Tasmanian devils are a tenacious mammalian species, the largest carnivorous marsupial left on Earth. They've managed to eek out an existence on the Australian island of Tasmania, where they've remained relatively sheltered from threats that have wiped out other marsupial species throughout the rest of the Australian continent.
But now there's a new threat that many researchers fear could be the beginning of the end for this charismatic species: a highly contagious form of facial cancer that was fatal to nearly 100 percent of all devils that caught it when it was first detected in 1996.
There's good news, though. Tasmanian devils might be an evolutionary relic in many ways — a holdover from a time when large carnivorous marsupials were more commonplace — but there's evidence they are currently evolving, and rapidly, in response to this cancer scourge, reports Phys.org.
An international team of researchers from the United States, Great Britain and Australia surveyed devil DNA that has been collected and stored since before the facial cancer spread throughout the devil population. They were able to identify two small genomic regions in the samples that exhibited significant changes in response to the disease. These regions are known to be related to immune function in other mammals, indicating that Tasmanian devils might be in the process of evolving a resistance.
Though devil populations have been reduced by up to 80 percent across Tasmania, many of the longest-diseased locations still harbor small numbers of healthy devils. It's unlikely that these stragglers have somehow managed to avoid contact with the disease. Rather, they may represent a new, genetically-resistant group.
The findings offer hope for the species' survival, and researchers are already considering an off-island breeding program to introduce this new cancer-resistance to captive populations, to further offer insurance for the wild population.
“Our study suggests hope for the survival of the Tasmanian devil in the face of this devastating disease," said Andrew Storfer, one of the researchers involved in the study. "Ultimately, it may also help direct future research addressing important questions about the evolution of cancer transmissibility and what causes remission and reoccurrence in cancer and other diseases."