The Tasmanian Devil Comeback Story: U of I Lab Combines Genetic Research With Conservation
Tasmanian devils, an iconic marsupial found only on the island of Tasmania, seemed to be on their last leg a decade ago.
A bizarre transmissible cancer spread through biting — something the carnivorous devils do a lot — was wiping out populations.
What has happened since, according to research by a University of Idaho professor and his colleagues, has been nothing short of remarkable.
Devil populations are making a slow comeback, and research shows that Tasmanian devils are likely to persist because the creatures in a short period have developed a resistance to the disease.
“We’re using genomic data to explore how the rate of the spread of the cancer has changed,” Paul Hohenlohe, an associate professor in U of I’s Department of Biological Sciences said. “The rate of spread has slowed down to where it looks like the prevalence of the disease will start to decrease.”
The cancer, called devil facial tumor disease (DFTD) which forms growths on the faces of the Tasmanian devils, was discovered almost 25 years ago. Tasmanian devils bite each other often in the face, as part of their social interactions.
Since its initial discovery in the 1990s, DFTD has spread rapidly across the devil’s range. The total number of devils in the wild has decreased by about 85%, resulting in predictions that wild devil populations would not survive.
The downward spiral spurred researchers into action. Captured devils unaffected by the cancer were reared with a plan to release them into the wild to prevent extinction.
Researchers, however, recently used an approach called phylodynamics — also used to track the COVID-19 pandemic — to reconstruct the evolution and spread of the tumor through devil populations over time. They found surviving populations have adapted.
“We’ve looked at genetic resistance and the rapid evolutionary response in devils, and there’s evidence of genetic variation for survival in the face of the disease,” Hohenlohe said. “That means that devils can adapt to the disease and persist.”
What now concerns scientists like Hohenlohe is whether the release of unaffected devils into the wild will have a detrimental effect on populations that are developing resistance to DFTD.
“We expected wild populations to die out and would have then recolonized with the captive ones,” Hohenlohe said. “Releasing captive individuals now can have a negative effect and change the dynamics of the disease spread.”
Hohenlohe, who earned his Ph.D. in evolutionary genetics, applies his lab’s genetic research to conservation biology.
What researchers are learning about the genetic evolution in devils, Hohenlohe said, can be directly applied to management.
“We’re making specific recommendations on how captive and wild populations should be managed based on what we know about the disease,” he said.
Hohenlohe, who grew up in Washington, D.C., and moved west to attend graduate school in Washington, said he became interested in applying molecular research to conservation while working on rare species for the Forest Service and Bureau of Land Management.
His U of I lab integrates genetic research with on-the-ground conservation management.
“We’re combining evolutionary genetics with applied conservation research,” Hohenlohe said.
The Tasmanian devil studies were conducted in conjunction with Washington State University. Future research could have implications in the biomedical and health fields, he said.
This project was funded to Washington State University by the U.S. Department of Health and Human Services (HHS) under award R01GM126563. The total project funding is $2,324,299.00 of which 100% is the federal share.
Article by Ralph Bartholdt University Communications and Marketing
December 2020
