Exploring evolutionary genetics to stop disease

Ornery marsupials about the size of a small dog, Tasmanian devils reign as the dominant carnivore on their native island of Tasmania, 150 miles south of Australia. But in the past 2 decades, these ferocious creatures have faced a lethal threat: a fast-spreading, contagious cancer.

Devil facial tumor disease (DFTD) causes painful red welts to erupt on the animal’s mouth and head. Victims become unable to eat. They either starve to death or suffocate. Spreading like a virus, DFTD has wiped out 80 percent of Tasmanian devils in the wild. Epidemiological studies said that extinction was inevitable.

But some Tasmanian devil populations defied those dire predictions. WSU biology professor Andrew Storfer is probing the secret to their survival. His findings may answer fundamental questions about how disease spreads in both animals and humans.

Comparing DNA, before and after the outbreak

Dr. Storfer is part of an international team of scientists studying Tasmanian devil populations. He and fellow scientists from Great Britain and Australia collected Tasmanian devil DNA from before and after the DFTD outbreak. By comparing genes in the old and new DNA, the team identified genetic variants that didn’t exist before DFTD emerged. The variants appeared in regions of the genome linked to immune function and cancer response.

Dr. Storfer’s findings suggest that Tasmanian devils are evolving genetic resistance to DFTD.

Helping Tasmanian devils and other species

Dr. Storfer hopes that Tasmanian devils with disease-resistant DNA can be bred to enhance the genetic diversity of an off-island captive population. The offspring can be used to reintroduce the species where populations were wiped out by disease.

The research also explores questions about the evolution of cancer transmissibility and causes of remission and recurrence. Answers could protect animals and humans alike.