Invasive species are co-introduced with microbiota from their native range and also interact with microbiota found in the novel environment to which they are introduced. Host flexibility toward microbiota, or host promiscuity, is an important trait underlying terrestrial plant invasions. To test whether host promiscuity may be important in macroalgal invasions, we experimentally simulated an invasion in a common garden setting, using the widespread invasive macroalga Agarophyton vermiculophyllum as a model invasive seaweed holobiont. After disturbing the microbiota of individuals from native and non-native populations with antibiotics, we monitored the microbial succession trajectories in the presence of a new source of microbes. Microbial communities were strongly impacted by the treatment and changed compositionally and in terms of diversity but recovered functionally by the end of the experiment in most respects. Beta-diversity in disturbed holobionts strongly decreased, indicating that different populations configure more similar –or more common– microbial communities when exposed to the same conditions. This decline in beta-diversity occurred not only more rapidly, but was also more pronounced in non-native populations, while individuals from native populations retained communities more similar to those observed in the field. This study demonstrates that microbial communities of non-native A. vermiculophyllum are more flexibly adjusted to the environment and suggests that an intraspecific increase in host promiscuity has promoted the invasion process of A. vermiculophyllum. This phenomenon may be important among invasive macroalgal holobionts in general.

入侵物种与其原生范围内的微生物群共同引入，并且还与在它们被引入的新环境中发现的微生物群相互作用。宿主对微生物群的灵活性或宿主滥交是陆生植物入侵的重要特征。为了测试宿主滥交在大型藻类入侵中是否很重要，我们使用广泛的侵入性大型藻类Agarophyton vermiculophyllum通过实验模拟了普通花园环境中的入侵作为一个模型入侵海藻 holobiont。在用抗生素干扰了来自本地和非本地种群的个体的微生物群之后，我们在新的微生物来源存在的情况下监测了微生物的演替轨迹。微生物群落受到处理的强烈影响，并且在组成和多样性方面发生了变化，但在实验结束时在大多数方面都恢复了功能。受干扰的全生物的 β 多样性大幅下降，表明不同种群在相同条件下配置更相似或更常见的微生物群落。β-多样性的这种下降不仅发生得更快，而且在非本地人口中也更为明显，而来自本地人口的个体保留的社区与在实地观察到的更相似。A. vermiculophyllum更灵活地适应环境，并表明宿主混杂的种内增加促进了A. vermiculophyllum的入侵过程。一般而言，这种现象在侵入性大型藻类全生物中可能很重要。