TASMANIAN TIGER RESURRECTION

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Context: Scientists in the US and Australia have embarked on a $15-million project to resurrect the thylacine or Tasmanian Tiger, a marsupial that went extinct in the 1930s, using gene-editing technology.

About:

• Tasmanian Tiger (Thylacinus cynocephalus), the only animal in the Thylacinidae family to survive in modern times, was a marsupial mammal that raises young ones in a pouch.
• Even though the species earned its nickname Tasmanian Tiger because of the stripes along its back, it was a slow-paced carnivorous that usually hunted alone or in pairs at night.
• The sharply clawed animal had a dog-like head and ate kangaroos, other marsupials, small rodents, and birds.
• Once widespread in the grass and woodlands of continental Australia extending north to New Guinea and south to Tasmania, the animal’s fate changed after the European Colonisation of Australia.
• The animals were reported to have eaten poultry of farmers, and were killed following official authorisation.
• Apart from this, competition with another animal, the Dingo, is also considered a reason for its extinction.
• The animal was at the top of the food chain, and hence played a significant role in balancing the ecosystem of its habitat by removing the weak animals and maintaining species diversity.
• Also known as the apex predator for the same reason, its disappearance from the food chain resulted in Trophic Downgrading — causal degradation of an ecosystem that occurs when higher trophic level animals are removed from the food chain, resulting in loss or exponential growth of other species.
• Trophic Downgrading also results in disruption of biogeochemical cycles, wildfires, growth of invasive species, and carbon sequestration, among other effects.
• As the thylacine was the only apex predator in its ecosystem, its absence impacted the Tasmanian Devil, which was almost wiped out by a facial tumour disease. The thylacine would have prevented this by removing sick and weak animals from the ecosystem, which would have eventually controlled the spread of the transmissible diseases.

The resurrection process:

• Even though the last living thylacine died over 86 years ago, many embryos and young specimens of the species have been preserved.
• For the de-extinction project, the scientists will be using a genome sequenced from a DNA extracted from a 108-year-old specimen held at Australia’s Victoria Museum.
• This genome will be compared with the closest living animal of the species– the fat tailed dunnart — to identify all the differences. Once all the differences are identified, scientists will engineer the living cell’s DNA where it is different, essentially engineering the extinct species back.
• The fat-tailed dunnart is a mouse-like species in the Dasyuridae family in Australia. With an average body length of 2.4–3.5 inches, they are one of the smallest carnivorous marsupials.
• De-extinction will not be complete until the success of the rewilding process – reintroducing the animal to its native habitat — which will ‘stabilise the fragile ecosystem of Tasmania.’

De-extinction technology: possibilities and challenges

• De-extinction, or resurrection biology, is the method of creating a species that went extinct or is endangered, in order to revitalise ecological diversity and balance shattered due to reasons ranging from biodiversity loss to climate change.
• While cloning is the most widely used method of de-extinction, genome editing and selective breeding are also considered effective ways.
• The Pyrenean ibex, a subspecies of Spanish ibex, was one of the first extinct animals that have been resurrected using somatic cell nuclear transfer (SCNT), even though the baby Ibex died minutes after its birth from lung defect.
• Apart from Colossal’s project to resuscitate Woolly Mammoths and thylacines, a cooperation between the Dutch Foundation partnered with multiple universities, called Tauros Programme, is currently working to breed a cattle species similar to the extinct wild ancestor of domestic cattle, aurochs.
• Other candidates for de-extinction are Maclear’s rat, an extinct large rat species endemic to Christmas Island in the Indian Ocean, the passenger pigeon, a type of migratory bird in North America, and the quagga, which is a subspecies of plains zebra.
• One of the challenges of de-extinction is that reintroducing the species to its former habitat may make it an invasive species, which will also impact the balance of the current ecological system.

https://indianexpress.com/article/explained/explained-sci-tech/tasmanian-tiger-de-extinction-project-explained-8098355/