# Reconciling the Roles of Disease and Climate Change in Amphi



## Matt Mirabello (Aug 29, 2004)

http://biology.plosjournals.org/perlser ... 60072&ct=1

"Additional analyses found no evidence to support the hypothesis that climate change has been driving outbreaks of amphibian chytridiomycosis, as has been posited in the climate-linked epidemic hypothesis."


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## elscotto (Mar 1, 2005)

For all the mileage that Pounds et al have gotten out of their Nature papers, there sure are a lot of people who disagree.


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## Matt Mirabello (Aug 29, 2004)

elscotto said:


> For all the mileage that Pounds et al have gotten out of their Nature papers, there sure are a lot of people who disagree.


please discuss!


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## elscotto (Mar 1, 2005)

Well, Pounds and his colleagues have gotten quite a bit of attention through several Nature papers (e.g., Pounds et al., 1999; Pounds, 2001; J. Alan Pounds and Robert Puschendorf, 2004; Pounds et al., 2006). In all of these papers the authors try to very strongly tie global warming trends to amphibian declines. As you're likely aware, Nature is one of the most respected ecology journals, and one of the most read, and as such one of the most influencial journals within the scientific community. The authors assert climatic fluctuations are driving chytrid outbreaks, and thereby amphibian population crashes, and they rely most strongly on evidence from around Monteverde, Costa Rica. In some respects they make a strong argument for their hypothesis, but support for the idea seems to describe what might be happening within very small geographic regions, and it seems very unlikely, at least to me, that their hypothesis would hold up over a global scale. With a paper title such as "Widespread amphibian extinctions from epidemic disease driven by global warming" I think they are over-stepping (scale) any significance of their findings. For example, the wave of chytrid-related frog deaths appears quite steady and predictable across Panama. For the most part, it doesn't matter what the weather is doing, the disease is going to wipe out the frogs when it contacts them; this has been going on continually since the late 90's. I think as more long-term data come in from other regions it will become increasingly apparent that once introduced, the fungus will spread fairly predictably through the frog communities. Anyways, my main point being that a number of things are going on with this disease, and it is obviously catastrophic to amphibians. I feel that continually following this atelopus/climate change/disease susceptibility hypothesis, when there is the possibility to generate more comprehensive, larger-scale explanations and solutions for the disease spread, (that is, globally and across very diverse frog families), might be an ill-advised.


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## bbrock (May 20, 2004)

That's a great synopsis. But for those who may be less familiar with the debate, I think it is important to understand that Lips et al. are not suggesting that climate change has no role in the chytrid epidemic. It's been awhile since I read the paper, but I believe they even support the climate change mediated mechanism that Pounds et al. describe. That being that warming of the oceans increases evaporation and subsequent fog layers in the cloud forests which extends the amount of cool and moist conditions where the fungus appears most destructive. Lips et al merely state that they find no evidence that climate change explains the observed patterns of outbreaks. As was already stated, the effects of climate change appear to be more geographically limited, but that does not mean that climate change is unimportant in the chytrid story.


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## Rain_Frog (Apr 27, 2004)

Like Brent said, I think climate change weakens frog populations and makes them more susceptible to disease, like the altrazine pesticide theory (although some sources point out that altrazine has caused no harm to amphibian immune system).

But, I do agree that something else is pulling the trigger (like the climate change hypothesis), but chytrid is the bullet killing frogs.


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