Loud but Overlooked: Pacific Chorus Frogs as Reservoirs for Disease in Sierra Nevada Alpine Habitats
Author: Kira Miller
Faculty Supervisor: Vance Vredenburg
Department: Biology
Amphibians are declining worldwide, in large part due to chytridiomycosis: a cutaneous amphibian disease caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd). However, susceptibility and resistance to Bd varies among amphibian hosts. In California's Sierra Nevada, endangered mountain yellow-legged frogs (Rana sierrae, Rana muscosa) are highly susceptible to Bd infection. In contrast, the co-occurring Pacific chorus frog (Pseudacris regilla) is less susceptible and likely acts as a Bd reservoir host. Although P. regilla are one of the most abundant and widespread amphibians in western North America, this species and its interactions with Bd are understudied. We investigate and compare Bd infection prevalence and intensity between these two amphibian species in the Sierra Nevada. From July to September 2023, we visited 24 alpine lakes occupied by R. sierrae, P. regilla, or both amphibian hosts. We collected swab samples from frogs at each site and used qPCR to quantify Bd infection. We also use 16s rRNA sequencing data from swabs to characterize skin microbial communities of each anuran host, and relate compositional differences to Bd infection intensity. Research suggests that some properties of the skin microbiome may help amphibian hosts survive Bd. A stronger understanding of Bd infection and the skin microbiome of P. regilla may have implications for recovery planning of disease-susceptible species.