Clonality and non-linearity drive facultative-cooperation allele diversity

Area of Science:

• Evolutionary Biology
• Microbial Ecology
• Population Genetics

Background:

• Kin discrimination, the differential treatment of kin versus non-kin, is crucial in microbial interactions.
• Facultative cooperation, where investment increases with kin abundance, is a key kin-discriminative behavior.
• The evolutionary maintenance of diversity in kin-discrimination loci remains poorly understood, especially concerning population structure.

Purpose of the Study:

• To investigate the impact of population structure on kin-discriminative interactions.
• To explain the maintenance of facultative cooperation allele diversity.
• To link microbial social behavior to population dynamics.

Main Methods:

• Mathematical modeling of kin-discriminative interactions.
• Agent-based simulations of microbial colony expansion.
• Analysis of experimental data on quorum-sensing in Bacillus subtilis.

Main Results:

• Low relatedness in non-clonal groups is necessary for maintaining facultative cooperation allele diversity.
• High clonality is required to stabilize this diversity against exploitation by non-cooperators.
• Simulations show that expanding microbial colonies naturally exhibit population structures conducive to kin discrimination.
• Experimental data confirms the relevance of frequency-dependent interactions in Bacillus subtilis.

Conclusions:

• Population structure uniquely influences kin-discriminative interactions and facultative cooperation.
• The interplay between clonality, exploitation, and kin discrimination is critical for the evolution of cooperation.
• This study provides a framework for understanding the diversity of cooperation strategies in microbial populations.