There are only four different kinds of transmissible cancer in the animal kingdom.
Tasmanian devils have punched the golden ticket, having two of these four kinds. It was predicted that the transmissible cancer would wipe out the entire species. However, the Tasmanian devils persisted.
Andrew Storfer, a researcher from Washington State University, and Paul Hohenlohe, a researcher at the University of Idaho, set out to discover why.
The cancer first developed in 1996 and it spread rapidly across the species, with an initially high mortality rate, Hohenlohe said. Before 1996 there were no observed cases of the cancer — it developed practically out of nowhere.
“We set out to ask if there’s a genetic variation for resistance, and there’s the possibility that the species can evolve to resist the disease,” Hohenlohe said.
Hohenlohe and Storfer asked just the right question. Now, with modern technology they also had the means to test it.
“We hypothesized that the devils evolved, or the tumors evolved or both,” Storfer said. “We had samples from before the disease and after, and we scanned both genomes and looked for frequencies in certain genetic variances.”
The sudden persistence of this cancer raised a lot of concern with the public, especially in regard to the conservation of the Tasmanian devil.
“People were really worried about this iconic species,” Hohenlohe said. “There was a large push for field work and collecting samples.
It’s a big international effort, he said, with collaborators from the United Kingdom and Australia as well.
For Storfer, this research all started when he was on sabbatical in Australia in 2008. He said he was invited to a seminar in Tasmania, and there they agreed that his expertise would be beneficial to the research.
The research scanned across the genome of three populations of Tasmanian devils. They searched for genetic differences in the survivors of these populations.
“We saw evidence of rapid evolution in only four to six generations,” Storfer said. “We now have candidate genes to explore relationships.”
Storfer said this is the best news the devils could receive. This led Storfer and other researches to believe the animal will not go extinct.
Hohenlohe said the biggest challenge so far is dealing with the massive amount of data. With modern technology, they can sequence large amounts of information, but the analysis still takes a long time.
In the future, members of the project are going to scan more populations. The goal of this is to link more genes to resistance. This also has implications for cancer and evolution research in general.
“It has the potential to give insights into other types of cancer,” Hohenlohe said.
It has the potential to further demystify evolution research, Storfer said, because it gives researchers insight into general evolution outside the realm of cancer. Researchers are currently looking into the second type of transmissible cancer that Tasmanian devils have as well.
“The fact that two of these (cancers) happened in one species, you can’t really explain it by chance,” Hohenlohe said.
Carly Scott can be reached at