphism and game theory models.

Main Results:

• Slow RPV rates confer survival benefits in frequency-dependent environments by generating population heterogeneity.
• Optimal RPV rates can increase population growth but are evolutionarily unstable.
• Individual cells have an incentive to deviate from optimal RPV rates, mirroring a modified Prisoner's Dilemma.

Conclusions:

• RPV offers a survival advantage in specific environmental contexts, particularly frequency-dependent ones.
• The evolutionary instability of optimal RPV highlights a conflict between individual incentives and population fitness.
• RPV dynamics can be understood through the lens of game theory, with optimal rates representing a cooperative strategy vulnerable to defection.