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They were effectively killed by the introduction of the dingo a few thousand years ago. Tasmania is too small to support an apex preditor like the Tasmanian tig

They were effectively killed by the introduction of the dingo a few thousand years ago. Tasmania is too small to support an apex preditor like the Tasmanian tiger long term and maintain the needed genetic diversity. This is the same problem faced by the Tasmanian devil and it is why the transmissible cancer has spread.

RVuRnvbM2e 8y ago
Uh, but the Tasmanian Devil is still alive. The Tiger was "effectively" and literally wiped out by European immigrants.
- danieltillett 8y ago
  Umm I think you missed the point of my post. The Tasmanian tiger was found all over Australia until a few thousand years ago. It was the introduction of the Dingo that caused its extinction (this was not by European immigrants by the way). Only the population in Tasmania survived thanks to the rising sea level cutting off Tasmania from the Australian mainland. The population in Tasmania was too small to support the genetic diversity required for a sustainable population - the extinction was just a matter of time due to inbreeding. On this topic while there was some hunting, the cause of the collapse of the Tasmanian tiger population is unknown and there is some thought that it might have been due to disease not hunting. Yes the Tasmanian devil is still alive, but it has almost no genetic diversity. This is why the facial cancer is able to spread from animal to animal. Edit. I should add the Tasmanian devils were also found on the mainland until the dingos wiped them out too.
  - XalvinX 8y ago
    Your "extinct from inbreeding" theory is not likely. There are many examples of animals coming back from groups well under 100, and doing fine. Such as the sea otter of California which was down to somewhere between 25 and 50 and is now over 3000, with no signs of deformities or other problems.
    - danieltillett 8y ago
      Sustained inbreed on a small island is a very common way for apex predators to become extinct and there are lots of examples from around the world of this happening after the last ice age. 100 might be OK for a short drop (~150 is considered the bottom end for most populations), but sustain a population at 50 breeding pairs for a few hundred generations and every allele in the population will end up homozygous though genetic drift.
olliej 8y ago
What? Tasmanian devil population was robust until 1840 when a bounty was introduced because of a mistaken belief that they hunted livestock. The hunting for bounty and outright culling almost made them Extinct. They only became protected after the last thylacine died. Subsequent attempts to unprotect and poison them were by idiot farmer who kept deciding they killed livestock. Anyway, the result of the near extinction caused by humans drastically reduced genetic diversity, which meant even though their numbers did increase they were highly susceptible to any disease, in this case it’s a transmissible disease. Since the 90s their population has dropped by 80%. As far as thylacine goes - you claim it was introduction of dingoes thousands of years ago, and the there is evidence the aborigines has been present in Australia for at least 10000 years. Yet it wasn’t a hundred years of hunting by Europeans that it went extinct. The causation seems much more to be on the head of humans (specifically Europeans, who have a huge documented history of exterminating animals in land that they migrate to - not to say only Europeans cause extinctions, just that the nature of our society means we have much more documentation of European history than of locations that weren’t well, in Europe)
- danieltillett 8y ago
  You have managed to get Tasmanian tigers and Tasmanian devils confused. Tasmanian devils are very much not extinct. The Dingo was a rather late arrival in Australia - around 4000 years ago [1]. This was after Tasmania was separated from the mainland by rising sea water after the end of the last ice age which is why they never reached Tasmania. It is not my claim that Dingos were responsible for the extinction of the Thylacines on the mainland [2] - I just happen to be far more informed about this topic than some posting here. 1. https://en.m.wikipedia.org/wiki/Dingo https://en.m.wikipedia.org/wiki/Dingo 2. https://en.m.wikipedia.org/wiki/Thylacine#Extinction https://en.m.wikipedia.org/wiki/Thylacine#Extinction

RVuRnvbM2e 8y ago

Uh, but the Tasmanian Devil is still alive. The Tiger was "effectively" and literally wiped out by European immigrants.

danieltillett 8y ago
Umm I think you missed the point of my post. The Tasmanian tiger was found all over Australia until a few thousand years ago. It was the introduction of the Dingo that caused its extinction (this was not by European immigrants by the way). Only the population in Tasmania survived thanks to the rising sea level cutting off Tasmania from the Australian mainland. The population in Tasmania was too small to support the genetic diversity required for a sustainable population - the extinction was just a matter of time due to inbreeding. On this topic while there was some hunting, the cause of the collapse of the Tasmanian tiger population is unknown and there is some thought that it might have been due to disease not hunting. Yes the Tasmanian devil is still alive, but it has almost no genetic diversity. This is why the facial cancer is able to spread from animal to animal. Edit. I should add the Tasmanian devils were also found on the mainland until the dingos wiped them out too.
- XalvinX 8y ago
  Your "extinct from inbreeding" theory is not likely. There are many examples of animals coming back from groups well under 100, and doing fine. Such as the sea otter of California which was down to somewhere between 25 and 50 and is now over 3000, with no signs of deformities or other problems.
  - danieltillett 8y ago
    Sustained inbreed on a small island is a very common way for apex predators to become extinct and there are lots of examples from around the world of this happening after the last ice age. 100 might be OK for a short drop (~150 is considered the bottom end for most populations), but sustain a population at 50 breeding pairs for a few hundred generations and every allele in the population will end up homozygous though genetic drift.

olliej 8y ago

What? Tasmanian devil population was robust until 1840 when a bounty was introduced because of a mistaken belief that they hunted livestock. The hunting for bounty and outright culling almost made them Extinct. They only became protected after the last thylacine died. Subsequent attempts to unprotect and poison them were by idiot farmer who kept deciding they killed livestock. Anyway, the result of the near extinction caused by humans drastically reduced genetic diversity, which meant even though their numbers did increase they were highly susceptible to any disease, in this case it’s a transmissible disease. Since the 90s their population has dropped by 80%. As far as thylacine goes - you claim it was introduction of dingoes thousands of years ago, and the there is evidence the aborigines has been present in Australia for at least 10000 years. Yet it wasn’t a hundred years of hunting by Europeans that it went extinct. The causation seems much more to be on the head of humans (specifically Europeans, who have a huge documented history of exterminating animals in land that they migrate to - not to say only Europeans cause extinctions, just that the nature of our society means we have much more documentation of European history than of locations that weren’t well, in Europe)

danieltillett 8y ago
You have managed to get Tasmanian tigers and Tasmanian devils confused. Tasmanian devils are very much not extinct. The Dingo was a rather late arrival in Australia - around 4000 years ago [1]. This was after Tasmania was separated from the mainland by rising sea water after the end of the last ice age which is why they never reached Tasmania. It is not my claim that Dingos were responsible for the extinction of the Thylacines on the mainland [2] - I just happen to be far more informed about this topic than some posting here. 1. https://en.m.wikipedia.org/wiki/Dingo https://en.m.wikipedia.org/wiki/Dingo 2. https://en.m.wikipedia.org/wiki/Thylacine#Extinction https://en.m.wikipedia.org/wiki/Thylacine#Extinction