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Although cancer rarely acts as an infectious disease, a recently emerged transmissible cancer in Tasmanian devils (Sarcophilus harrisii) is virtually 100% fatal. Devil facial tumour disease (DFTD) has swept across nearly the entire species' range, resulting in localized declines exceeding 90% and an overall species decline of more than 80% in less than 20 years.
Researchers have found that Tasmanian devils have developed some genetic resistance to the disease in just four to six generations.
Evolving resistance within so few generations is rare for vertebrates, says Beata Ujvari, an evolutionary ecologist at Deakin University in Melbourne, Australia, who was not invovled in the study. Australia's rabbit population quickly developed resistance to myxomatosis, a fatal viral infection. But it took 50–80 generations to do so.
The devil facial-tumour disease jumps from one Tasmanian devil to another when they bite each other during social interactions.
http://www.nature.com/news/tasmanian-devils-show-signs-of-resistance-to-devastating-facial-cancer-1.20508
http://www.nature.com/ncomms/2016/160830/ncomms12684/full/ncomms12684.html
(Score: 1, Interesting) by Anonymous Coward on Friday September 02 2016, @01:26PM
Perhaps the thing that makes the cancer transfer is a broken gene that 80% of the population had.
If the working version gave some small advantage, that might explain why it was still around.
Hopefully they saved some samples from the broken part of the population and can figure this out with gene sequencing.
If they did not see the gene change which could take a long time, but they did see a selection given the change which was pretty quick;
then perhaps this isn't a case of 'evolving resistance' because resistance was already there.
It could be instead a case of the quick half of evolution.
If the other version of the gene hadn't already been there, and so the species had to wait for all of evolution to proceed, it seems likely that the species would not be here.
There is a lesson here in how for fast our species could change due to an unexpected biological appearance.
One hopes he necessary genes will be somewhere in the pool when the need shows up.
(Score: 2) by Joe Desertrat on Friday September 02 2016, @08:48PM
If the working version gave some small advantage, that might explain why it was still around.
It is possible that in previous manifestations of the cancer that it struck more aged animals, taking out individuals that were past prime breeding age and which had already passed on their genes. Since there are greater stresses on the population due to a variety of environmental factors, the cancer may be manifesting itself earlier now. Or, if the gene for susceptibility to the cancer is recessive, it is possible that an already struggling indigent population of the animals is forcing a smaller gene pool together. There are a lot of different factors which could account for the rise in the cancers, let us hope the remaining population has enough variability to ensure the survival of the species.