LAUSR

Abstract In orchids, most of the root-associated fungal endophytes remain undescribed as well as the drivers that affect their interactions with the plants. We characterized root-associated fungal endophytes of co-existing orchids across sites in two areas of montane rainforest in the southern Ecuadorian Andes. We amplified the nrDNA ITS2 region of 130 orchid individuals with Illumina MiSeq technology and tested whether changes in the structure of fungal communities are associated with hosts' phylogeny or the sites where the orchids grow. We identified 3492 OTUs corresponding to the Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Zygomycota phyla. Fungal communities associated with orchids at the lower geographic areas (between 2050 and 2800 m a.s.l.) showed that host evolution and sites are drivers that could shape distinct fungal communities, while at the highest geographic areas (between 3000 and 3500 m a.s.l.), no distinct fungal communities were found neither between co-existing orchid species nor between sites. These results suggested that among orchid species, abiotic and biotic factors do not influence the composition of fungal communities in the same way.