Mapping the Global Emergence of Batrachochytrium dendrobatidis,the Amphibian Chytrid Fungus |
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| Authors: | Deanna H. Olson David M. Aanensen Kathryn L. Ronnenberg Christopher I. Powell Susan F. Walker Jon Bielby Trenton W. J. Garner George Weaver The Bd Mapping Group Matthew C. Fisher |
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| Affiliation: | 1. Pacific Northwest Research Station, U.S. Forest Service, Corvallis, Oregon, United States of America.; 2. Department of Infectious Disease Epidemiology, Imperial College, London, United Kingdom.; 3. Institute of Zoology, Zoological Society of London, London, United Kingdom.; 4. Department of Statistics, Oregon State University, Corvallis, Oregon, United States of America.; University of California Riverside, United States of America, |
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| Abstract: | The rapid worldwide emergence of the amphibian pathogen Batrachochytrium dendrobatidis (Bd) is having a profound negative impact on biodiversity. However, global research efforts are fragmented and an overarching synthesis of global infection data is lacking. Here, we provide results from a community tool for the compilation of worldwide Bd presence and report on the analyses of data collated over a four-year period. Using this online database, we analysed: 1) spatial and taxonomic patterns of infection, including amphibian families that appear over- and under-infected; 2) relationships between Bd occurrence and declining amphibian species, including associations among Bd occurrence, species richness, and enigmatic population declines; and 3) patterns of environmental correlates with Bd, including climate metrics for all species combined and three families (Hylidae, Bufonidae, Ranidae) separately, at both a global scale and regional (U.S.A.) scale. These associations provide new insights for downscaled hypothesis testing. The pathogen has been detected in 52 of 82 countries in which sampling was reported, and it has been detected in 516 of 1240 (42%) amphibian species. We show that detected Bd infections are related to amphibian biodiversity and locations experiencing rapid enigmatic declines, supporting the hypothesis that greater complexity of amphibian communities increases the likelihood of emergence of infection and transmission of Bd. Using a global model including all sampled species, the odds of Bd detection decreased with increasing temperature range at a site. Further consideration of temperature range, rather than maximum or minimum temperatures, may provide new insights into Bd-host ecology. Whereas caution is necessary when interpreting such a broad global dataset, the use of our pathogen database is helping to inform studies of the epidemiology of Bd, as well as enabling regional, national, and international prioritization of conservation efforts. We provide recommendations for adaptive management to enhance the database utility and relevance. |
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