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201302Feb11:51

Tas­man­ian tiger’s extinc­tion caused by humans

Infor­ma­tion
pub­lished 02 Feb­ru­ary 2013 | mod­i­fied 02 Feb­ru­ary 2013
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Thylacine baggedHumans alone were respon­si­ble for the demise of Australia’s iconic extinct native preda­tor, the Tas­man­ian Tiger or thy­lacine, a new study led by the Uni­ver­sity of Ade­laide and pub­lished online on Jan­u­ary 24 in the Jour­nal of Ani­mal Ecol­ogy has con­cluded.

Using a new pop­u­la­tion mod­el­ling approach, the study ‘No need for dis­ease: test­ing extinc­tion hypothe­ses for the thy­lacine using multi-​species meta­mod­els’ con­tra­dicts the wide­spread belief that dis­ease must have been a fac­tor in the thylacine’s extinc­tion.

The thy­lacine was a unique mar­su­pial car­ni­vore found through­out most of Tas­ma­nia before Euro­pean set­tle­ment in 1803. Between 1886 and 1909, the Tas­man­ian gov­ern­ment encour­aged peo­ple to hunt thy­lacines and paid boun­ties on over 2000 thy­lacine car­casses. Only a hand­ful of ani­mals were located after the bounty was lifted and the last known thy­lacine was cap­tured from the wild in 1933.

We found we could sim­u­late the thy­lacine extinc­tion, includ­ing the observed rapid pop­u­la­tion crash after 1905, with­out the need to invoke a mys­tery disease.
Thomas Prowse, project leader, Uni­ver­sity of Ade­laide, School of Earth and Envi­ron­men­tal Sci­ences and the Envi­ron­ment Insti­tute »


“Many peo­ple, how­ever, believe that bounty hunt­ing alone could not have dri­ven the thy­lacine extinct and there­fore claim that an unknown dis­ease epi­demic must have been respon­si­ble,” Dr Prowse says.

“We tested this claim by devel­op­ing a ‘meta­model’ — a net­work of linked species mod­els — that eval­u­ated whether the com­bined impacts of Euro­peans could have exter­mi­nated the thy­lacine, with­out any dis­ease.”

The math­e­mat­i­cal mod­els used by con­ser­va­tion biol­o­gists to sim­u­late the fate of threat­ened species under dif­fer­ent man­age­ment strate­gies (called pop­u­la­tion via­bil­ity analy­sis or PVA) tra­di­tion­ally neglect impor­tant inter­ac­tions between species. The researchers designed a new approach to PVA that included species inter­ac­tions.

“The new model sim­u­lated the directs effects of bounty hunt­ing and habi­tat loss and, impor­tantly, also con­sid­ered the indi­rect effects of a reduc­tion in the thylacine’s prey (kan­ga­roos and wal­la­bies) due to human har­vest­ing and com­pe­ti­tion from mil­lions of intro­duced sheep,” Dr Prowse says.

“We showed that the neg­a­tive impacts of Euro­pean set­tle­ment were pow­er­ful enough that, even with­out any dis­ease epi­demic, the species couldn’t escape extinc­tion.”


(Source: The Uni­ver­sity of Ade­laide media release, 31.01.2013)
UN Biodiversity decade

Goal: 7000 tigers in the wild

Tiger range countries map

Tiger map” (CC BY 2.5) by Sander­son et al., 2006.

about zoos and their mis­sion regard­ing breed­ing endan­gered species, nature con­ser­va­tion, bio­di­ver­sity and edu­ca­tion, which of course relates to the evo­lu­tion of species.
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