An introduction to phylosymbiosis

Phylosymbiosis was recently formulated to support a hypothesis-driven framework for the characterization of an emerging trend in host-associated microbiomes. Defining phylosymbiosis as “microbial community relationships that recapitulate the phylogeny of their host”, we review the relevant literature and data in the last decade, emphasizing frequently used methods and regular patterns observed in the analyses. Quantitative support for phylosymbiosis is provided by statistical methods evaluating the distinguishability of microbiomes between hosts, topological congruency between the host phylogeny and microbiome dendrogram, and a positive association between host genetic relationships and microbiome beta diversity. Significant degrees of phylosymbiosis are prevalent in gut and surface microbiomes of plants and animals from terrestrial and aquatic habitats. Consistent with natural selection underpinning phylosymbiosis, microbiome transplant experiments demonstrate reduced host performance and/or fitness upon host-microbiome mismatches. The pervasiveness of phylosymbiosis carries several important implications for analyses of host-microbiome interactions, evolutionary biology, personalized microbiology, and conservation biology. Important future steps will be to apply evolutionary modelling for an increasingly sophisticated understanding of phylosymbiosis and to unravel the host and microbial mechanisms that contribute to the pattern. This review serves as a gateway to experimental, conceptual, and quantitative themes of phylosymbiosis and outlines opportunities ripe for investigations from a diversity of disciplines, scholars, and students.