Tasmanian devils may be evolving to be immune to contagious cancer that has been diminishing the animal’s populations.
The feisty carnivores marsupial is internationally recognized thanks to the Looney Tunes characters of the same name. It has also become an iconic symbol of both Tasmania and Australia.
However, its population has been dwindling dramatically the past twenty years thanks to a strange cancer that is contagious and has killed eighty-five percent of the marsupials.
However, a new study published in the journal Nature Communications has found that the Tasmanian devils are evolving to resist the disease, which means they could save themselves from extinction.
The scientists analyzed DNA samples from more than ten thousand Tasmanian devils that were recollected in a two-decade period.
During the study period, they found out that genetic changes have been happening in certain populations while the disease was quickly spreading.
Andrew Storfer, an author of the research and evolutionary geneticist at Washington State University, stated that once they realized the animals were not becoming entirely extinct, they decided to study the phenomenon.
“Epidemiological models indicated some of these populations – the earliest infected – should already be extinct. But they are currently surviving” said Storfer.
The results of the research
The study concluded that seven “new” genes were the culprits of the Devils’ stronger immune system. These genes had the capacity to attack and destroy the cancerous cell and had become usual in the populations that were being decimated.
The researchers have deduced that there is a direct link between this genetic evolution and the spread of contagious cancer. More than half of the genes appear in other mammals, including humans, and help boost the immune system against cancer.
This means that the study could help to provide more knowledge in cancer remission and recurrence, which would help develop new forms of treatment.
According to Storfer, “the broad implications gives us hope for the survival of the Tasmanian devil. They are evolving genes that may be associated with resistance to the disease.”
The contagious cancer
In 1996, exactly two decades ago, scientists found the first Tasmanian devils that had harrowing facial tumors. These tumors, which began in the head, will quickly spread to the rest of the body in six months, killing the marsupial.
But the unsettling discovery occurred when scientist realize that Tasmanian devils that bit each other appear to develop the disease, which led them to conclude it was a rare type of contagious cancer.
The fact that the animals died so quickly meant they did not reach sexual maturity and died before they could reproduce as they would under normal circumstances.
This caused the populations to dissolve in such a rapid way, that only fifteen percent of all the animals survived.
The genetic evolution came as such a surprise because in 2009, Hamish McCallum, a biologist at Griffith University, published a study in which predicted that the Tasmanian devils in the “red zone” of the disease will become extinct by 2016.
Nonetheless, as the scientific community can clearly see, this did not happen, thanks to the immunity genes, which appeared very quickly in evolution standards: within four or eight generations.
“I am very glad that I was wrong – it appears that the Devils are saving themselves through evolution,” said McCallum.
Recuperation of the populations
Now, the aim is to utilize the research findings to help increase the cancer immunity in captive populations, with the objective to free them and restore the diminished populations.
A genomicist at the University of Idaho, Paul Hohenlohe has stated that the conservation of Tasmanian devils must be a primordial focus of scientists.
“An important part of our work is finding information that can inform management of both wild populations of devils and captive populations. Our goal is to look for genetic variants that convey some resistance to the disease so it may be possible to manage captive populations to ensure that variation is maintained” said Hohenlohe.
The contagious cancer is also evolving
There are only two type of contagious cancer in the world, the canine transmissible venereal and the facial tumors of the Tasmanian devils.
Now, just as the Tasmanian devils are getting immune to their cancer, teams from the Universities of Tasmania and Cambridge have found that there is a new “genetically distinct” cancer.
This new type of cancer also causes tumors on the head and face, but these are substantially different from the first type of cancer, since they have “different chromosomal rearrangements”, making them genetically distinct.
That could mean that the new genes would be useless in front of this new genetic cancer.
Only eight Tasmanian devils from the southeast of Tasmania are carriers of the disease.
In normal circumstances, the Devils live for up to five years and are the world’s largest carnivorous marsupial with their height of 31 inches and weight of 26 lbs.
Sources: Daily Mail