Expanding the Pulse-Reserve Paradigm to Microorganisms on the Basis of Differential Reserve Management Strategies

The pulse-reserve paradigm (PRP) is central in dryland ecology, although microorganismal traits were not explicitly considered in its inception. We asked if the PRP could be reframed to encompass organisms both large and small. We used a synthetic review of recent advances in arid land microbial ecology combined with a mathematically explicit theoretical model. Preserving the PRPs core of adaptations by reserve building, the model considers differential organismal strategies to manage these reserves. It proposes a gradient of organisms according to their reserve strategies, from nimble responders (NIRs) to torpid responders (TORs). It predicts how organismal fitness depends on pulse regimes and reserve strategies, partially explaining organismal diversification and distributions. After accounting for scaling phenomena and redefining the microscale meaning of aridity, the evidence shows that the PRP is applicable to microbes. This modified PRP represents an inclusive theoretical framework working across life-forms, although direct testing is still needed.