Assessing the social dilemmas in eco-evolutionary dynamics of cooperation, cheating, and resistance under antibiotic pressure

Antibiotic resistance in microbial communities arises from complex eco-evolutionary interactions among cooperative producers, cheaters, and resistant strains, often shaped by underlying social dilemmas. Traditional approaches frequently assume well-mixed populations, overlooking spatial heterogeneity and the resulting impacts on strategic outcomes. In this study, we develop a novel three-strategy game-theoretic framework that integrates replicator dynamics with lattice-based Monte Carlo simulations to assess social dilemmas through the lens of social efficiency deficit (SED). This framework allows us to quantify the gap between socially optimal and evolutionarily stable outcomes under varying ecological and pharmacological conditions, including antibiotic benefit, cooperation cost, resistance cost, and environmental penalty. Analytical results reveal threshold conditions and equilibrium structures that govern transitions between cooperative persistence, cheater dominance, and resistance fixation. High resistance costs and environmental penalties favor cooperation, while elevated production costs or relaxed ecological constraints promote cheating. Negative resistance costs or low ecological penalties enable resistance dominance, sometimes producing bistable or oscillatory regimes. Heatmap analyses synthesize these patterns, demonstrating that cooperation prevails when ecological penalties are substantial and antibiotic benefits are high, whereas cheating or resistance dominate under opposite conditions. Stochastic Monte Carlo simulations further reveal coexistence zones and smoother transitions absent in deterministic models, highlighting spatial and demographic effects. The SED analysis quantifies the divergence between individual and collective payoffs, showing that strong ecological penalties and moderate cost-benefit ratios reduce social inefficiency, leading the system toward cooperative optimality. Collectively, these findings uncover how ecological feedback and evolutionary incentives jointly govern the persistence, coexistence, and suppression of cooperative and resistant behaviours in microbial populations under antibiotic stress.