By Hanna Lichtenstein, Katy Lawler, Emily Ronis, and Joelle Bailey
They exist today only in paintings, black and white photographs, and degraded specimens collected years ago as a distant memory of wild Tasmania. But soon the thylacine, or Tasmanian tiger, may be coming back to life. Geneticists and conservationists are coming together to give extinct species a second chance. De-extinction was once purely science fiction, but it becomes more real every day. By reconstructing the genome of extinct species from preserved specimens, DNA can be spliced with a similar species and implanted into a surrogate, potentially leading to the birth of an animal thought to be lost forever.
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| The last thylacine, photographed in 1933 |
The limited information we have on wild thylacines sheds some light on their biology, and some implications for their reintroduction.There is evidence from skull structures that the thylacine could only take on small prey, such as wallabies, wombats, and possums. The thylacine favored ambush techniques and hunted in family groups. Their primary habitat included coastal shrublands and woodlands, finding caves or vegetation to hide and sleep in during the day. For thousands of years thylacines could be found on the Australian mainland, evidenced only by fossils and cave paintings. They died out well before European settlers reached Australia, probably due to competition with dingoes. Although unrelated species, the thylacine and the dingo were superficially very similar, due to a process known as convergent evolution, in which two species evolve to fit the same ecological niche.
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| A thylacine next to a dingo, showing similar morphology |
In order to accomplish this goal of de-extinction, a surrogate species is necessary. This species needs to be an extant animal closely related to the thylacine, and one that could provide the DNA template for the splicing of thylacine genes. In this case, the numbat seems to be the most highly qualified surrogate for thylacine de-extinction. The numbat (Myrmecobius fasciatus) is one of the thylacine’s closest relatives, although it differs from it greatly. More similar in appearance to an anteater, the numbat is diurnal and feeds exclusively on termites. They are found on the Australian mainland where they live in arid woodland environments and sleep in hollow logs to avoid predation. Unusually, the numbat does not have a pouch. However, like other marsupials, the numbat gives birth to extremely premature young, making it compatible with the thylacine despite considerable differences in size.
Should surrogacy in numbats be successful, thylacines could once again roam free in Tasmania. But this resurrection is not without obstacles. The thylacine population declined in part due to a distemper-like disease. Since their extinction, distemper has been an increasingly common problem in wild and domestic canine populations around the world, including Australia and New Zealand. If we were to reintroduce thylacines, there is a risk that they could be affected by distemper or a similar virus. The animals could potentially be treated with a vaccine, but this would require the animals to be captured on a regular basis for it to be applied.
Another threat to the reintroduction is the changed environment of Tasmania today compared to the historical wilderness. The environment that the thylacines once lived in has been altered greatly with time and anthropogenic development, especially increased logging activity. There will be less land, fewer sources of food and water, and less cover to hide in. However, the extensive national parks and wildlife preserves in Tasmania would provide a habitat where the thylacine could remain undisturbed by humans, and be in a protected and healthy ecosystem. The animals would be far away from people’s livestock and pets, where problems from predation could arise again.
Even under the most ideal of circumstances, there will be high levels of stress placed on the animals. The capturing and recapturing of the thylacines as well as the new environment could cause a strain on the population, ultimately leading to other problems. High levels of stress can lower immune response and can lead to decreased fertility. There is, however, one known case of a pair of thylacines successfully breeding in captivity. This occurred in the early 20th century when zoo conditions were extremely poor. Hopefully, this can be taken as an indication that the thylacine adapts well and will be able to reproduce and flourish if placed in the correct environment. However, the reintroduced populations would have to be monitored closely through periodic tests of stress hormone levels.
