Defector clustering is linked to cooperation in a pathogenic bacterium

Area of Science:

• Evolutionary biology
• Microbiology
• Theoretical ecology

Background:

• Spatial clustering is hypothesized to promote cooperation by enabling cooperators to support each other.
• However, clustering can also intensify competition, complicating the evolution of cooperation.
• Previous models have not sufficiently explored differential clustering between cooperators and defectors.

Purpose of the Study:

• To investigate the impact of differential spatial clustering between cooperators and defectors on the evolution of cooperation.
• To determine how clustering influences the balance between cooperation and competition in microbial populations.

Main Methods:

• Experimental competition between siderophore-producing cooperator and defector strains of *Pseudomonas aeruginosa* in microhabitats.
• Development of a theoretical model to analyze the effects of clustering on cooperation.
• Individual-based simulations to explore population dynamics and spatial structures.

Main Results:

• At the micro-scale of individual interactions, cooperator clustering reduced cooperation.
• Conversely, defector clustering was found to favor cooperation.
• Differential clustering dynamics were shown to be crucial, enabled by population dynamics.

Conclusions:

• Cooperation's evolution is contingent on regulating defector clustering relative to cooperator clustering.
• These findings have implications for understanding cooperation in bacteria, social amoebas, and cancer inhibition.
• The spatial scale of interactions and resource competition significantly influences cooperative outcomes.