Impact of Chytrid Fungus Pathogen on Skin Microbiome of Columbia Spotted Frogs in Northern Idaho

Faculty Mentor

Dr. Jenifer Walke


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Document Type

Oral Presentation

Publication Date

Spring 5-18-2020




Chytridiomycosis, an emerging infectious disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), is associated with an estimated 501 population declines and 90 extinctions of amphibian species worldwide, the greatest documented loss of biodiversity attributed to a disease. Research on the amphibian skin microbiome may provide solutions to conservation of amphibian species by bettering our understanding of 1) Bd’s effect on the skin’s microbial community composition and 2) the effects of microbial community composition in protection against Bd. Our goal was to investigate differences in microbiome composition between infected and uninfected frogs. DNA samples from skins of 399 Columbia spotted frogs (Rana luteiventris) were obtained by the Idaho Department of Fish and Game in 2013-2014. Frogs were sampled from a total of 153 wetlands in northern Idaho, with Bd being detected on frogs in 80% (123) of the sampled wetlands. Of the 399 spotted frogs tested for Bd presence, 65% (261 frogs) tested positive. The average infection intensity was low, with zoospore equivalents ranging from 0 to 98.8 (mean = 0.93). The skin microbiomes of 92 frogs (47 infected and 45 uninfected) were characterized using amplicon barcoded sequencing of the V4-V5 region of the 16S rRNA gene. Infected and uninfected frogs had distinct microbiomes (p = .024, pseudo-F = 2.07, PERMANOVA, weighted UniFrac). A member of the order Burkholderiales, known to dominate the microbiome of highly infected frogs, increased in relative abundance in infected frogs. Pseudomonas spp., a known inhibitor of Bd, had greater relative abundance in uninfected frogs, potentially improving defenses against the disease.

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