title: Assessing host extinction risk following exposure to Batrachochytrium dendrobatidis.
abstract: Wildlife diseases are increasingly recognized as a major threat to biodiversity. Chytridiomycosis is an emerging infectious disease of amphibians caused by the fungus Batrachochytrium dendrobatidis (Bd). Using a mathematical model and simulations, we study its effects on a generic riparian host population with a tadpole and adult life stage. An analytical expression for the basic reproduction quotient, Qo, of the pathogen is derived. By sampling the entire relevant parameter space, we perform a statistical assessment of the importance of all considered parameters in determining the risk of host extinction, upon exposure to Bd. We find that Qo not only gives a condition for the initial invasion of the fungus, but is in fact the best predictor for host extinction. We also show that the role of tadpoles, which in some species tolerate infections, is ambivalent. While tolerant tadpoles may provide a reservoir for the fungus, thus facilitating its persistence or even amplifying its outbreaks, they can also act as a rescue buffer for a stressed host population. Our results have important implications for amphibian conservation efforts.
authors.affiliation: Institute of Applied Mathematics, University of British Columbia, , 121-1984 Mathematics Road, Vancouver, British Columbia, Canada , V6T 1Z2, Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, , Apartado 21827, Caracas 1020-A, Venezuela, Department of Zoology, University of British Columbia, , 6270 University Boulevard, Vancouver, British Columbia, Canada , V6T 1Z4, Department of Mathematics, University of British Columbia, , 6270 University Boulevard, Vancouver, British Columbia, Canada , V6T 1Z4.
authors.forename: Stilianos
authors.initials: S
authors.lastname: Louca
authors.forename: Margarita
authors.initials: M
authors.lastname: Lampo
authors.forename: Michael
authors.initials: M
authors.lastname: Doebeli
mesh_terms: D000818:Animals; D001001:Anura / Q000254:growth & development / Q000502:physiology; D008411:Chytridiomycota / Q000502:physiology*; D021821:Communicable Diseases, Emerging / Q000453:epidemiology* / Q000382:microbiology*; D053476:Extinction, Biological; D007814:Larva / Q000502:physiology; D008954:Models, Biological; D009181:Mycoses / Q000453:epidemiology* / Q000382:microbiology*; D013997:Time Factors
keywords: basic reproduction quotient; chytridiomycosis; epizootic; extinction; invasion