Multicoloured greenbeards, bacteriocin diversity and the rock-paper-scissors game

Area of Science:

• Evolutionary Biology
• Microbial Ecology
• Population Genetics

Background:

• Greenbeard genes enable individuals to recognize and favor kin.
• Bacterial toxins (bacteriocins) demonstrate the greenbeard effect via producer immunity.
• Rock-paper-scissors (RPS) dynamics maintain polymorphisms in bacteriocin-producing bacterial populations.

Purpose of the Study:

• To investigate how multiple bacteriocin types (multiple beard colors) affect strain dynamics.
• To determine the conditions promoting polymorphism and coexistence of multiple toxin types.

Main Methods:

• Analysis of strain dynamics using models of recurrent patch colonization.
• Population growth models incorporating local resource competition and mutation.

Main Results:

• Polymorphism is favored by limited founding lineages, strong competition, and mutations.
• Static or dynamic polymorphism depends on interaction intensity and toxin/immunity costs.
• Multiple toxins can promote RPS dynamics and strain diversity.
• Strain diversity is maintained even with varying toxin efficacy or multi-toxin/immunity.

Conclusions:

• Factors maintaining simple RPS dynamics also promote the coexistence of multiple bacteriocin types.
• This provides an explanation for the extensive bacteriocin diversity observed in natural environments.
• Contrasts are drawn with marker diversity maintenance in genetic kin recognition.