Priority effects can persist across floral generations in nectar microbial metacommunities

The order of species arrival can influence how species interact with one another and, consequently, which species may coexist in local communities. This phenomenon, called priority effects, has been observed in various types of communities, but it remains unclear whether priority effects persist over the long term spanning multiple generations of local communities in metacommunities. Focusing on bacteria and yeasts that colonize floral nectar of the sticky monkey flower, Mimulus aurantiacus, via hummingbirds and other flower-visiting animals, we experimentally manipulated initial microbial dominance on plants (regarded as metacommunities) to examine whether its effects persisted across multiple generations of flowers (regarded as local microbial habitats). The experimental introduction of Neokomagataea (= Gluconobacter) bacteria and Metschnikowia yeasts into wild flowers showed that the effects of initial dominance were observable across multiple floral generations. Three weeks after introduction, corresponding approximately to three floral generations, Neokomagataea introduction led to exclusion of yeasts, whereas Metschnikowia introduction did not result in the exclusion of Neokomagataea. Our results suggest that, even when local habitats are ephemeral, priority effects may influence multiple generations of local communities within metacommunities.