Metschnikowia reukaufii strain:MR1 Raw sequence reads. Metschnikowia reukaufii strain:MR1

Priority effects, where arrival order and initial relative abundance modulate local species interactions, can exert taxonomic, functional, and evolutionary influences on ecological communities by driving them to alternative states. It remains unclear if these wide-ranging consequences of priority effects can be explained systematically by a common underlying factor. Here, we identify such a factor in an empirical system. In a series of field and laboratory studies, we focus on the pH of floral nectar affecting nectar-colonizing microbes and their interactions with plants and pollinators.In laboratory experiments, Acinetobacter nectaris, the bacterium most commonly found in nectar, exerted a strongly negative priority effect against Metschnikowia reukaufii, the most common nectar-specialist yeast, by reducing nectar pH. This priority effect likely explains the mutually exclusive pattern of dominance found in the field survey. Furthermore, experimental evolution simulating hummingbird-assisted dispersal between flowers over a two-month period revealed that M. reukaufii could evolve rapidly to improve resistance against the priority effect if constantly exposed to A. nectaris-induced pH reduction.This dataset includes raw sequencing reads from the resequenced evolved strains of M. reukaufii as part of this laboratory evolution experiment.Taken together, these results show that it is possible to identify an overarching factor that simultaneously governs a diversity of eco-evolutionary consequences of priority effects.