Abstract
Increasingly, host-associated microbiota are recognized to mediate pathogen establishment, providing new ecological perspectives on health and disease. Amphibian skin-associated microbiota interact with the fungal pathogen, Batrachochytrium dendrobatidis (Bd), but little is known about microbial turnover during host development and associations with host immune function. We surveyed skin microbiota of Colorado’s endangered boreal toads (Anaxyrus boreas), sampling 181 toads across four life stages (tadpoles, metamorphs, subadults and adults). Our goals were to (1) understand variation in microbial community structure among individuals and sites, (2) characterize shifts in communities during development and (3) examine the prevalence and abundance of known Bd-inhibitory bacteria. We used high-throughput 16S and 18S rRNA gene sequencing (Illumina MiSeq) to characterize bacteria and microeukaryotes, respectively. Life stage had the largest effect on the toad skin microbial community, and site and Bd presence also contributed. Proteobacteria dominated tadpole microbial communities, but were later replaced by Actinobacteria. Microeukaryotes on tadpoles were dominated by the classes Alveolata and Stramenopiles, while fungal groups replaced these groups after metamorphosis. Using a novel database of Bd-inhibitory bacteria, we found fewer Bd-inhibitory bacteria in post-metamorphic stages correlated with increased skin fungi, suggesting that bacteria have a strong role in early developmental stages and reduce skin-associated fungi.
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Acknowledgements
We acknowledge Colorado Parks and Wildlife for assistance in sample collection and Bd prevalence data at sample sites. In particular, Kevin Thompson, Boyd Wright, Jennifer Logan and Paul Jones assisted in sample collection and site access. Alba Diana Vilar provided extraordinary field help. Thanks to Antonio Gonzalez, Sophie Weiss, and Tony Walters for computational assistance, and Laura Wagner Parfrey, for help with filtering 18s data. This project was supported by an NSF grant (DEB: 1146284) to VJM and RK and in part by a grant from the John S. Templeton Foundation to VJM and RK. JGK was supported by an NSF graduate fellowship and received funds from the University of Colorado EBIO departmental summer grants.
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Kueneman, J., Woodhams, D., Van Treuren, W. et al. Inhibitory bacteria reduce fungi on early life stages of endangered Colorado boreal toads (Anaxyrus boreas). ISME J 10, 934–944 (2016). https://doi.org/10.1038/ismej.2015.168
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DOI: https://doi.org/10.1038/ismej.2015.168
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