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Amphibian Fungal Disease Dynamics. Chytridiomycosis fungus dynamics in wildlife Gabriela Rios-Sotelo Vance Vredenburg Lab San Francisco State University. Emerging disease. Amphibian diversity. Emerging disease. Global amphibian declines. Number 1 most threatened vertebrate
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Amphibian Fungal Disease Dynamics Chytridiomycosisfungus dynamics in wildlife Gabriela Rios-Sotelo Vance Vredenburg Lab San Francisco State University
Emerging disease Amphibian diversity
Emerging disease Global amphibian declines • Number 1 most threatened vertebrate • 1/3 (32%) of amphibians are threatened species • May be on the brink of a sixth mass extinction • Many reasons for declines • Recently… • INFECTIOUS DISEASE
Chytridiomycosis (chytrid) • Largest disease-caused loss of species in history • 200 species already driven to extinction • Fungal pathogen specific to amphibians • Transmitted by aquatic zoospores • Infects keratin layers of amphibian skin • Thickened skin leading to blocked osmotic regulation and electrolyte transport Skerratt et al 2007; Voyles et al 2009
Chytrid Dynamics Many questions… • Where did this disease originate? How did amphibians in this area come to live robustly with this fungus? Can we use this knowledge to efficiently protect other species worldwide? • How can we control further disease spread? • How do some species survive with infection while others do not? • How does this particular microbe interact as a skin disease? Does it compete for food and space with other skin microbes? Does this have to do with why some species are more susceptible than others? • How does Bd’s assn. with it’s abiotic environment influence it’s dispersal, susceptibiltyand other factors?
Emerging disease in Asia Worldwide distribution ? Fisher et al 2009 • Bd has been well documented all over the world except Asia
Emerging disease in Asia Bd in Asia • Most unique and diverse areas in the world for amphibian fauna • Recent papers in China, Japan and South Korea show low infection rates and no signs of mass amphibian declines
Emerging disease in Asia Disease Dymanics K Upton • Two hypothesis for Bd emergence • Novel pathogen hypothesis (NPH) • Emerging endemic hypothesis (EEH) EEH pattern would show constant infection prevalence levels demonstrating coevolution in area of origin Berger et al 1998; Rashowicz et al 2005; Pounds et al 2006
Emerging disease in Asia Bd in Japan • 1st distribution of Bd in Japan • Low infection rates • Many haplotypes • Vector mediated spread
Emerging disease in Asia • AS well as the oldest museum specimen record documented with Bd • 1902 Andriasjaponicus K Sweet 2008
Emerging disease in Asia Using museum specimens and PCR to test for Bd • New method developed From Dr. Alex Hyatt’s PCR detection method adapted by Tina Cheng allows Bd detection in preserved museum specimens
Emerging disease in Asia Bd disease Map of Japan