Coral-associated bacteria demonstrate phylosymbiosis and cophylogeny

Scleractinian corals microbial symbionts influence host health, yet how these coral microbiomes assembled over evolution is not well understood. We survey bacterial and archaeal communities in phylogenetically diverse Australian corals representing more than 425 million years of diversification. We show that corals exhibit anatomical compartmentalization of the microbiome such that the coral surface mucus layer, tissue, and skeleton microbiomes show distinct modern microbial ecology and evolutionary assembly. In corals, these compartments differ greatly in microbial community composition, richness, and response to host vs. environmental drivers. We also find evidence of coral-microbe phylosymbiosis, in which coral microbiome composition and richness reflects coral phylogeny. Surprisingly, the coral skeleton represents the most biodiverse coral microbiome, and also shows the strongest evidence of phylosymbiosis. Together these results trace microbial symbiosis across anatomy during the evolution of a basal animal lineage.

石珊瑚目珊瑚（Scleractinian corals）的微生物共生体可影响宿主健康，但这类珊瑚微生物组在演化过程中的组装机制目前仍未得到充分阐释。本研究对系统发育多样的澳大利亚珊瑚的细菌与古菌群落进行了系统性调研，所涉珊瑚类群的演化分化历史已超过4.25亿年。研究结果表明，珊瑚微生物组存在解剖学分区特征：珊瑚表面黏液层、组织与骨骼的微生物组分别具备独特的现代微生物生态学属性与演化组装模式。在珊瑚体内，不同解剖分区的微生物群落组成、物种丰富度以及对宿主与环境驱动因子的响应均存在显著差异。此外，本研究还发现了珊瑚-微生物系统发育共生（phylosymbiosis）的证据：珊瑚微生物组的组成与物种丰富度能够反映珊瑚的系统发育关系。令人意外的是，珊瑚骨骼是所有珊瑚微生物组中物种多样性最高的分区，同时也展现出最强的系统发育共生信号。综上，本研究追踪了基底动物类群演化过程中跨解剖分区的微生物共生关系演变轨迹。