A viable reintroduction of the Tasmanian tiger would need proper management, as well as proper timing. To ensure the best chance of natural reproduction in the wild, the thylacines could be released into the parks and reserves in the summer months. This would allow them to adjust and establish a home range without the pressures of winter weather and before peak breeding season in the spring. Managers would hope to have enough thylacines in the population to prevent inbreeding, as well as to create a base or buffer against any impacts that disease or other pressures could have on the population. Historic numbers are unclear, but populations usually require several hundreds of individuals to survive. Close and constant monitoring would be required to ensure that the thylacines are adapting well and staying healthy, indicated by stress hormones and successful reproduction, and are staying within the park boundaries to reduce human-tiger conflict. Since thylacines aren't particularly territorial, management wouldn't have to fear movement outside of the intended habitat ranges once the species settles into the new area. Thylacine numbers should be monitored with caution to make sure the newly re-introduced animals are not invasive, and that the population numbers remain stable.
While the de-extinction of thylacines has its obstacles, science is getting closer every day to making living Tasmanian tigers a reality. Not only will they persist in photographs and paintings, but they could soon be roaming and exploring the wilds of Tasmania that their ancestors once called home.
Further Reading:
Extensive information on the thylacine.
Tedx talk focused on de-extinction in both gastric brooding frogs and the thylacine
Link for information on the numbat.
Link for numbat reproduction.
Power, Vicki, Cathy Lambert, and Phillip Matson. "Reproduction Of The Numbat (Myrmecobius Fasciatus): Observations From A Captive Breeding Program." Australian Mammalogy 31.1 (2009): 25-30. Wildlife & Ecology Studies Worldwide. Web. 7 May 2013.
Barbara A. Wilson, et al. "If The Tasmanian Tiger Were Found, What Should We Do? An Interdisciplinary Guide To Endangered Species Recovery." Endangered Species Update 19.4 (2002): 194-200. Wildlife & Ecology Studies Worldwide. Web. 8 May 201
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Dingos, Devils & Thylacines, Oh My!By Morgan Martin, McKinzie Fink, Madeline Leonard, Natalee Yates
Charles Darwin once said, “Nevertheless so profound is our ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of the forms of life!” Imagine if scientist could undo our mistakes and bring back species that have been destroyed from our world. Currently, scientists believe this is possible and plan to bring creatures like the thylacine back to life.
The thylacine or Tasmanian tiger is one of the 20th century’s most recognized extinct species. This large carnivorous marsupial once roamed all over Australia. In recent times it was limited to Tasmania, ranging from the north and east coast and midland plains. Now this remarkable creature is gone from our world, never to be seen again. Although it is unknown exactly how the thylacine became extinct from the mainland, some believe that hunting and competition with the dingo may have been the cause. Its extinction in Tasmania was mainly caused by farmers that believed them to be attacking their sheep. From 1888 to 1909, the Tasmanian Government paid a bounty for 2,184 thylacine skins, although it is believe more were killed. Other issues like habitat loss, disease and competition with feral dogs also abetted in the extinction of this species. Even though, many efforts were plotted to save the thylacine none were successful. Sadly, on September 7, 1936, the last living Tasmanian tiger, named Benjamin, died at Hobart Zoo in Tasmania because of neglect, depression, and harsh weather conditions.
To begin to process of reviving the thylacine, we must first understand its biology. It was the largest carnivorous marsupial in the world, and could be distinguished from canines by its striped back and hindquarters, wide gaping jaws, low to the ground tarsus on the hind legs, and presence of a backwards-facing pouch in both sexes. General lifespan was from five to seven years. Their habitats consisted of dry eucalyptus forests, wetlands, and grasslands.
Thylacines were nocturnal and pursuit predators, and would often chase down fast prey and catch them with their gaping jaws. They’re jaws were weak but long, allowing them to catch faster and smaller prey animals like kangaroos, wombats, wallabies, bandicoots, rodents, lizards and birds They were typically solitary, but breeding couples were often seen hunting together. Their main competitor was the Tasmanian devil.
Little is known about thylacine reproduction. It is believed that the breeding season occurred once a year and that pups stayed in their mother’s pouch for about nine months. Females were known to carry at least two pups per litter, though it is indefinite how many litters are birthed prior to any mortality.
