COS 11-8
Patterns of within and among site diversity of amphibian skin microbiota
Amphibians host a diverse assemblage of microbes on their skin. Different amphibian species are known to harbor unique microbial communities. However, the extent of variation in community composition that may be found within a single species is less understood. We studied the diversity of the skin microbiota of spring peepers (Pseudacris crucifer) at two spatial scales: among individuals at ponds and among nine ponds sampled across the state of Virginia, USA. Sampling took place in the spring of 2012, and included the measurement of two water quality variables (temperature and pH) and an assessment of Batrachochytrium dendrobatidis (a fungal pathogen of amphibians) infection at each pond. Our aim was to elucidate any underlying patterns in the distributions of bacterial OTUs (operational taxonomic units ~species) among sites and to determine the contributions of spatial versus environmental variables to among-pond variation in community composition. Microbial community diversity was assessed by swabbing the skin of the frogs and sequencing the V4 region of the 16S rRNA gene on the Illumina Mi-Seq platform.
Results/Conclusions
We collected data on microbial community composition for a total of 117 spring peepers across nine ponds (7-19 individuals per pond). Microbial communities on the skin of spring peepers were typically dominated by a few abundant OTUs in the phyla Proteobacteria and Actinobacteria, the specific identity of which varied within and among ponds. Additionally, spring peepers harbored a high diversity of rare, less abundant taxa. Within ponds, species richness varied as much as 10 fold among individuals. Among ponds, both species richness (samples pooled for each pond) and the compositional similarity among individuals varied. Distance between ponds ranged from 5-269 km. The cutaneous microbial communities on spring peepers at ponds that were closer to one another tended to be more compositionally similar than at ponds that were further apart. However, we found that variation in community structure among ponds was explained by both environmental and spatial variables.