Data from: Experimental demonstration of an Allee effect in microbial populations

Microbial populations can be dispersal limited. However, microorganisms that successfully disperse into physiologically ideal environments are not guaranteed to establish. This observation contradicts the Baas-Becking tenet: ‘Everything is everywhere, but the environment selects’. Allee effects, which manifest in the relationship between initial population density and probability of establishment, could explain this observation. Here, we experimentally demonstrate that small populations of Vibrio fischeri are subject to an intrinsic demographic Allee effect. Populations subjected to predation by the bacterivore Cafeteria roenbergensis display both intrinsic and extrinsic demographic Allee effects. The estimated critical threshold required to escape positive density-dependence is around 5, 20 or 90 cells ml−1 under conditions of high carbon resources, low carbon resources or low carbon resources with predation, respectively. This work builds on the foundations of modern microbial ecology, demonstrating that mechanisms controlling macroorganisms apply to microorganisms, and provides a statistical method to detect Allee effects in data.

微生物种群存在扩散限制现象。然而，即便微生物成功扩散至生理适宜的环境中，也未必能够成功定植。这一观测结果与巴斯-贝克信条（Baas-Becking tenet）——“万物无所不在，唯环境自行选择”——相悖。阿利效应（Allee effects）体现为初始种群密度与定植概率之间的关联，可用于解释该观测现象。本研究通过实验证实，费氏弧菌（Vibrio fischeri）的小型种群存在内在种群统计阿利效应；当种群受到食细菌原生动物罗伦食细菌鞭毛虫（Cafeteria roenbergensis）的捕食作用时，会同时表现出内在与外在种群统计阿利效应。在高碳资源、低碳资源以及低碳资源加捕食的实验条件下，为摆脱正密度依赖所需的估算临界阈值分别约为每毫升5、20或90个细胞。本研究立足于现代微生物生态学的研究基础，证明了调控大型生物的生态学机制同样适用于微生物，并提供了一种可用于检测数据中阿利效应的统计方法。