The next step in de-extinction would be establishing a surrogate species to carry a cloned thylacine to term since it cannot be incubated in a test tube. The surrogate must be a close relative, within the thylacine’s phylogeny in order for the fetus to develop properly. The current closest living relative to the Tasmanian tiger is the Tasmanian devil, and must be used as a surrogate.
The devil is the top carnivorous marsupial endemic to Tasmania. They are nocturnal hunters and scavengers that can consume every bit of their catch with their powerful teeth and jaws. They are generalists and will eat almost anything they can catch or find. They are solitary hunters, but gather in groups to feed on carcasses.
Mother devils give birth to about twenty to thirty young. As soon they are born the pups must fight for access to their mother’s four pouch nipples, so only a handful of infants survive. Females carry their young in their pouches for about four months.
However, this species is currently being threatened by an illness called devil facial tumor disease, it has inflicted the Tasmanian devil population since the 1990s. It is a rapidly spreading contagious cancer that causes large lumps to form around the face, making it hard to eat and see. The animals ultimately starve to death. DFTD is spread by close contact and bites from other infected individuals. Due to the fatalities from the disease, the Tasmanian devil is listed presently listed as a vulnerable species, and could have implications on using them as surrogates for thylacine revival.
The ability to revive an extinct species is an incredible innovation that opens many doors for biologists and wildlife scientists alike. Regardless, the inevitable complications that will arise with de-extinction must be considered before we proceed to reintroduce Thylacines to the living world. One of the most immediate concerns should be why the Thylacine went extinct in the first place. Though there were many factors that lead to this species annihilation, an important one would have to be the loss of its habitat. Europeans began colonizing in Australia in the late 1700’s, establishing homes, streets and other urban accessories in place of natural habitats. The amount of people and buildings in Austalia has certainly not decreased at all since the extinction of the Thylacine, so can we provide a niche for this species or do we risk it dying off again because it still has no where to thrive?
The threat of disease must also be considered. Recall the Tasmanian devil, the surrogate species to the Thylacine, its populations are being hugely damaged by the highly contagious facial tumor disease. Would a de-extinct Thylacine be at greater risk of infection because its closest relative is the carrier? There are many other disease related threats that arise with civilization being near this species’ habitat, such as rabies or canine distemper which a domestic dog could pass on to a Thylacine.
Another precursor to Thylacine de-extinction is establishing how its reintroduction will be managed, monitored and studied. These preparations will not just involve officers of wildlife management, if we want the thylacine to make a successful comeback we must first get the general public on board. How should this be done? First off, bringing an animal back from extinction is just plain cool, and by promoting the spectacle of this scientific innovation alone we could get the public excited about the idea. We could produce cute commercials that would teach the public about thylacines while appealing to their empathetic side, so they would be more compassionate about the idea of reviving the species. Facts like how the Thylacine could reduce the invasive rabbit population and lacks the ability to kill sheep should also be emphasized, so it will be better understood that this animal can help the community rather than harming it. We would also put some of the first thylacines in zoos to raise public interest.
Additional Resources:
An article suggesting the cause of Thylacine extinction from the mainland of Australia was relative to the introduction of a Dingo species from Asia
Skull mechanics and implications for feeding behavior in a large marsupial carnivore guild: the thylacine, Tasmanian devil and spotted-tailed quoll
Interesting article simulating the feeding behavior of the Thylacine using the Dingo as a model:
Live Footage of Thylacines in Captivity.
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De-Extinction: Dawn of the Dead Down Under
By Alexander Pelletier, Shawne Felts, Patrick Roden-Reynolds, and Sally Dry
A zombie apocalypse is upon us, but don't fret. There won't be any possessed, flesh eating humans terrorizing your local town. Instead, scientists have the chance to bring back an animal from extinction. A museum in Tasmania is in possession of an immature thylacine, commonly known as the Tasmanian tiger, preserved in alcohol. Alcohol is less destructive to the DNA during the preserving process; meaning scientists are able to extract high quality fragments of DNA from the 147 year old specimen. This makes the thylacine a viable subject for cloning. Not only does the thylacine harbor biological importance, but cultural importance too. The thylacine is an icon, stamped on license plates, popular sports teams, and the face of Australia's #1 selling beer.
