Tiger’s Extinction Details
This development was announced recently in the publication Nature Ecology & Evolution. This genome has uncovered details regarding this marsupial’s evolution along with its eventual decline toward extinction. These are all vital steps in the plans to clone the tiger and hopefully bring this species back to life from the dead.
Tasmanian tigers, or thylacines, were wolf-sized carnivorous marsupials that were once dwelled in Australia. They became extinct about 3000 years ago on the Australian mainland; however they continued to survive on the island of Tasmania. There it became extinct early in the 20th century as human hunters claimed to be protecting their livestock.
The very last thylacine died at the Hobart Zoo in the year 1936, but it is believed that the species could have survived into the 1940s in the wild. Finally, the animal was declared officially extinct in the 1982.
Data to Collect from the Genome
Scientists desired a more thorough look at these thylacine genes to better understand why these predatory animals became more like wolves during their evolution. Actually, the last time that these two species have shared a common ancestor was some 160 million years ago. However, they have independently lived lifestyles that were very similar and have done so in totally different regions of the world.
“The thylacine and the dog [or wolf] is the closest example of convergent evolution that we’ve ever seen measured between any two species,” claims the lead author Andrew Pask, who is from the University of Melbourne. Since researchers already possess some very robust genomes obtained from dogs and other species that are related, being able to sequence the genome of this extinct animal would be a huge help in seeking out convergent similarities among their genes – this would help them comprehend their evolution from a molecular level.
“If two animals adapt to look almost identical, do you see that also reflected in their genome – can you actually find parts of their DNA that evolve to look very similar?” he added.
“Magical Specimen”
In the year 2008, Pask’s research team was among the first to collect the genetic substance of an extinct species and then have it function within a living species – through the insertion of thylacine DNA pertaining to cartilage and development into living mouse embryos.
In this instance, these DNA sequences have been highly degraded, making it almost impossible to sequence an entire genome. There are around 750 thylacine specimens presently held in museums, and most of these exist in bones or pelts had contain little DNA that is viable. But, there were 13 young specimens that had been removed from the pouches of their mothers and then preserved within ethanol, and as it turned out, one of these babies had amazingly well-preserved DNA.
“This pouch young seems to be a magical specimen that happens to have really good intact DNA,” Pask stated.
Comparing the finished genome to one from dogs, the team found that the two animals did not, in fact, independently evolve similarities in their genes, despite their oddly similar looks and behaviors. Pask says there may be similarities in when genes are turned on and off during development, which will be explored in a future project.
However, these scientists have made a novel discovery: Genetic diversity among thylacines overall have sharply declined between 70,000 to 120,000 years ago. That was not expected at all since scientists have previously thought these diversities declined more recently than this.
“We always assumed that the thylacine, like the Tasmanian devil, had got really restricted genetic diversity once isolated on Tasmania, and that was only 10,000 to 15,000 years ago, when a land bridge to the mainland closed over,” Pask noted.
Resurrecting This Tiger?
Pask admits that it would be great to bring this departed thylacine back to life, “making a whole functional genome, as opposed to having a sequenced genome, are two very different things, so that’s a big hurdle to get across.” He is extremely hopeful that in the near future to be able to obtain a related marsupial, find out all their genome differences, and then edit these differences for the recreation of a new thylacine.
“It would be at least a decade before we have the technologies to really start to pursue de-extinction,” he speculated. “But you never know how fast some of these technologies will develop.”
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