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Are Tasmanian Devils Fighting Their Way Out of Extinction?

Stopping Devil Facial Tumor Disease

Tasmanian devil with Devil Facial Tumor Disease
A Tasmanian devil is captured exhibiting advanced signs of Devil Facial Tumor Disease Oct. 10, 2005 near Fentonbury, Australia. Adam Pretty/Getty Images

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DVTD was first observed in 1996, when wildlife photographer Christo Baars noticed something odd about certain Tasmanian devils he watched through his camera lens. Camped out in Mount William National Park in Tasmania, Baars spotted large, gruesome lumps around the devils' mouths and necks [source: Quammen].

Scientists have found only a handful of cancers that are contagious like DFTD. Viruses can trigger cancer, but rarely does cancer itself act as a virus, jumping among individuals. That makes DFTD not only easy to catch, but also highly fatal due to the genetic isolation among Tasmanian devils. The marsupials live in the wild only in Tasmania, which has resulted in a lack of genetic diversity among the species. In addition, the genetic sequencing of DFTD is so similar to that of a Tasmanian devil that the animal's body doesn't recognize the virus as a threat. Consequently, the animal's immune system doesn't respond to fight off the virus before it develops into full-blown cancer.

So, what's the best way to stop it? Scientists hoped that a devil named Cedric from the west held the key to halting the cancer. Immunologists injected the Tasmanian devil with live tumor cells, and after five months, Cedric's body produced antibodies to fight the virus. Scientists therefore hypothesized that Cedric might have a slightly different genetic coding that triggers a stronger immune response. By cracking that genetic code, scientists could develop a potential method for identifying and quarantining other resistant devils. After reintroduction into the wild, the immune devils would breed and form a stronger population. But Cedric ended up dying in 2010 after developing tumors a year after he appeared to have resisted the disease [source: Nature].

Vaccinations seem like another way to stop Devil Facial Tumor Disease (DFTD) from infecting more Tasmanian devils. Numerous studies had been done to determine whether developed vaccines were successful at eliciting an immune response. Finally, in March 2020, 19 immunized devils were released into Narawntapu National Park and will be monitored to determine immunization success. Most had already shown signs of immune response in the lab [source: University of Tasmania].

Back in 2003, the Tasmanian State Government set up a Save the Tasmanian Devil Program and created an insurance population, made up of 700 animals across 44 institutions (in Australia, New Zealand, Europe and America). The species is reported to do well in captive breeding situations, and as such the effort has been successful. The program also spearheaded a successful campaign urging motorists to slow down at night and created virtual fence devices that warn animals of approaching cars. More than 350 devils are killed each year by motorists.

If Tasmanian devils were allowed to disappear entirely, it would have a deep impact on the island's ecology. The carnivorous marsupials keep the cat and fox population in check. No more devils would mean a spike in the number of those predators, which would spell the demise of more than a dozen other species, including some birds and lizards. And as scavengers, devils also remove sick and dead animals from the landscape.

Fortunately, things appear to be looking up for Tasmanian devils. Only very recently, researchers have begun to note that animals in the wild appear to be fighting off tumors entirely, so a devil that previously had a tumor might not have one only a few months later [source: Gough].

Natural selection also appears to be playing a role in the leveling out of this endemic disease, as the Tasmanian devils who are capable of fighting off the disease are the ones reproducing, causing a much-needed ripple effect. In fact, in 2019, researchers forecast a 57 percent chance of DFTD fading out within the next 100 years versus a 22 percent chance of the disease coexisting [source: Timmins].

Although surprising, this quick and nimble adaptation of the species to the disease is certainly in keeping with their overall reputation as quick and nimble predators. Still, although the decline appears to be leveling off, the devil population is still nowhere what it was in the 1990s.

Last editorial update on Apr 29, 2020 03:48:47 pm.

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Sources

  • "Bedeviled by Disease." The Washington Post. April 15, 2008. (Dec. 17, 2008) http://www.washingtonpost.com/wp-dyn/content/article/2008/04/14/AR2008041402486.html
  • "Dying Tasmanian devils turn to teen pregnancies." New Scientist. July 19, 2008. (Dec. 17, 2008)http://www.newscientist.com/article/mg19926655.600-dying-tasmanian-devils-turn-to-teen-pregnancies.html
  • Gough, Myles. "Bringing the Tasmanian devil back to mainland Australia would restore ecosystem health." Phys.org. Aug. 11, 2015 (April 20, 2020) https://phys.org/news/2015-08-tasmanian-devil-mainland-australia-ecosystem.html
  • "Possible vaccine for dying devils." Australian Geographic. July - September 2008.
  • National Geographic. "Tasmanian Devil." 2020 (April 20, 2020) https://www.nationalgeographic.com/animals/mammals/t/tasmanian-devil/
  • Quammen, David. "What's Killing the Tasmanian Devil?" Yale Environment 360. Oct. 16, 2008. (April 20, 2020) https://e360.yale.edu/features/whats_killing_the_tasmanian_devil
  • ScienceDaily. "Tasmanian Devil Cancer Unlikely to Cause Extinction, say experts." Jan. 23, 2019 (April 20, 2020) https://www.sciencedaily.com/releases/2019/01/190123191634.htm
  • Tasmanian Government. "Tasmanian Devil." 2020 (April 20, 2020) https://dpipwe.tas.gov.au/wildlife-management/fauna-of-tasmania/mammals/carnivorous-marsupials-and-bandicoots/tasmanian-devil
  • Timmins, Beth. "Tasmanian devils 'adapting to coexist with cancer.'" BBC News. March 30, 2019 (April 20, 2020) https://www.bbc.com/news/science-environment-47659640
  • Trofimov, Yaroslav. "Tasmanian Devils Get Reprieve in Australia's Old Penal Colony." The Wall Street Journal. May 28, 2008.
  • University of Cambridge. "Tasmanian devil facial tumour disease." 2020 (April 20, 2020) https://www.tcg.vet.cam.ac.uk/about/DFTD
  • Woods,Gregory M and Samantha Fox, Andrew S Flies, Cesar D Tovar, Menna Jones, Rodrigo Hamede, David Pemberton, A Bruce Lyons and Silvana S Bettiol. "Two Decades of the Impact of Tasmanian Devil Facial Tumor Disease." Integrative and Comparative Biology. Dec. 2018 (April 20, 2020) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6927850/

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