Resource ratio fluctuations drive the evolution of microbial metabolic strategies

Abstract

Microorganisms employ diverse metabolic strategies to cope with environmental variability, yet the evolutionary conditions that favor specialists, hierarchical utilizers, or co-utilizers remain poorly understood. Here, we investigate how fluctuations in resource supply ratios drive the evolution of metabolic strategies. By simulating microbial community assembly in environments with variable resource ratios, we show that diverse metabolic strategies emerge as evolutionary optima in different fluctuation regimes. We find that environments with balanced resource supply select for specialists, whereas imbalanced environments select for generalists. As the magnitude of fluctuations in resource supply ratios progressively increases, generalist strategies smoothly shift from those of hierarchical utilizers to co-utilizers. We identify the duration of temporal niches as the mechanistic driver that selects for reduced lag times over maximal growth rates. These findings demonstrate how the temporal structure of resource availability can spontaneously generate the three distinct metabolic strategies observed in nature.