# the spread of chytrids (continued from lehmanni)



## Rain_Frog (Apr 27, 2004)

I do agree Corey about the breeding idea. But I also theorize that amphibians that aren't "one hit KOed" like dart frogs and many native amphibians have more time to adapt to chytrids by the process of evolution....if their habitat isn't destroyed so much, reducing their gene pool and population.

I believe I read an article about the intensive project to restore the critically endangered corroborree frogs (looks like a fire salamander crossed with a bumble bee toad) of Australia are showing some signs of resistance now to the infection, but there numbers have plummetted so much, and the additional problems of global warming, pollution, habitat destruction, etc. making the less than 200 wild frogs look bleak, as immunity takes a long time to achieve.

I also think what's not being addressed, that I told OneTwentySix (Peter) that Xenopus are probably not the only main carriers.

What's being overlooked, many South African organisms in general could harbor it. Plants like geraniums originally came from South Africa. Chytrids could have hitched a ride in the soil when plants were collected and taken back. I know many non native blind snakes have found there way in the pots of many tropical plants taken to far away islands.

Has there been any studies of immunity of chytrids in Hyperolius and Kassina? That'd be an interesting find because many species of Hyperolidae live right around Xenopus.


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## Rain_Frog (Apr 27, 2004)

deleted


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## Ed (Sep 19, 2004)

Based on the reports, when chytrid moved into an area it typically is about three years before really massive deaths begin to occur although large scale die offs can occur in metamorphs (but these can be readily missed unless you are at the site when the metamorphs leave the water). 

In addition, chytrids as a family have a world wide distribution (see http://bama.ua.edu/~nsfpeet/Biogeograph ... ataset.htm) the unusual part is that with this species is that it is the only species to parasitize a vertebrate. This species has not been documented to infect any other vertebrate than amphibians and has been found in amphibian samples (Xenopus laevis) as far back as 1938 (see the article listed in the paragraph below for reasons why it may not have been documented back even further). Amphibians are pretty much the major method of transference between the different continents (I can't lay my hands on it at the moment but see Daszak, P., Berger, L.; Cunningham, A.A.; Hyatt, A.D.; Green, D.E.; Speare, R.; 1999; Emerging infectious diseases and amphibian population declines Emerging Infectious Diseases 5:735-748) for the reasoning and documentation behind it. It is believed that is came out with Xenopus and was spread via the laboratory and pet trade, eventually infecting axolotls (A. mexicanum) and American Bullfrogs (R. catesbiana) which were also exported for different reasons globally which has helped expand the range of the fungus. 


At this time, it is theorized that the chytrid is initially locally spread through the area once it has been introduced into the waterways (streams, ponds, rivers) and that the amphibains take it away from the water ways and contaminate other areas with it (this is anecdotally supported by reports that some species that do not ever coming to the ground surviving in some areas despite a total population destruction) and has been documented in some species like Ambystoma tigrinum. 

Chytrid (by which I mean B. dendrobatidis) has been shown to be common in frog species from Ghana, Kenya, South Africa and Western Africa ( Weldon, Che; du Preez, Louis H.; Hyatt, Alex D.; Muller, Reinhold; Speare, Rick; 2004, Origin of the Amphibian Chytrid Fungus, Emerging Infectious Diseases 10(12)). As of 2004 it has been documented in three species of Xenopus (laevis, gilli and tropicalis) and trppicalis has been docmunented to die from chytrid in captivity. 

Now as to the survivorship of species post chytrid involvement: (Corroboree toads (Pseudophryne corroboree) appear to be as sensitive to it as Atelopus from what I remember and are not a good example) there is a paper on it, and it indicates that depending on the species, that a population can persist with an endemic infection that is seasonally variable (see Retallick, Richard W.; McCallum, Hamish; Speare, Richard; 2004; Endemic infection of the amphibian chytrid fungus in a frog community post-decline; PLOS Biology 2(11) e351). However, this paper doesn't indicate anything about survivorship of metamorphs (which are known to have high mortality rates due to chytrid in infected populations) and the long-term viability of the infected population. Another potential issue with the paper is that the study site is that the anurans have access to temperatures that exceed 23 C and can reach 37 C so microhabitat usage and/or basking could allow for the anurans to seasonally clear the fungus and the authors admit to using light microscopy examination of collected toe tips which would allow for light infections to be missed. 
What people are hoping to have happen is that chytrid and the anurans coevolve (ala myxomatosis and rabbits in Australia) and this does not appear to be happening. What may be happening is that some populations may be initially more resistant and or have behaviors that allow them to resist the fungus in most situations (for example Bullfrogs (Rana catesbiana) are known to be carriers in the wild for chytrid (a frog that is known to bask...) but is known to have mortalities from chytrid when farmed) unless some other stressor is then applied to the frog reducing its immune response. 

