Amphibian Fungal Disease Dynamics Chytridiomycosis fungus dynamics in wildlife Gabriela Rios-Sotelo Vance Vredenburg Lab San Francisco State University

Amphibian diversity Emerging disease

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 Global amphibian declines Emerging 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

Batrachocytrium dendrobatidis(Bd) lifecycle

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, susceptibilty and other factors? Chytrid Dynamics

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  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 K Upton

Bd in Japan  1 st 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 Andrias japonicus 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 Emerging disease in Asia