amphibian fungal disease dynamics chytridiomycosis fungus dynamics in wildlife gabriela rios-sotelo...
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Amphibian Fungal Disease Dynamics
Chytridiomycosis fungus dynamics in wildlife
Gabriela Rios-SoteloVance Vredenburg LabSan 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
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 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