An adult thylacine stretches from 1-1.3 meters long and stands 60 cm tall at the shoulder with an average weight between 15-30 kilograms. The thylacine is a perfect example of convergent evolution. Closely related to opossums and kangaroos, the demands of its predatory lifestyle molded it into a wolf-like hunter. It is crepuscular in habit and mainly shy. The thylacine pursues its prey tirelessly over long distances with its strong sense of smell. It resides in mixed mosaic woodlands, dry Eucalyptus forests, and open grasslands. They are known to hunt both solitarily and as a family unit. Observations suggest the thylacine formed male/female pair bonds at breeding age which is 3 years for females and 2 years for males. Because the thylacine is a marsupial, the female rears about 4 young in its pouch and cares for them up to 9 months.
A surrogate species is a particular species used to complete the genetic code for cloning. In this case, the Tasmanian devil is a fitting surrogate to the thylacine because it is a keystone predator and a marsupial as well. It is known that Tasmanian devils are opportunistic hunters, able to pant and shiver, and enter daily torpor, which is shallow hibernation. Devils can eat up to 15% of their body weight in a day, and if the opportunity arises they can eat 40% of their weight in little as 30 minutes. This causes them to become lethargic after large meals. Because the Tasmanian devil is the closest living model we have to that of a thylacine, it is possible to format a possible restoration plan for the thylacine based off of the current restoration plan for the Devils enacted by Australia’s Department of Primary Industries, Parks, Water, and Environment.
It is impossible to bring back a species from extinction without encountering several key problems. One of the most important problems facing reintroduction of the thylacine is that they primarily lived in locations now inhabited by people. These coastal regions of Australia and Tasmania are experiencing rapid human population growth, therefore limiting the amount of suitable coastal habitat. To avoid a similar conflict with the native people of Australia and Tasmania, the opinions of the public must be considered before any action is taken. It is imperative to educate the locals about the reasons and both positive and negative consequences about the reintroduction of the thylacine. Another concern is introducing an apex predator, which influences the top-down trophic cascade. In other words, the introduction of a top predator could alter the population numbers of every prey species below it on the food chain. As an example, check out what happens when another top predator, the wolf, is introduced into an ecosystem in which it was extirpated. Specifically, the thylacine may outcompete the native Tasmanian devils, which are top predators that are already endangered. The thylacine may dominate the food chain, leading Tasmanian devils to fall further towards extinction. Is it worth bringing back a species from extinction to potentially cause another species to disappear?
Taking all of the obstacles the reintroduction poses into account, certain steps should be taken to ensure the most successful restoration plan. Reintroduction is a slow process; a formerly extinct species can not be thrown back into the wild quickly or in large numbers and be expected to survive. The plan is to release 3-4 family units of about 6 individuals each into parks or other federally managed land and preferably near the coast. This will minimize human interactions with thylacine. Each family unit will be moved into a temporary caged enclosure for about 6 weeks to acclimatize before release into the wild. Heavy monitoring should be taken in the early stages of reintroduction to ensure success in the long term. Microchips would be implanted beneath the skin for monitoring purposes. In this way, researchers can continue to collect data on their movements, health, and interactions with surrounding wildlife. One of the biggest concerns would be monitoring the possible transmission of Tasmanian Devil Facial Tumor Disease, which has played a large role in decreasing devil numbers.
