Quality–quantity tradeoffs govern the production of propagules across taxa and can explain variability in life-history traits in higher organisms. A quality–quantity tradeoff was recently discovered in spore forming bacteria, but whether it impacts fitness is unclear. Here we show both theoretically and experimentally that the nutrient supply during spore revival determines the fitness advantage associated with different sporulation behaviors in Bacillus subtilis. By tuning sporulation rates we generate spore-yield and spore-quality strategists that compete with each other in a microscopic life-cycle assay. The quality (yield) strategist is favored when spore revival is triggered by poor (rich) nutrients. We also show that natural isolates from the gut and soil employ different life-cycle strategies that result from genomic variations in the number of rap-phr signaling systems. Taken together, our results suggest that a spore quality–quantity tradeoff contributes to the evolutionary adaptation of sporulating bacteria.

质量与数量之间的权衡决定了整个类群中繁殖体的产量，并可以解释高等生物的生命历史特征的变异性。最近在孢子形成细菌中发现了质量-质量的权衡，但是尚不清楚它是否影响健康。在这里，我们在理论上和实验上都表明，孢子复兴过程中的营养供应决定了枯草芽孢杆菌中不同孢子形成行为相关的适应性优势。。通过调节孢子形成率，我们产生了在微观生命周期分析中相互竞争的孢子产量和孢子质量策略家。当营养不良（丰富）触发孢子复兴时，质量（产量）策略师会受到青睐。我们还表明，来自肠道和土壤的天然分离物采用了不同的生命周期策略，这些策略是由rap-phr信号传导系统数量的基因组变异引起的。综上所述，我们的结果表明，孢子质量与数量的权衡有助于孢子形成细菌的进化适应。