Many studies demonstrate the importance of the commensal microbiomes to animal health and development. However, the initial community assembly process is poorly understood. It is unclear to what extent the hosts select for their commensal microbiota, whether stochastic processes contribute, and how environmental conditions affect the community assembly. We investigated community assembly in Atlantic cod larvae exposed to distinct microbial metacommunities. We aimed at quantifying ecological processes influencing community assembly in cod larvae and at elucidating the complex relationship between the bacteria of the environment and the fish. Selection within the fish was the major determinant for community assembly, but drift resulted in inter-individual variation. The environmental bacteria was highly dissimilar from the fish bacteria. Still, differences in the environmental bacteria strongly influenced the fish bacteria. The most striking difference was an excessive dominance of a single OTU (Arcobacter) for larvae reared in two of the three systems. These larvae were exposed to environments with higher fractions of opportunistic bacteria, and we hypothesise that detrimental host-microbe interactions might have made the fish susceptible for Arcobacter colonisation. Despite strong selection within the host, this points to a possibility to steer the metacommunity towards mutualistic host-microbe interactions and improved fish health and survival.

中文翻译：

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大西洋鳕鱼幼虫（Gadus morhua）的细菌群落大会：生态过程和超群落结构的贡献。

许多研究表明，共生微生物组对动物健康和发育的重要性。但是，最初的社区集会过程知之甚少。尚不清楚宿主在多大程度上选择其共生菌群，随机过程是否起作用以及环境条件如何影响社区集会。我们调查了暴露于不同微生物元群落的大西洋鳕鱼幼虫的群落组装。我们旨在量化影响鳕鱼幼虫群落组装的生态过程，并阐明环境细菌与鱼类之间的复杂关系。在鱼中的选择是决定群落聚集的主要决定因素，但漂移导致个体间的差异。环境细菌与鱼细菌高度不同。仍然，环境细菌的差异极大地影响了鱼类细菌。最明显的区别是单个OTU的支配地位过高（在三个系统中的两个系统中饲养了幼虫的杆状杆菌。这些幼虫暴露于机会细菌比例较高的环境中，并且我们假设有害的宿主-微生物相互作用可能使鱼易患杆状杆菌定植。尽管寄主内有很强的选择能力，但这表明有可能将元群落引向相互之间的寄主-微生物相互作用并改善鱼类的健康和生存。