Blackduiker
Well-Known Member
Study shows disease played no part in the extinction of the Tasmanian Tiger:
Humans Alone Wiped Out Tasmanian Tiger, Study Says - Yahoo! News
Humans Alone Wiped Out Tasmanian Tiger, Study Says - Yahoo! News
Humans Alone Brought The Tasmanian Tiger To Extinction
- Thread starter Blackduiker
- Start date
actually the study (or at least as it is reported in that article) does not show that disease wasn't a factor. All it is is a statistical analysis which shows that extinction could have been caused solely by hunting. The two things are not the same.
Also I note a couple of posters in the comments below the article picking up on the article's discrepancy between the thylacine's "jaws [being] so weak they likely couldn't have taken down anything larger than a possum" and "a reduction in the thylacine's prey (kangaroos and wallabies)".
Bad article all round really.
Also I note a couple of posters in the comments below the article picking up on the article's discrepancy between the thylacine's "jaws [being] so weak they likely couldn't have taken down anything larger than a possum" and "a reduction in the thylacine's prey (kangaroos and wallabies)".
Bad article all round really.
Agree it isn't very well put together and doesn't present a strong arguement. The conflicting comments about diet seem to have been drawn from different sources without pointing that out.
It may have had weak jaws but my personal opinion is that its large body size and apparently very fast reactions (see the '1928' film where it is 'playing' with the keeper)) meant it would have been able to deal with anything up to Wallaby size at least. I can't see Forester Kangaroos being on the menu though? Too large/fast?
I sometimes wonder if in some ways it was the ecological near equivalent of the placental Foxes.
Regarding the disease. They could(potentially) sometimes recover. Apparently some captives which contracted it, recovered, only to have another bout a few months later. One survived three bouts and then never showed symptoms again for the rest of its life. Its also believed in the wild there would be less chance of infection/reinfection so that at least some individuals were able to develop immunity but sources vary in their views over this.
Incidentally, the two '1928' films appear to show the same animal as the 1933 Fleay film of the last Thylacine at the Zoo. The same snare mark on the rear right hand leg is evident in all three. As it is now established beyond reasonable doubt that he was captured in 1933, the three films must presumably all be from, or after that date. This is being researched at present. (If you are comparing the films, or stills from them, don't be misled by 'reversal' photos- enclosure door and access door to shelter should correctly be on the left side of photo.)
It may have had weak jaws but my personal opinion is that its large body size and apparently very fast reactions (see the '1928' film where it is 'playing' with the keeper)) meant it would have been able to deal with anything up to Wallaby size at least. I can't see Forester Kangaroos being on the menu though? Too large/fast?
I sometimes wonder if in some ways it was the ecological near equivalent of the placental Foxes.
Regarding the disease. They could(potentially) sometimes recover. Apparently some captives which contracted it, recovered, only to have another bout a few months later. One survived three bouts and then never showed symptoms again for the rest of its life. Its also believed in the wild there would be less chance of infection/reinfection so that at least some individuals were able to develop immunity but sources vary in their views over this.
Incidentally, the two '1928' films appear to show the same animal as the 1933 Fleay film of the last Thylacine at the Zoo. The same snare mark on the rear right hand leg is evident in all three. As it is now established beyond reasonable doubt that he was captured in 1933, the three films must presumably all be from, or after that date. This is being researched at present. (If you are comparing the films, or stills from them, don't be misled by 'reversal' photos- enclosure door and access door to shelter should correctly be on the left side of photo.)
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So thylacines were between 15 and 30ish kgs. I believe this makes them very capable of taking down even a reasonably large roo. Although they are not related and there would be a few differences i have seen a 6 month old dingo pup weighing no more than 15 kgs bring down a sheep weighing around 75.
The 'abstract' of the actual paper:
Summary
1. Population viability analysis (PVA) is widely used to assess the extinction risk of threatened species and to evaluate different management strategies. However, conventional PVA neglects important biotic interactions and therefore can fail to identify important threatening processes.
2. We designed a new PVA approach that includes species interactions explicitly by networking species models within a single ‘metamodel’. We demonstrate the utility of PVA metamodels by employing them to reinterpret the extinction of the carnivorous, marsupial thylacine Thylacinus cynocephalus in Tasmania. In particular, we test the claim that well-documented impacts of European settlement cannot account for this extinction and that an unknown disease must have been an additional and necessary cause.
3. We first constructed a classical, single-species PVA model for thylacines, which was then extended by incorporation within a dynamic predator–herbivore–vegetation metamodel that accounted for the influence of Europeans on the thylacine's prey base. Given obvious parameter uncertainties, we explored both modelling approaches with rigorous sensitivity analyses.
