The Tasmanian tiger may have been threatened by inbreeding before humans hunted the marsupial into extinction, a new genetic analysis suggests. The last captive tiger died at a Tasmanian zoo in 1936 after a decades-long effort by farmers and hunters to kill the creatures and collect a government bounty, but the new study suggests that the tigers’ lack of genetic diversity left them particularly vulnerable to the human onslaught and outbreaks of disease. “It’s looking like the thylacines were sort of on their last legs,” says Webb Miller [Science News], one of the coauthors.
Researchers sequenced the mitochondrial DNA of two Tasmanian tigers, more properly known as thylacines, from tissue samples preserved at museums in Sweden and the United States. And while the researchers’ main goal was to investigate the roots of the thylacine’s extinction, they acknowledge that having a complete genome at their disposal is sure to prompt talk of cloning. Says Miller: “Our goal is to learn how to prevent endangered species from going extinct…. I want to learn as much as I can about why large mammals become extinct because all my friends are large mammals,” Professor Miller added. “However, I am expecting that publication of this paper also will reinvigorate discussions about possibly bringing the extinct Tasmanian tiger back to life” [BBC News]. Some scientists think that the thylacine would be one of the easiest extinct animals to resurrect, as it died out recently and several well-preserved specimens exist in museums.
As reported in the journal Genome Research, when the researchers compared the two specimens’ genomes they found only five differences in a sequence of 15,492 nucleotides. The researchers note that a distemper-like disease swept through wild and zoo thylacine populations from 1900 to 1910. A lack of genetic diversity could have left the animals susceptible to the disease [Science News]. Then the relentless guns of the hunters may have finished the species off.
While a link between extinction and poor genetic diversity hasn’t been definitely proven, researchers say the new findings have immediate relevance for the battle to save endangered species. In particular, the Tasmanian devil is severely threatened by a facial cancer that has already wiped out about half the population, and early research indicates that the devils have poor genetic diversity as well. Says study coauthor Stephan Schuster: “We’re trying to find the genetic differences between them, only this time around we would like to use this information for pedigree selection…. We will tell the breeding efforts already under way in Australia which animals they have to breed to have the maximum success in stabilising the population, and to breed the most genetic diversity possible” [BBC News].
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Image: Wikimedia Commons
January 13th, 2009 at 2:30 pm
The animal should have been protected when it became endangered and put in a preserve.
January 13th, 2009 at 2:41 pm
why would they bring the tiger back to life?
January 13th, 2009 at 2:45 pm
Best headline yet.
January 13th, 2009 at 2:47 pm
So is there only one more of these tigers left?
January 13th, 2009 at 2:48 pm
how are you going to bring that tiger back to life is my ?Question?
January 13th, 2009 at 2:50 pm
Why want they just leave the animals alone and let them live.I think that they should bring the tiger back to life and quit hunting and killing the animals that don’t do any harm to them or anyone else.
January 13th, 2009 at 2:57 pm
why dont they breed more like that?
January 13th, 2009 at 2:59 pm
I think that they sould have messed with the animals breed because that is not goin to keep the animal alive
January 13th, 2009 at 3:00 pm
Could scientists really bring back a extinct species and expect it to live as long as they did back in the past?
January 13th, 2009 at 3:03 pm
They probably were under pressure from competition from introduced dingos (brought there by traders before Europeans arrived), not to mention habitat depletion from human activities, overhunting of prey, etc. This may have contributed or caused a population crash, reducing genetic diversity, or maybe there were just so few left that only a small closely related subpopulation survived.
January 13th, 2009 at 3:04 pm
I think they should just leave all of that cloning alone and spend there money were it could really be used
January 13th, 2009 at 3:15 pm
most of my friends are large mammals as well. It would be good to know how these extinctions occur. Oh, too clear any confusion, the picture at the top is from before 1936, when the last one, you know, died.
January 13th, 2009 at 3:19 pm
Decade by decade, century by century, millennium by millennium we will extend our cloning technology, to resurrect the past to better study it. Once this technology has gone far enough, and our mores on human cloning have changed (a few hundred years max? Once the christianity and islam realizes this means we can clone saints, oh baby it’s on), we will start mining ancestral DNA, especially of people who died without children, to see if they have anything else they can contribute back to human culture. Imagine finding which segments of DNA are responsible for the brain systems that control musicianship (which is actually most of our brains according to fMRI studies.) and then going and studying Beethoven’s or Smetana’s or Stravinsky’s or Tchaikovsky’s DNA and seeing what their DNA can tell us about their brain systems. The answer could be a shocking “nothing out of the ordinary.” Maybe we can study the DNA of brain systems responsible for imagination in true titans of the mind, like the aforementioned composers or Einstein, Newton, anyone whose remains remain with us.
I think it will turn out that our ancestors set the stage for DNA retention for future generations, without precise knowledge of what they were doing, just knowing that there was something in their ancestors worth trying to keep intact. As it turns out, they’ve provided us with one of the more useful tools for studying ourselves: our past. DNA snapshots backing up the human genome at various points in time, whether by mummification (if anything is recoverable from that) or accidental bog and ice mummies.
Think about this: we can study humans from before, during and after plagues, if DNA is available, and can gain insights into how our immune systems deal with invaders, and use that information to combat the plagues of today.
Re: Chandler brown – they didn’t have much in the way of conservation at the time. The government was paying people to eradicate them, pretty hard to fight that.
Re: Catherine T – we need to start studying higher-order mammal extinction so we can keep an eye out for the same thing happening in the human race, even if we may not be able to do anything about it. It’s inevitable that catastrophe will happen, and the more we know about how that went down in the past the better we’re able to cope with it in the present.
January 13th, 2009 at 4:40 pm
Nick- I like the way you think. if the shroud of Turin was real, what if somebody extracted DNA from that, hence the second coming? Shakespeare has no living descendants. let’s reintroduce that DNA, shall we?
January 13th, 2009 at 9:46 pm
I find this article’s title quite disgusting. Isn’t screwing oneself the purest form of inbreeding?
January 15th, 2009 at 11:22 am
I see that the tasmanian tigers weren’t the only ones inbreeding.
January 15th, 2009 at 12:04 pm
It frightens me, how many species are endangered now. It makes me so sad. Way time to limit our population growth so that earth’s other creatures have a chance to survive. We are the polluters and the killers. The human race is in danger of going extinct, as well. We depend on a healthy environment.
When I look at the picture above, I get angry. How wonderful it would be if this creature, the moa, the dodo, the passenger pigeon, etc, etc, etc, were still here on earth. These creatures did not die out by natural selection, they died out because of human fear, greed, ignorance, and agression.
January 15th, 2009 at 1:34 pm
When I look at the picture above I get hungey. How wonderful it would be if this creature, the moa, the dodo, the passenger pigeon, etc,etc,etc were still able to end up on my dinner plate.
September 18th, 2009 at 10:44 am
I believe that since humans took the life of these animals the least they could do was to bring them back and give them a fighting chance and also the crap about diesease wiping most of them off is pathetic really????? can humans be so cruel and arrogant as to not even want to accept that they are the ones that destroyed these gorgeous and unique animals to the point they have to make excuses?!?!?! REALLY??!?!?!?!! but please this is ridiculus i think that cloneing is a good thing as long as they dont keep the poor animal wrapped up in cages the rest of their exsistence i think that they should be kept after revival bred to make more ammunity and more gene differeces and then let the lots of them back into austrailia where they belong lol well im done ranting laters