UC Santa Barbara

Foliar fungal endophyte (FFE) assemblages are shaped by evolutionary and ecological processes. However, it remains unresolved how the evolutionary history and phylogenetic relatedness of host plants and endophytes influence the assembly process. Testing for phylosymbiosis by measuring correlation between microbial community dissimilarity and host phylogeny in plant-FFE systems can reveal the extent to which these phylogenetic factors influence FFE assemblage. In this paper, I searched for patterns of phylosymbiosis by testing the relationship between phylogenetic distance separating plant hosts and the phylogenetic dissimilarity of their FFE communities from a phylogenetically diverse set of plants collected from 20 sites across seven latitudinal zones. Phylogenetic dissimilarity between FFE communities was defined by three phylogenetic beta diversity (PBD) metrics: UniFrac, phylogenetic community dissimilarity (PCD), and beta mean nearest taxon distance (bMNTD). Phylosymbiosis was not a prevalent pattern across sites, however, plant and FFE communities of the seven sites that showed the strongest indicators of phylosymbiosis revealed that the detection of phylosymbiosis was sensitive to the presence of rare FFE species and the phylogenetic breadth of hosts being tested. Additionally, in some cases, compositional differences between communities were driving phylogenetic community dissimilarity rather than the phylogenetic relationships between FFE species. Phylosymbiosis was not detected when testing the relationship between phylogenetic distance separating endophytes and the phylogenetic dissimilarity of their host communities using PCD and bMNTD as PBD metrics.