While the hopeful across Tasmania and Australia keep their game cameras charged and ready to capture one on film, scientists announced they have sequenced the genome of the Tasmanian tiger and that information is what they need to bring the thylacine back from extinction (if it’s indeed extinct) and clone a population big enough to return to the wild. However, it may also contain a warning of what to expect.
In an exciting paper published in Nature Ecology & Evolution, lead author Andrew Pask from the University of Melbourne announced that his research team had sequenced the entire genome of the thylacine using DNA from the soft tissue of “a 108-year-old, alcohol-preserved thylacine pouch young specimen” from Museums Victoria. That preserved animal predates the last known thylacine which died in 1936 at the Hobart Zoo. While there are fur and bone samples in many museums, Pask points out in an interview with National Geographic that 13 young tigers taken directly from their mothers’ pouches were preserved in alcohol and this particular one was special:
“This pouch young seems to be a magical specimen that happens to have really good intact DNA.”
The quality of that DNA led to the complete genome sequencing, which led the researchers to compare it to the genomes of animals that resembled the Tasmanian tiger – such as dingoes and dogs – and those that were fellow marsupials like the wallaby and the Tasmanian devil.
What they found was surprising. Scientists have historically considered the thylacine to be close to the dingo because of their strong similarities in body size, head shape and raw meat eating habits, making them an excellent example of “convergent evolution,” where two unrelated species without recent common ancestors nonetheless evolve on parallel paths because of their environments.
However, their genes show that Tasmanian tigers are much closer to marsupials, which means further studies are needed to determine how the control areas surrounding the genes turned them on and off to direct the species’ evolution. If (and most likely when) it occurs, this data will also help scientists in their attempt to clone a thylacine and de-extinct them.
Unfortunately, the genome sequencing also shows some of the traits that weakened the species long before its extinction at the hands of humans. While it was assumed that genetic diversity dropped dramatically when the bridge between Tasmania and the mainland disappeared about 15,000 years ago and isolated the animals, the data now indicates that the decline occurred between 70,000 and 120,000 years ago. That most likely switches the cause from isolation to climate change, which forced the species to modify it diet and adapt to different temperatures. Should cloning of the thylacine happen, the researchers would want the strongest genetic design for the best chance of survival.
Which leads us to the question … should cloning happen? Pask thinks we’re at least ten years away from making a whole functioning genome, but that could happen sooner … given the guilt that many feel about the extinction of the thylacine and the propensity we seem to have to act first and ask questions and deal with the consequences later.
Should cloning of the thylacine happen?