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

Abstract

A 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 beta diversity using a survey of foliar endophytic fungi in native Hawaiian dicots sampled across the Hawaiian archipelago. We used Illumina technology to sequence fungal ITS1 amplicons to characterize foliar endophyte communities across five islands and 80 host plant genera. We found that communities of foliar endophytic fungi showed strong geographic structuring between distances of 7 and 36 km. Endophyte community structure was most strongly associated with host plant phylogeny and evapotranspiration, and was also significantly associated with NDVI, elevation and solar radiation. Additionally, our bipartite network analysis revealed that the five islands we sampled each harboured significantly specialized endophyte communities. These results demonstrate how the interaction of factors at large and small spatial and phylogenetic scales shapes fungal symbiont communities.

Plant–microbe specificity varies as a function of elevation

“…This increased scale may lead to greater effects as well an increased likelihood that both host genetic variation and/or fungal dispersal limitation, in addition to environmental variance, might also contribute to their patterns noted. In fact, in a larger archipelago-wide survey of endophytes associated with >100 host plant species and spanning 2300 m in elevation, we found that numerous environmental factors, principally elevation and plot level evapotranspiration, correlated with endophyte community composition [62].…”

Core arbuscular mycorrhizal fungi are predicted by their high abundance–occupancy relationship while host‐specific taxa are rare and geographically structured

“…This reduced the dimensions of our geographic data and created spatial predictors (‘Geo’ vectors) that could be incorporated into a principal coordinates analysis (PCoA) that also included our categorical variable of habitat type. The first six vectors were used to represent the contribution of geography to community composition and were fit to the matrix using the envfit function (Dray et al ., 2006; Oksanen et al ., 2013; Darcy et al ., 2020).…”

Climate and seasonality drive the richness and composition of tropical fungal endophytes at a landscape scale

“…They typically are transferred horizontally as airborne spores and hyphae, forming communities that are structured at local scales by host phylogeny and traits such as secondary metabolites and leaf phenology 15 , 18 – 20 . At a larger scale, environmental factors such as temperature, precipitation, and vegetation are relevant to endophyte community structure in all biomes surveyed to date 21 – 24 , underscoring the interplay of abiotic and biotic drivers in shaping assemblages of these hyperdiverse and important symbionts.…”