Le Moigne Alizée, Randegger Florian, Gupta Anubhav, Petchey Owen L, Pernthaler Jakob
Limnological Station, Department of Plant and Microbial Biology, University of Zurich, Kilchberg, Switzerland.
Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
Ecology. 2023 Apr;104(4):e4005. doi: 10.1002/ecy.4005. Epub 2023 Mar 5.
Stochasticity is a major cause of compositional β-diversity in communities that develop under similar environmental conditions. Such communities may exhibit functional similarity due to sympatric taxa with equivalent metabolic capacities in the source assemblage. However, the redundancy of individual physiological traits may differ in the original source community, which in turn might lead to more or less pronounced variability of single functions among newly formed communities. We analyzed the degree of stochasticity during the primary assembly of bacterial communities originating from the same source and growing under identical conditions. We tested the links between community composition and functioning in parallel microcosms containing glucose and its dimer cellobiose. Bacteria from prefiltered lake water were diluted in artificial lake water and grown to the stationary phase. The resulting assemblages exhibited high compositional variability of taxa that were rare in the source communities. Simulations showed that the observed richness and incidence-based β-diversity could be reproduced by dispersal limitation, or by low dispersal rates associated with the ecological drift of the colonizers. Further null model analysis supported an important influence of stochasticity, as well as a synergy between dispersal limitation and both, heterogeneous and homogeneous selection. The communities functionally differed and the magnitude of functional variability depended on the substrate: more communities consumed glucose than cellobiose. However, there was no relationship between community structure and growth kinetics or substrate consumption. Thus, both structural and functional variability may be a consequence of stochastic processes during initial colonization in closed microbial communities.
随机性是在相似环境条件下发展的群落中组成性β多样性的主要原因。由于源集合中具有同等代谢能力的同域分类群，这样的群落可能表现出功能相似性。然而，单个生理特征的冗余在原始源群落中可能不同，这反过来可能导致新形成的群落中单个功能或多或少明显的变异性。我们分析了源自同一源并在相同条件下生长的细菌群落初级组装过程中的随机程度。我们测试了包含葡萄糖及其二聚体纤维二糖的平行微观世界中群落组成与功能之间的联系。将预过滤湖水中的细菌在人工湖水中稀释并培养至稳定期。所得组合显示出源群落中罕见的分类群具有高组成变异性。模拟表明，观察到的丰富度和基于发生率的β多样性可以通过扩散限制或与定殖者生态漂变相关的低扩散率来再现。进一步的空模型分析支持了随机性的重要影响，以及扩散限制与异质和同质选择之间的协同作用。群落功能不同，功能变异性的大小取决于底物：消耗葡萄糖的群落比消耗纤维二糖的群落更多。然而，群落结构与生长动力学或底物消耗之间没有关系。因此，结构和功能变异性可能都是封闭微生物群落初始定殖过程中随机过程的结果。
