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The proximate cause of frog declines?


Arising from: J. A. Pounds et al. Nature 439, 161–167 (2006)10.1038/nature04246; Pounds et al. reply

Pounds et al.1 argue that global warming contributes to amphibian declines by encouraging outbreaks of the chytrid fungus Batrachochytrium dendrobatidis. Although our findings agree with the climate-linked epidemic hypothesis1,2,3,4, this pathogen is probably not the only proximate factor in such cases: in the Trasimeno Lake area of Umbria in central Italy, for example, the water frog Rana lessonae first declined in the late 1990s, yet chytridiomycosis was not observed until 2003 (refs 5, 6). Here we show that the chytrid was common there throughout 1999–2002, in a previously unknown form that did not cause disease. We therefore think that the focus by Pounds et al. on a single pathogen is hard to justify because the host–parasite ecology is at present so poorly understood.

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Figure 1: A newly discovered form of the chytrid fungus Batrachochytrium dendrobatidis on the skin of the water frog Rana lessonae.


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Rosa, I., Simoncelli, F., Fagotti, A. et al. The proximate cause of frog declines?. Nature 447, E4–E5 (2007).

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