Fungal communities living within leaves of native Hawaiian dicots are structured by landscape-scale variables as well as by host plants

ABSTRACT AIMA phylogenetically diverse array of fungi live within healthy leaf tissue of dicotyledonous plants. Many studies have examined these endophytes within a single plant species and/or at small spatial scales, but landscape-scale variables that determine their community composition are not well understood, either across geographic space, across climatic conditions, or in the context of host plant phylogeny. Here, we evaluate the contributions of these variables to endophyte community composition using our survey of foliar endophytic fungi in native Hawaiian dicots sampled across the Hawaiian archipelago. LOCATIONHawai?i. METHODSThe Hawaiian archipelago offers a uniquely tractable system to study biogeography of foliar endophytic fungi, because the islands harbor a wide array of climatic conditions, and native plant species are often found across wide elevational and climactic ranges. We used Illumina technology to sequence fungal ITS1 amplicons in order to characterize foliar endophyte communities in the leaves of 896 plants across 5 islands and 80 host plant genera. Using Generalized Dissimilarity Modeling (GDM) we tested the effect of landscape-scale variables on observed differences in foliar endophyte communities. Bipartite network analysis was used to examine the extent to which each island harbored specialized or cosmopolitan foliar endophytes. RESULTSCommunities of foliar endophytic fungi in the Hawaiian archipelago are structured most strongly by evapotranspiration, elevation, vegetation/habitat type, and by the phylogeny of host plants. The five islands we sampled each harbored significantly specialized endophyte communities as well. MAIN CONCLUSIONSFactors that structure foliar endophyte communities at small geographic and narrow host phylogenetic scales are broadly generalizable to the larger scales we studied here, although not universally. Evapotranspiration, a variable with resolution 250 m2, was the most robust predictor of endophyte community dissimilarity in our study, although it had not previously been considered an important determinant of FEF communities.