Still interested? Follow these URL’s to learn more about issues related to the possible de-extinction of the Thylacine: Thylacine History, Tasmanian Devil Facial Tumor Disease, Online Thylacine Museum, Miscellaneous Natural History Information
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Inside the Pouch of the Tasmanian Tiger
By Caitlin Greene, Eleonore Conis, Casey Maynard, and Cody Wendelin
Imagine yourself on a safari in southern Australia. You’re traveling in a jeep with a tour guide, showing you all of your favorite members of Australian wildlife, like kangaroos, koalas, and more! Suddenly, out of the corner of your eye, something makes a bush shake violently. As you turn your head to see what it was, a short creature with stripes on its back and a long tail dashes across an opening and disappears quickly into a bush with a bloody meal. Your tour guide has no clue what sort of animal it could’ve been, except for one, but it’s extinct. There have been many supposed sightings of this creature, as seen on the Today Show in Australia, which most people believe to be the Thylacine, also known as the Tasmanian tiger.
Native to the island of Tasmania, Australia, and New Guinea, the Thylacine roamed the woodlands and plains freely over 200 years ago. This elusive creature was 6 feet in length, from nose to tip of tail, and 2 feet tall, from feet to shoulders. They have a long, pointed snout, like that of a wolf, and stripes going across its back, from neck to tail. Back in the later 1880’s, farmers despised this “dangerous” creature so much that there was a massive bounty out for the hides of the Thylacines, which led to their eventual extinction. A farmer shot the last wild Thylacine in 1930, and the species was officially declared extinct in 1986.
Now you may be asking yourself, how are we supposed to bring back this extinct creature? The answer to that is not so simple, but we’ve come up with a solution: Tasmanian Devils. The Thylacine shared not only the inhospitable land of the Aussies with the Tasmanian Devils, but many more behaviors and characteristics. We can assume they were already well integrated because the Thylacine had a broad range of habitat that stretched onto the island of Tasmania. These animals are both considered apex predators, they are at the top of the food chain. Using these similarities and more, we’ve decided that the Tasmanian Devil would make a pretty good surrogate mother for a Thylacine fetus (a surrogate is basically a replacement). How did we come up with that? Research of course!
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| G’day mate! |
If we reintroduce Thylacines, but they can’t handle their new ecosystem, we will have failed again. 3 main obstacles exist to their survival: new diseases, habitat change, and predators.
A variety of new diseases have come into existence since the Thylacine was alive. A new form of distemper has been introduced in Australia, mainly in Tasmanian Devils, which are closely related to the Thylacine. One way to combat this is to vaccinate each batch of Thylacines as we integrate them into the community. Vaccines are available, for the majority, of the distemper for the Tasmanian Devils, so we could potentially modify it to meet the Thylacine’s needs. Rabies is also a potential threat. As long as the Thylacine doesn’t come into contact with a carrier, we should be able to bypass this.
Australia has had incredible growth along the coasts, which has led to habitat destruction for the Thylacines. Specifically, urban growth has significantly increased since the 1900’s. Coastal areas provide the best temperature range suited for their physiology, so this poses a problem. . One possible solution is to integrate these guys into Australia’s parks. The parks are government regulated, so human contact wouldn’t be as much of an issue - fences and regulations restrict how much traffic comes in and out.
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| Population density in Australia |
Although Thylacines are an apex predator, dingos could potentially pose a threat. Competition between the two species would be relevant to the survival of the newly introduced species. Thylacines mainly eat wallabies and other small animals. Dingos have been known to take their fills on the same type of animals. An easy way to eradicate this problem is to regulate the number of prey let into the national parks. We could also use trap and release measures for the dingo population within the parks.
This video shows the techniques the dingo uses for hunting. The Thylacine would use similar tactics. If you want to read more, you may go to http://www.naturalworlds.org/thylacine/index.htm.
Reintroducing the Thylacine would be quite challenging due to the number of obstacles it would face. In order to give them the best possible chance at establishing a population we suggest releasing them in coastal national reserves in the Northwestern part of Australia in small numbers (6-12, 1:1 male to female ratio) when available. It is the hope that being restricted to the national reserves people will have limited conflict with them and they will be easier to regulate and protect. Population size should be monitored and managed at a level that can sufficiently compete with local top predators but not have a detrimental or damaging effect on any one specific species.