This is an ongoing issue and not all of the answers are clear as of yet, but the data as to the origin in Africa is pretty solid. 

Ed


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## Rain_Frog (Apr 27, 2004)

BTW, what was "deleted" was a link to the new New York Times article about global warming as a larger cause of amphibian decline, but i deleted it because Mouse posted one in the lounge (which I didn't notice).

But anyhoo, what are your thoughts Ed that global warming is a bigger factor in decline?

I can see the logic that a drier climate can cause more amphibians to crowd around more limited water sources, spreading infection. 

Perhaps constant problems in the environment from global warming causes the animal's immune system to be suppressed?

A little OT, but I believe Justin Yeager said that the Atelopus varius population is not viable and they will probably go extinct in the next year (I don't believe Atlanta Botanical gardens has finished their project working with spumarius first)


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## Ed (Sep 19, 2004)

Given that we went through a fairly major climatic shift about 10,000 to 12,000 years (ice age) as well as the little ice age beginning about 500 or so years ago without the kinds of loss we are seeing at this time, so I'm skeptical at this time but then I haven't seen the data in the original article in Nature magazine. Until I read that one, I'm not sure I have an opinion. 

Was he talking about A. varius or A. zeteki? At the moment, given the current development and decline seen in the zeteki sites, I suspect that this species will also go out in the next couple of years. 

As for ABG and the spumarius, I can't fault them too much as I haven't gotten eggs from mine either. 

Ed


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## Rain_Frog (Apr 27, 2004)

Corey told me this in chat one evening. Basically, the (varius) population is not viable...in the wild. I'm not sure what that means.

I'm sure, because the zoos are having success with zeteki that they will probably still exist, but probably no longer in the wild. Most likely the future of most of the mantellas due to chronic habitat loss. But nobody that I'm aware of is working with varius.

Do varius still exist in Panama and Columbia though?


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## Ed (Sep 19, 2004)

As far as I know, A. varius is only still found in Costa Rica. As for its viability there, it depends on if development gets in or chytrid. A small number of Atelopus maybe all that is needed to repopulate a region due to the large clutch size. 


Ed


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## Guest (Jan 17, 2006)

I think people have my words a bit twisted. A. varius from Costa Rica I have not seen for a few years, but I hear there are some reminants left. A. varius from Panama I believe has now pretty much been wiped out by Chytrid. A. zeteki I will see later this year, but from what I hear this is probably one of their last two (maybe) years. Many of their populations have been hit now, and things are about over. Atelopus sp. from Ecuador that I filmed is also on their last leg. I think they are about in the same boat as A. zeteki-- maybe two years tops. I also worry in the immediate future about A. pulcher-- well ALL Atelopus really. I am applying for filming grants to try to film all remaining Atelopus ASAP. I am also currently making plans for a long visit to Colombia as they have the majority of the remaining species-- though many are dangerous to see. I have not been very active online lately because of these and some other work-related things. I'm sure you all understand. As always, I will post significant updates when I have them. We are just finishing the updated subtitles, but otherwise our first film is finally done and polished. When I can afford it, I will do a larger commercial run. It is around 37 minutes and is in both English and Spanish. If any teachers, universities, or institutions want copies before the larger commercial run, please contact me. I have been selling very few copies of the final film edit, but with the old (rushed) subtitles, if someone can't wait for the final edited subtitles, you can also contact me. These are limited in number.
Justin


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## Rain_Frog (Apr 27, 2004)

Justin, so Atelopus varius (the frogs that you rediscovered and took photos of) are gone now altogether?!?  

How are Atelopus flavescens doing? I still think they are the most stunning atelopus (at least the orange and pink kind), but aren't they the least affected because they are lowlanders?

How many lowlander atelos are there? I haven't seen too many pics of those kind, just the highlanders which have received so much conservation attention.


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## Guest (Jan 18, 2006)

The A. varius I photographed were the ones from Costa Rica-- see above. I will be filming A. zeteki in Panama in May. The grant has now been submitted for the filming project, so if you like Atelopus say a little prayer or some form of luck that you do that I will win the grant. A. flavescens from what I hear are still doing well-- and there are several populations of them (and color variants). If I win the grant, I will be filming them as well shortly. As for how many are left-- no one really knows. I have heard a recent estimate there may be 30 species alone left in Colombia-- much more than I have been thinking, but we don't know. I honestly feel that if there are 30 species left total that would be a lot. I guess time will tell when we investigate them more-- and by the time we figured out how many were left, most of them will be gone. It's not a cheerful topic. In any event, I will keep people posted as I hear new things. 
Justin


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