Cedric the Tasmanian devil is gone, but his DNA lives on.
Scientists today report the genome sequence of the Tasmanian devil, which they obtained by sequencing the genomes of Cedric and Spirit, two devils who died from the facial tumor disease that is driving the devils to the brink of extinction. The researchers, led by Webb Miller and Stephan Schuster of Pennsylvania State University in University Park and Vanessa Hayes of the J. Craig Venter Institute in San Diego, Calif., hope their work will contribute to efforts to help save the Tasmanian devil from the tumor disease.
The facial tumor disease is passed by contact between animals. It has killed up to 90 percent of animals in some areas of Tasmania and is spreading across the devils’ entire habitat.
Researchers think that the devils can’t fight off the facial tumors because their bodies do not recognize the cancer as foreign, and therefore make no attempt to fight it off. Some scientists have hypothesized that the problem is getting worse as the disease culls their population, further eliminating genetic diversity that could provide resilience against the disease.
But the researchers report today found that this probably isn’t true. They analyzed genetic diversity in museum specimens and living devils and found that 100 years ago, the devils were not much more genetically diverse than they are today.
Most sequencing projects focus on human health, but the researchers behind today’s work say they wanted to show that genome sequencing could be used to aid wildlife conservation as well. “The idea is to save a species, not to do a ‘post-mortem’ on it,” Schuster said in a statement.
The researchers say their data could be used to help inform the effort to save the devils, by guiding which animals should be bred together to maintain maximum genetic diversity in captive populations. However, the devil captive breeding program, run by the Tasmanian and Australian governments, is currently not using data from the genome project. Miller said this was “too bad, because that was our reason for doing the project.”
The genomes were sequenced using two “next-generation” DNA sequencing machines sold by Illumina, of San Diego, Calif., and Roche Diagnostics, of Indianapolis, Indiana. Although the team sequenced DNA from Cedric and Spirit two years ago, it took a much longer time to assemble the genetic data into a finished genome and analyze it, because next-generation sequencers read out DNA in small snippets, and it is still a challenge to string those snippets together into a whole genome and make sense of them.
“[A]lthough deep coverage of a vertebrate genome can now be generated in 1 [week] on a single instrument, methods for effectively using the data have not kept pace,” the team notes.