Kira Miller

San Francisco State University

“Investigating the roles of skin microbiota and reservoir hosts in the disease dynamics of two frog species in the Sierra Nevada”

The emergent fungal pathogen Batrachochytrium dendrobatidis (Bd) causes the amphibian disease chytridiomycosis, yet susceptibility to this disease varies among amphibian hosts. My research investigates how compositional differences in the amphibian skin microbiome (symbiotic bacteria) may contribute to disease susceptibility or resistance between two frog species in the Sierra Nevada.


Chytridiomycosis is a cutaneous amphibian disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), and has resulted in amphibian declines worldwide. However, susceptibility to Bd infection varies between host species. In California’s Sierra Nevada mountains, endangered mountain yellow-legged frogs (Rana muscosa) are highly susceptible to Bd. The co-occurring Pacific chorus frog (Pseudacris regilla), on the other hand, is much less susceptible and has been proposed as a Bd reservoir host. Recent studies of amphibian skin microbiomes indicate that in some amphibian species, symbiotic skin bacteria may facilitate survival against Bd infection by producing antifungal compounds. At sites with different amphibian compositions, I will compare R. muscosa and P. regilla skin microbial communities and Bd infection loads to determine how microbiome composition may influence disease outcomes for these hosts. Investigating the microbiomes of co-occurring hosts can inform conservation and recovery planning for disease-susceptible endangered species.

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