Collaborative Research (RAPID): Testing Intervention Strategies to Change the Outcome of Disease-caused Mass-mortality Events in a Declining Amphibian

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New diseases are emerging at an increasing rate, and in numerous cases are having devastating effects on wildlife species. The amphibian chytrid fungus (Batrachochytrium dendrobatidis; Bd) causes the disease chytridiomycosis that since its emergence has resulted in the extinction or serious decline of hundreds of amphibian species worldwide. In California?s Sierra Nevada, chytridiomycosis has caused the near-extinction of the once-common mountain yellow-legged frog. During summer 2012, the largest remaining mountain yellow-legged frog population will suffer a die-off event caused by the recent arrival of Bd in the area. In mountain yellow-legged frog populations the arrival of Bd in a previously uninfected population typically results in frog population extinction, and the goal of the proposed study is to change the outcome to long-term frog population persistence. This disease intervention will take the form of a field experiment implemented during the Bd-caused frog die-off. In this experiment the effectiveness of two treatments, (1) an antifungal drug, and (2) the augmentation of antifungal bacteria that occur naturally on frog skin, will be assessed at the scale of an entire frog population. This experiment will also provide an opportunity to describe the mechanisms underlying treatment effectiveness, including the role of the frog immune system, the microbial community present on the skin of frogs, and rapid evolution in frogs. Based on results from previous laboratory and small-scale field trials it is expected that antifungal drug and bacterial augmentation treatments will increase frog survival relative to frogs that are left untreated. Results from the proposed study will have important implications for conservation efforts aimed at wildlife species worldwide that are threatened by emerging diseases (e.g., amphibians, bats, apes). The study will also provide training opportunities for undergraduate and graduate students, with every effort made to include those from underrepresented groups to the maximum extent possible.