We recommend that the Australian government should conduct population studies to monitor the Thylacines via radio collars or microchips that allow researchers to study the animals. Vaccinations could be administered before release into the wild as well as the implementation of some protective legislation to increase their protection. In the future, once populations are stable, any nuisance animals can be captured and released back into a reserve or incorporated into a captive breeding program, repetitive nuisance Thylacines can be euthanized.
Educating the public in this endeavor is essential to increase support for this project and will increase the chances of the Thylacine’s survival. Public awareness meetings, videos of the Tasmanian tiger, outreach programs, brochures, and stuffed animals (for the kiddies) are highly suggested in order to spread mindfulness of these special creatures. Another way to increase the Tasmanian tiger’s protection from people and facilitate long term support is encourage possible incentives for people to report poaching of these animals, financial funding for the project reserves through reserve entrance/parking fees, education, and thylacines in zoos to encourage community support. With all of this, the Thylacine can live a sustainable life in this new age.
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Thylacines Deserve A Second Chance
By Samantha Cubbage, Duane Hartwick, Cody Hash, Eileen Long
In the last 7 years, 121 more species of plants and animals have gone extinct in the world, most through human actions. Now, think what could happen if we could bring some of them back. One of these fairly recent extinctions is the Thylacine or Tasmanian Tiger. This marsupial mammal was a native of Australia that, through competition with the introduced dingo and over-hunting by European settlers, rapidly declined until the last one died in captivity in 1936 at the Beaumaris Zoo. It has now been almost 80 years since the Thylacine last walked on Earth, and many things have changed in its old hunting grounds. Much of its native range has been repurposed into commercial housing and urban habitat, dingoes have become even more of a problem throughout Australia, and the Tasmanian Devil, a fairly close relative, has developed a form of aggressive cancer called Devil Facial Tumor Disease (or DFTD).
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| The Thylacine had stripes that went from the shoulder to the base of the tail, making it known as the Tasmanian Tiger. |
Since the extinction of the Thylacine, a disease has emerged that is affecting a closely related species of Tasmanian devils. This disease is known as DFTD (Devil Facial Tumor Disease). It was discovered in the late 1990’s, and is very aggressive and contagious form of cancer that spreads through contact. It is currently the major cause of the dramatic decline in the Tasmanian Devil population. The time from when individuals become infected till death is between 12-18 months. It is currently unknown if the Thylacine would be affected by the disease because they were never exposed to it, though there is note of a possible distemper-like illness at one point. Thylacines will come in close contact with Tasmanian Devils, and they are likely to be exposed to the disease. Since it is impossible to predict how Thylacines will react to DFTD, it could be quite detrimental in the effort restore them. In reality, we may be reintroducing a species only to see disease cause it’s second extinction.
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| DFTD has been detrimental to the Tasmanian Devil (Sarcophilus harrisii) population. Spreading through contact, the cancer eliminates the animals ability to eat. |
Although its original extinction was caused in part by human interference and over harvesting, the reintroduction of the Thylacines would be hampered by the changes to the environment that have happened in the last 80 years. Because of their extinction, they have not faced the climate or environmental changes nor have they developed any form of immunity to the local illnesses. This alone could potentially prevent their successful reintroduction even though bringing back extinct species may cause a positive economic influx through tourism. So even if we managed to reintroduce it successfully in an enclosed habitat, preventing disease and competition between the species that helped cause the original extinction would be almost impossible in its natural environment that has changed so much over the period of time that Thylacine has been extinct.
Further reading:
The Thylacine Project by Don Colgan and Mike Archer (This article can also be found in Australasian Science vol. 21.1 2000)
Could Direct Killing by Larger Dingoes Have Caused the Extinction of the Thylacine from Mainland Australia?
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