Pharyngula

Tasmanian devils need your help

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We had a seminar from Marco Restani of St Cloud State University yesterday — he’s a wildlife biologist who talked about Tasmanian Devils. Just a little tip: don’t ever invite wildlife biologists or conservation ecologists to give talks. They are the most depressing people in the world, and they really make it hard to hide away from the ugly realities. This talk was no exception: the Tasmanian Devil is in big trouble, and is facing at least two major threats, each of which may be sufficient to wipe them out. And just looke at that guy! He’s adorable! How can you let them go extinct?

The first big problem: the Tasmanian Devil is a marsupial with a limited range, confined to that large island south of Australia. They used to range over the entire continent, but were extirpated from the Australian mainland by, it is thought, the introduction of the dingo. Unfortunately, their refuge on Tasmania has been invaded by foxes (intentionally introduced by people Restani called “jerks”—I think, though, he was choking back some stronger language). This is catastrophic. There has been a major effort to kill off the foxes, but it may be too late, and they may have already established themselves.

The second big problem, and the one that I found particularly fascinating in a grisly, horrific way, is that the devils are being wiped out by serious new disease, Devil Facial Tumour Disease, or DFTD. It sounds awful and it looks worse.

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This disease consists of rapidly proliferating facial tumors spreading across the jaws and face. It kills within months, and it’s spreading across the island at a frightening rate. Restani described some of his random sampling results; overall, about 16% of the devils have these lesions, with some areas showing infection as high as 40%, and others (particularly in the northwest) still disease-free. Think of this — tens of thousands of animals in Tasmania are covered with these lethal disfiguring lesions right now, and will be dying a painful death…before the foxes move in and take over their habitat.

Now I’ve got to really creep you out. This particular disease seems to be unique, with a very unusual cause.

The tumors have been examined cytologically. They, like typical cancer cells, have broken, rearranged chromosomes, exhibiting some fairly complex restructuring of the genetic material. They also have missing chromosomes. This is not at all surprising, and is what is seen all the time in all kinds of cancers.

The weird thing, though, is that all of the devil tumors have the same cytological scrambling. There are some slight differences, but they’re all traceable to small changes in the same common chromosomal reorganization. In addition, one animal was found with a marker in its normal cells that was not present in the cancer cells.

The explanation: these are all allografts. All of the tumors in all of the animals are descended from one original cancerous devil. Devils often fight over carcasses (they’re scavengers), and the idea is that the wounds they suffer are avenues for cancer cells to migrate from one individual to another and colonize and proliferate and bloom into full-blown DFTD.

Got that? It’s an infectious cancer. Cancer cells crawl out of one victim to infest another. It’s the same godawful cancer growing across the entire population.

While that is a chilling idea, it’s also fascinating. It’s a case where a cancer cell has acquired a little more autonomy and has graduated from an accidental, lethal killer of an individual to a kind of parasite that can leave its source host and thrive in others. I’m wondering whether it ought to be given a new species name of its own. Maybe we should be casting a more suspicious eye on HeLa cells, too.

What’s to be done to save the Tasmanian devil? One plan is to move animals to other island refuges. The problem right now is that there are no diagnostic tools to identify infected devils, and all you have to do is move one animal with incipient DFTD, and your refuge is infected. So the approach is to develop assays and, ideally, vaccines against the cancer.

This takes money.

You can donate as an individual — there is a fund set up and even us remote Americans can contribute. We can also make a case to our governments that this infectious disease is worthy of study, and that maybe we should be making an effort to understand this horrible creeping cancer now.

There’s another avenue for public pressure to work, too. Where did you first hear about the Tasmanian devil? Who has profited most from the devil?

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Right. Warner Bros. and LooneyTunes. You’ve gotta love Taz. Now imagine Taz with painful, suppurating growths all over his face. Imagine watching the cartoons with your kids and having to explain that the Tasmanian devil is extinct, but Warner Bros. still makes a few bucks off the line of stuffed toys and the cartoons. It kind of takes the joy and the funny out of the shows if you think of the last Taz starving to death in the brush as an aggressive tumor consumes his face. Apparently, there is some Taz plush toy somewhere that Warner Bros. markets and gives a cut of the profits to devil research, but I haven’t been able to find it, and it’s not quite enough anyway.

It might be a good idea for a lot of people to hint to Warner Bros. that if they want a positive corporate image, here’s an opportunity for them to make a difference.

Comments

  1. #1 Brownian, OM
    November 16, 2007

    Wow.

    Thanks for this post, PZ. It’s chockablock with all kinds of crazy stuff I didn’t know before.

    After reading about HeLa cells, I’m going to be much more careful with my discarded, er, biological matter.

  2. #2 David Marjanovi?, OM
    November 16, 2007

    Youre talking about eliminating a disease spread by virus in wild animals.

    It’s not a virus.

    ————-

    So the presence of foxes in Tasmania is now confirmed? I am getting angry. Really angry.

  3. #3 David Marjanovi?, OM
    November 16, 2007

    Youre talking about eliminating a disease spread by virus in wild animals.

    It’s not a virus.

    ————-

    So the presence of foxes in Tasmania is now confirmed? I am getting angry. Really angry.

  4. #4 David Marjanovi?, OM
    November 17, 2007

    In one? generation, they went from being dependent subcomponents of metazoan bodies to being INDEPENDENT propagules. They have formed a new phylum!

    Doesn’t follow. “Phylum”, like all ranks except “species”, has no definition; it’s 100 % subjective.

    And “species” has at least 25 often conflicting definitions, so some say it’s just as subjective.

    Generally evolution is applied to discussions of changes that affect (at the least) populations of individuals.

    Isn’t a cancer a population of cells…?

    As it turns out, Australia is also a continent, and Tasmania is an island to the south of that continent.

    Not in geological terms.

  5. #5 David Marjanovi?, OM
    November 17, 2007

    In one? generation, they went from being dependent subcomponents of metazoan bodies to being INDEPENDENT propagules. They have formed a new phylum!

    Doesn’t follow. “Phylum”, like all ranks except “species”, has no definition; it’s 100 % subjective.

    And “species” has at least 25 often conflicting definitions, so some say it’s just as subjective.

    Generally evolution is applied to discussions of changes that affect (at the least) populations of individuals.

    Isn’t a cancer a population of cells…?

    As it turns out, Australia is also a continent, and Tasmania is an island to the south of that continent.

    Not in geological terms.

  6. #6 David Marjanovi?, OM
    November 17, 2007

    I have a serious question: Why should we care?

    1. Because it’s our fault (not the cancer, but the foxes and perhaps the bottleneck).
    2. Because it would be a pity. Do you have no idea of the sheer awesomeness of Tassie devils?

  7. #7 David Marjanovi?, OM
    November 17, 2007

    I have a serious question: Why should we care?

    1. Because it’s our fault (not the cancer, but the foxes and perhaps the bottleneck).
    2. Because it would be a pity. Do you have no idea of the sheer awesomeness of Tassie devils?

  8. #8 David Marjanovi?, OM
    November 17, 2007

    One thing we should of course be doing is initiating a massive fox cull.

    Apparently the presence of foxes in Tasmania still isn’t quite confirmed.

    (On the mainland, though, foxes have caused enough mischief…)

  9. #9 David Marjanovi?, OM
    November 17, 2007

    One thing we should of course be doing is initiating a massive fox cull.

    Apparently the presence of foxes in Tasmania still isn’t quite confirmed.

    (On the mainland, though, foxes have caused enough mischief…)

  10. #10 Abigail Wartella
    March 9, 2008

    I hate that this is happening to these adorable but fiesty animals!

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