Data from: Low-load pathogen spillover predicts shifts in skin microbiome and survival of a terrestrial-breeding amphibian

Wildlife disease dynamics are strongly influenced by the structure of host
communities and their symbiotic microbiota. Conspicuous amphibian declines
associated with the waterborne fungal pathogen Batrachochytrium
dendrobatidis (Bd) have been observed in aquatic-breeding frogs globally.
However, less attention has been given to cryptic terrestrial-breeding
amphibians that have also been declining in tropical regions. By
experimentally manipulating multiple tropical amphibian assemblages
harboring natural microbial communities, we tested whether Bd spillover
from naturally infected aquatic-breeding frogs could lead to Bd
amplification and mortality in our focal terrestrial-breeding host: the
pumpkin toadlet Brachycephalus pitanga. We also tested whether the
strength of spillover could vary depending on skin bacterial transmission
within host assemblages. Terrestrial-breeding toadlets acquired lethal
spillover infections from neighboring aquatic hosts and experienced
dramatic but generally non-protective shifts in skin bacterial composition
primarily attributable to their Bd infections. In contrast,
aquatic-breeding amphibians maintained mild Bd infections and higher
survival, with shifts in bacterial microbiomes that were unrelated to Bd
infections. Our results indicate that Bd spillover from even mildly
infected aquatic-breeding hosts may lead to dysbiosis and mortality in
terrestrial-breeding species, underscoring the need to further investigate
recent population declines of terrestrial-breeding amphibians in the
tropics.