4. Single-species PVA models were unable to recreate the thylacine's extinction unless a high human harvest, small starting population size or low maximum population growth rate was assumed, even if disease effects were included from 1906 to 1909. In contrast, we readily recreated the thylacine's demise using disease-free multi-species metamodels that simulated declines in native prey populations (particularly due to competition with introduced sheep).
5. Dynamic, multi-species metamodels provide a simple, flexible framework for studying current species declines and historical extinctions caused by complex, interacting factors.
Source: No need for disease: testing extinction hypotheses for the thylacine using multi-species metamodels - Prowse - 2013 - Journal of Animal Ecology - Wiley Online Library
Summary
1. Population viability analysis (PVA) is widely used to assess the extinction risk of threatened species and to evaluate different management strategies. However, conventional PVA neglects important biotic interactions and therefore can fail to identify important threatening processes.
2. We designed a new PVA approach that includes species interactions explicitly by networking species models within a single ‘metamodel’. We demonstrate the utility of PVA metamodels by employing them to reinterpret the extinction of the carnivorous, marsupial thylacine Thylacinus cynocephalus in Tasmania. In particular, we test the claim that well-documented impacts of European settlement cannot account for this extinction and that an unknown disease must have been an additional and necessary cause.
3. We first constructed a classical, single-species PVA model for thylacines, which was then extended by incorporation within a dynamic predator–herbivore–vegetation metamodel that accounted for the influence of Europeans on the thylacine's prey base. Given obvious parameter uncertainties, we explored both modelling approaches with rigorous sensitivity analyses.
4. Single-species PVA models were unable to recreate the thylacine's extinction unless a high human harvest, small starting population size or low maximum population growth rate was assumed, even if disease effects were included from 1906 to 1909. In contrast, we readily recreated the thylacine's demise using disease-free multi-species metamodels that simulated declines in native prey populations (particularly due to competition with introduced sheep).
5. Dynamic, multi-species metamodels provide a simple, flexible framework for studying current species declines and historical extinctions caused by complex, interacting factors.
Source: No need for disease: testing extinction hypotheses for the thylacine using multi-species metamodels - Prowse - 2013 - Journal of Animal Ecology - Wiley Online Library
RIP Thylacine... May you forever be an example of Human cruelty
~Thylo
~Thylo
RIP Thylacine... May you forever be an example of Human cruelty
I would describe it more as stupidity/ignorance. Settlers and hunters were not being deliberately 'cruel', they thought, rightly or wrongly, that Thylacines were a pest, a threat to their livestock, or 'vermin' to be destroyed. Though not everyone was of this opinion. Some people kept them as pets- there are suggestions that in some ways they behaved like dogs and were similarly amenable to living with people/domestication- though how correct that is we will never know now.
Findings of DNA'd 1960's Possible Thylacine Scat analysis.
I cannot now find the relevant thread on which it was discussed previously, but I've now read that the results of the DNA analysis of possible Thylacine scats collected by Eric Guiler in the 1960's era proved negative as far as being from Thylacines. It doesn't say what they actually were but its yet another dead end.
I cannot now find the relevant thread on which it was discussed previously, but I've now read that the results of the DNA analysis of possible Thylacine scats collected by Eric Guiler in the 1960's era proved negative as far as being from Thylacines. It doesn't say what they actually were but its yet another dead end.
I cannot now find the relevant thread on which it was discussed previously, but I've now read that the results of the DNA analysis of possible Thylacine scats collected by Eric Guiler in the 1960's era proved negative as far as being from Thylacines. It doesn't say what they actually were but its yet another dead end.
Or possibly a cover-up, not that I'm the conspiracy type.
~Thylo
I cannot now find the relevant thread on which it was discussed previously, but I've now read that the results of the DNA analysis of possible Thylacine scats collected by Eric Guiler in the 1960's era proved negative as far as being from Thylacines. It doesn't say what they actually were but its yet another dead end.
here: http://www.zoochat.com/2/cryptozoology-14782/index17.html
The DNA testing was done in early 2007 and I hadn't been able to find anything on the results, suggesting that they were from some more likely animal. Have you read something more definite (as in that they were negative results)?
Yes I have. They were tested by a Jeremy Austen from University of Adelaide. The findings were apparently annouced 2009/10 that they were not Thylacine, mostly Devil and a few unidentified but not from Thylacines. Sorry, I'm not very good at providing links but found several references to this by typing in Thylacine DNA Scat analysis/Jeremy Austen/,Sydney Morning Herald etc. This was also reported in Tasmania's Mercury newspaper.