Phase separation and coexistence in spatial coordination games between microbes.

Area of Science:

• Microbial Ecology
• Theoretical Ecology
• Statistical Physics

Background:

• Microbial communities exhibit complex population structures driven by local cell-to-cell interactions.
• Linking microscopic interaction mechanisms to macroscopic coexistence dynamics remains a challenge due to significant variations.
• Understanding how diverse interaction types influence microbial diversity and spatial organization is crucial.

Purpose of the Study:

• To investigate how microbial interactions, spanning antagonism to cooperation, facilitate coexistence through emergent spatial domains.
• To explore the game-theoretic underpinnings of microbial interactions and their impact on population dynamics and structure.
• To identify generic mechanisms governing microbial coexistence in spatially explicit environments.

Main Methods:

• Analysis of a family of stochastic coordination games to model cell-to-cell interactions.
• Investigation of population dynamics governed by a double-well shaped interaction potential.
• Derivation of a partial differential equation (PDE) equivalent to the spatial stochastic game.

Main Results:

• Coordination games exhibit a double-well interaction potential that induces phase separation in spatial settings, promoting coexistence.
• Symmetric coordination games show universal phase separation scaling consistent with 'Model A' coarsening, observed in *Vibrio cholerae*.
• The PDE model confirms the double-well potential and the universality of phase separation in spatial coordination games.

Conclusions:

• Local microbial interactions, modeled via coordination games, can lead to spatial phase separation and facilitate coexistence.
• The emergent spatial domains and phase separation provide a generic mechanism for maintaining microbial diversity.
• This framework links microscopic interaction rules to macroscopic population structures, advancing our understanding of microbial community assembly.