A contagious facial cancer that is almost always fatal has cut a wide swathe through the population of Tasmanian devils since 1996. The disease has reduced the devil population by 80%, and researchers have predicted that the cancer will drive the animals to extinction within decades.
But a study published on 30 August in Nature Communications1 offers hope. 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. And even though the cancer has wiped out up to 95% of some devil populations, small groups of the carnivorous marsupial have managed to hang on.
The researchers wanted to find out how the devils persisted in the face of such a devastating disease. So Andrew Storfer, an evolutionary geneticist at Washington State University in Pullman, and his colleagues sequenced about one-sixth of the devil’s genome using 294 individuals from 3 wild populations. They used samples collected before and after those groups first encountered the facial cancer.
The team found five genes spread across two regions of the genome that seemed to be increasing in frequency throughout the devil populations. Storfer says that two of the genes, CD146 and THY1, are particularly interesting because they help the immune system to recognize foreign cells. Usually, cancerous cells originate in the host, but …