Informatics and statistics for: Stable coexistence or competitive exclusion? Fern endophytes demonstrate rapid turnover favoring a dominant fungus

Fungal endophytes are critical members of the plant microbiome, but their community dynamics throughout an entire growing season are underexplored. Additionally, most fungal endophyte research has centered on seed-reproducing hosts, while spore-reproducing plants spend a significant proportion of their lifecycle in a haploid state and may filter vertically-transmitted fungi. In order to examine annual fungal endophyte community dynamics in a spore-reproducing host, we examined endophytes in a single population of ferns, Polystichum munitum, in the Pacific Northwest. Through culture-independent sequencing, we characterized the community assembly and temporal turnover of foliar endophytes throughout a growing season. From these results, we selected endophytes with outsized representations in sequence data and performed in vitro competition assays. Finally, we inoculated sterile fern gametophytes with dominant fungi observed in the field and determined their effects on host performance. Se...