Phage Diving: An Exploration of the Carcharhinid Shark Epidermal Virome.

The epidermal microbiome is a critical element of marine organismal immunity, but the epidermal virome of marine organisms remains largely unexplored. The epidermis of sharks represents a unique viromic ecosystem. Sharks secrete a thin layer of mucus which harbors a diverse microbiome, while their hydrodynamic dermal denticles simultaneously repel environmental microbes. Here, we sampled the virome from the epidermis of three shark species in the family : the genetically and morphologically similar ( = 6) and ( = 10) and the outgroup ( = 15). Virome taxonomy was characterized using shotgun metagenomics and compared with a suite of multivariate analyses. All three sharks retain species-specific but highly similar epidermal viromes dominated by uncharacterized bacteriophages which vary slightly in proportional abundance within and among shark species. Intraspecific variation was lower among than among and Using both the annotated and unannotated reads, we were able to determine that the viromes were more similar to that of than they were to that of , suggesting that behavioral niche may be a more prominent driver of virome than host phylogeny.