Data from: Defector clustering is linked to cooperation in a pathogenic bacterium

Spatial clustering is thought to favour the evolution of cooperation because it puts cooperators in a position to help each other. However, clustering also increases competition. The fate of cooperation may depend on how much cooperators cluster relative to defectors, but these clustering differences have not been the focus of previous models and experiments. By competing siderophore-producing cooperator and defector strains of the opportunistic pathogen Pseudomonas aeruginosa in experimental microhabitats, we found that at the spatial scale of individual interactions, cooperator clustering lowers cooperation, but defector clustering favours cooperation. A theoretical model and individual-based simulations show these counterintuitive effects can arise when competition and cooperation occur at a single resource-determined scale, with population dynamics crucially allowing cooperators and defectors to cluster differently. The results suggest that cooperation relies on the regulation of sufficient defector clustering relative to cooperator clustering, which may be important in bacteria, social amoeba, and cancer inhibition.空间聚类（spatial clustering）被认为有利于合作的演化，因其可使合作策略者（cooperator）处于相互帮扶的有利位置。然而，聚类同时也会加剧竞争。合作的存续与否或许取决于合作策略者相对于背叛策略者（defector）的聚类程度，但此前的模型与实验并未关注这类聚类差异。我们在实验微生境中培养机会致病菌铜绿假单胞菌（Pseudomonas aeruginosa）的产铁载体合作策略者菌株与背叛策略者菌株并开展竞争实验，结果发现：在个体交互的空间尺度下，合作策略者的聚类会削弱合作，而背叛策略者的聚类则会促进合作。理论模型与基于个体的模拟（individual-based simulations）表明，当竞争与合作发生在单一资源决定的尺度下，且种群动态（population dynamics）恰好允许合作策略者与背叛策略者产生差异化聚类时，便会出现这类反直觉的效应。研究结果显示，合作的维持依赖于背叛策略者相对于合作策略者的适度聚类调控，这一结论在细菌、社会性阿米巴虫（social amoeba）以及癌症抑制领域均具有重要参考价值。