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Unformatted text preview: 2006 Nature Publishing Group Widespread amphibian extinctions from epidemic disease driven by global warming J. Alan Pounds 1 , Martn R. Bustamante 2 , Luis A. Coloma 2 , Jamie A. Consuegra 3 , Michael P. L. Fogden 1 , Pru N. Foster 4 , Enrique La Marca 5 , Karen L. Masters 6 , Andre s Merino-Viteri 2 , Robert Puschendorf 7 , Santiago R. Ron 2,8 , G. Arturo Sa nchez-Azofeifa 9 , Christopher J. Still 10 & Bruce E. Young 11 As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog ( Atelopus sp.) vanished along with the golden toad ( Bufo periglenes ). An estimated 67% of the 110 or so species of Atelopus , which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus ( Batrachochytrium dendrobatidis ) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with very high confidence ( . 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium , thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable. Humans are altering the Earths climate 14 and thus the workings of living systems 58 , including pathogens and their hosts 911 . Among the predicted outcomes is the extinction of many species 10,12 , but detecting such an effect is difficult against a backdrop of other changes, especially habitat destruction. One approach is to focus on organisms for which current rates of extinction exceed those expected from habitat loss. Amphibians are a case in point. Thousands of species have declined, and hundreds are on the brink of extinction or have already vanished 13 . The Global Amphibian Assessment (GAA) lists 427 species as critically endangered, including 122 species that are possibly extinct 13 . A majority of the former, and nearly all of the latter, have declined even in seemingly undisturbed environments. The causes have remained unclear, in part because of their complexity 1416 . Although pathogens are implicated 1428 , their relationship to environmental change is poorly understood. Here we test the climate-linked epidemic hypothesis 2934 , which predicts declines in unusually warm years but does not assume a particular disease or chain of events. Recent studies have considered this idea 15,18,21,23,28 , yet data have not permitted a geographically broad test that examines landscape alteration, global warming and climate fluctuations on the timescale of El Nin...
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This note was uploaded on 08/06/2008 for the course ESM 219 taught by Professor Holden during the Fall '07 term at UCSB.
- Fall '07
- Global Warming