Remarkably Complex Microbial Community Composition in Bromeliad Tank Waters Revealed by eDNA Metabarcoding

To investigate patterns of biotic community composition at different spatial scales and biological contexts, we used environmental DNA metabarcoding to characterize eukaryotic and prokaryotic assemblages present in the phytotelmata of three bromeliad species (Aechmea gamosepala, Vriesea friburgensis, and Vriesea platynema) at a single Atlantic Forest site in southern Brazil. We sampled multiple individuals per species and multiple tanks from each individual, totalizing 30 samples. We observed very high levels of diversity in these communities, and remarkable variation across individuals and even among tanks from the same individual. The alpha diversity was higher for prokaryotes than eukaryotes, especially for A. gamosepala and V. platynema samples. Some biotic components appeared to be species-specific, while most of the biota was shared among species, but varied substantially in frequency among samples. Interestingly, V. friburgensis communities (which were sampled at nearby locations) tended to be more heterogeneous across samples, for both eukaryotes and prokaryotes. The opposite was true for V. platynema, whose samples were more broadly spaced but whose communities were more similar to each other. Our results indicate that additional attention should be devoted to within-individual heterogeneity when assessing bromeliad phytotelmata biodiversity, and highlight the complexity of the biotic assemblages gathered in these unique habitats.