Thursday, November 8, 2012

Evolution of the Devil Facial Tumor Disease

Since the late 1990’s the Tasmanian devil, Sarcophilus harrisii, has been plagued by a contagious form of cancer, known as the Devil Facial Tumor Disease. The facial disease has had a drastic effect on the Tasmanian devil population, leading to the species being added to the endangered list in 2008. Since 1996, the contagious disease has killed off roughly 80 percent of the population and could ultimately lead to the extinction of the Tasmanian devil.

The Devil Facial Tumor Disease first presents itself as small lesions or bumps in or around the mouth of the Tasmanian devils. These then grow into large tumors around the mouth and face, which impede the devils ability to eat. More often than not, the infected Tasmanian devils die from starvation, but some also die due to the tumors metastasizing and affecting vital organs. Either way, it is estimated that once an individual contracts the contagious cancer, it usually does not live longer than six months. Although this seems like a short time frame, the problem with this disease being contagious, coupled with the Tasmanian devils biting behaviors, is that it allows time for the cancer to spread further throughout the population.  

Interestingly enough, scientists have been able to trace the cancerous genes all the way to a single female Tasmanian devil. The cancer is highly contagious and has spread through the years through the bites between Tasmanian devils. Unlike previously thought, Devil Facial Tumor Disease does not change the actual genes themselves, but rather, affects how the genes turn on and off.  Furthermore, the interesting aspect about this specific cancer is that it is evolving within the species. Though, it is still unknown whether these changes are causing the cancer cells to become more aggressive or less aggressive, leading to benign tumors. Obviously, if the changes cause the cancer to become more aggressive, it would have a drastic effect on the Tasmanian devil population, which could ultimately lead to the species’ decline to extinction. On the other hand, if the way the genes evolve causes the cancer to become less aggressive, it could possibly give the population of Tasmanian devils a fighting chance.

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