Holobionts are defined as a host and its microbiota, however, only a fraction of the bacteria are inherited vertically and thus coevolve with the host. The “it’s the song, not the singer” theory proposes that functional traits, instead of taxonomical microbiota composition, could be preserved across generations if interspecies interaction patterns perpetuate themselves. We tested conservation of functional composition across generations using zooplankton, mosquito, and plant datasets. Then, we tested if there is a change of functional microbiota composition over time within a generation in human datasets. Finally, we simulated microbiota communities to investigate if (pairwise) interactions can lead to multiple stable community compositions. Our results suggest that the vertically transmitted microbiota starts a predictable change of functions performed by the microbiota over time, whose robustness depends on the arrival of diverse migrants. This succession culminates in a stable functional composition state. The results suggest that the host-microbiota interaction and higher order interactions in general have an important contribution to the robustness of the final community. If the proposed mechanism proves to be valid for a diverse array of host species, this would support the concept of holobionts being used as units of selection, including animal breeding, suggesting this has a wider applicability.

全生物被定义为宿主及其微生物群，然而，只有一小部分细菌是垂直遗传的，因此与宿主共同进化。“这是歌曲，而不是歌手”理论提出，如果种间相互作用模式得以延续，功能特征（而不是分类微生物群组成）可以在几代人中得以保留。我们使用浮游动物、蚊子和植物数据集测试了各代功能组成的保守性。然后，我们测试了人类数据集中一代人内功能微生物群组成是否随时间发生变化。最后，我们模拟了微生物群落，以研究（成对）相互作用是否可以导致多种稳定的群落组成。我们的结果表明，随着时间的推移，垂直传播的微生物群开始使微生物群所执行的功能发生可预测的变化，其稳健性取决于不同迁徙者的到来。这种连续性最终形成稳定的功能组合状态。结果表明，宿主-微生物群相互作用和高阶相互作用通常对最终群落的稳健性具有重要贡献。如果所提出的机制被证明对多种宿主物种有效，这将支持全生物作为选择单位的概念，包括动物育种，表明其具有更广泛的适用性。