Privatisation rescues function following loss of cooperation

Area of Science:

• Evolutionary biology
• Microbial ecology
• Social evolution

Background:

• Cooperator-cheat dynamics are fundamental to understanding social evolution.
• Cheat invasion is often equated with population extinction in theoretical models.
• The social dynamics of microbial populations in natural environments require further investigation.

Purpose of the Study:

• To investigate whether cheat invasion inevitably leads to extinction in natural populations.
• To explore the social dynamics of iron metabolism in *Pseudomonas aeruginosa* during cystic fibrosis infections.
• To understand the evolutionary pathways from cooperative to private behaviors.

Main Methods:

• Longitudinal study of *Pseudomonas aeruginosa* social dynamics during cystic fibrosis lung infection.
• Phenotypic assays to assess cooperative and private iron acquisition strategies.
• Whole-genome sequencing to identify genetic underpinnings of behavioral shifts.

Main Results:

• Cooperative iron acquisition was upregulated early in infection, increasing cheat invasion risk.
• A private iron acquisition system was upregulated only after the loss of cooperative iron acquisition.
• The benefit of private system upregulation was contingent on iron availability.

Conclusions:

• Cheat invasion does not necessarily equate to extinction; populations can evolve alternative strategies.
• Social dynamics and past interactions significantly influence the evolution of private traits.
• Understanding microbial social evolution is crucial for predicting population dynamics in host environments.