A recent publication by the Save the Tasmanian Devil Program announced that a second cancer, dubbed DFTD2, was identified in several individuals. There have only been two species to ever develop a transmissible cancer – a single species being susceptible to two of these cancers in almost unfathomable. There is now a high likelihood that the species will go extinct in the wild and management programs are redirecting funds to captive programs to reflect this difficult decision.
What are Tasmanian Devils and DFTD?
The Tasmanian devil (Sarcophilus harrisii) is the largest carnivorous marsupial, found only on the island state of Tasmania, Australia. They are an endangered species with a recorded decline of over 60% in the last decade. The devil is under immense ecological pressure due to a rare infectious disease known as Devil Facial Tumor Disease (DFTD).
The devil’s name is partly derived from the highly aggressive nature of the animal; biting in defense, play, and courtship is part of their daily routine. In cruel irony, saliva through biting is the vehicle of transmission for DFTD. When an uninfected devil is bitten, the disease manifests itself in the animal and causes rapid cell division and tumor growth on the face. Ultimately, the tumors inhibit the ability to eat and the devil dies of starvation.
This disease is exceptionally unique in that it is not a viral disease, but instead a transmissible cancer – one of only two ever recorded. Furthermore, DFTD is particularly anomalous because not only is this cancer transmissible, but immortal. The cancer is a parasitic organism in itself; DFTD1 has its own DNA that is discerned to belong to the first female devil discovered to have the disease, known as an immortal cell line. The recently discovered DFTD is rooted to an unknown male. Human activity annihilated the mainland populations and pushed the few remaining survivors back to the indigenous Tasmania. Now, there is so little genetic diversity, they have no mechanism to create a natural resistance to DFTD. (Images of the disease are very graphic. To view click here, here, and here.)
However, one may ask, if the devil can go extinct on the mainland, why is it so crucial to protect the few remaining in Tasmania? The answer is complex, much like Tasmania’s ecosystem. Essentially, the devil is a scavenger species and without it disease would spread rapidly as no other animal is able to fill this niche. In other words, the ecosystem of Tasmania could fall into chaos without direct intervention to save the species.
Current efforts to save the species are to create quarantine facilities with captive breeding programs for future reintroductions which have been moderately successful in the past. This species is a hotspot for research in several fields and there has been great progress in vaccine development for DFTD1 (prior to the discovery of DFTD2). The Save the Tasmanian Devil Programme is continuing to monitor wild populations in hopes to keep the species alive despite this devastating news.
For two months this summer, I will be working with the Save the Tasmanian Devil Program at their Cressy facility; the largest captive breeding center for Tasmanian Devils in the world.