Duh and not-so-duh
Jan. 14th, 2009 04:53 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
jaunthieThere have been several articles recently on the ongoing research into the genetics of the Tasmanian tiger. Scientists have been hard at work trying to extract DNA from the preserved remains of these animals, leading to much speculation about whether it would be viable to try and recreate them as a species, among other things. Between the various scientific research teams, they've got a significant chunk of the DNA mapped. I've been following these articles with half an eye, curious about such efforts (there's also an ongoing effort around wooly mammoth DNA) and enjoying the sci-fi/futurist discussions they provoke.
Just a few days ago, a journal article came out about a multinational effort to extract and map the mitochondrial DNA of the Tasmanian tigers based on two different samples preserved on two different continents. The immediate reporting around the findings concentrated heavily on how nearly identical the two samples were, and one article in particular emphasized how surprising that was.
To which I immediately said to myself, well, duh! This seemed perfectly obvious to me (and I have to admit the "and the samples came from continents apart!" comment in the article made me really roll my eyes, because while the samples might now exist continents apart, both animals came from the island of Tasmania at the end of the 19th century). I didn't find it at all surprising that the species would have had very low genetic diversity. It was an island species that had isolated off from a continent-isolated species forebear. Tasmania's arguably most famous animal, the Tasmanian devil, is a very isolated species with extremely low genetic diversity. I would have been surprised if there *had* been a great span of genetic diversity between the two Tasmanian tiger samples.
So, duh.
What was not-so-duh and in fact quite thought-provoking were quotes from some of the scientists involved in the study about the potential applications and conclusions that could be drawn from their findings. For instance:
"Low genetic diversity is appearing as a common theme in the extinct species being studied by our team."
Which again, on the face of it, is "duh". Low genetic diversity means a species is going to be inherently more at risk to disease and other pressures. See again the Tasmanian devil, the cheetah, the African wild dog, the Irish potato famine (monoculture of potatoes all wiped out by a disease), and a long list of others. But the quotes (and the better articles) take it a step further, such as these from three different scientists from the study:
"The prospect that comparison of mitochondrial sequences of ancient DNA samples could provide information useful for understanding the process of extinction ... can be immediately applied to currently endangered species."
and
"We are in the middle of one of the largest mass extinctions ever, and this kind of data from a species that did not survive is very interesting."
and
"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."
All of which is indeed very interesting, at least to me. Pedigrees and genetic diversity is already a huge consideration in species conservation efforts, especially in zoos. It will be interesting to see how this kind of thinking and historical genetic diversity research plays out in species planning. Moreover, it's a good thought-provoking exercise when you apply it to another species with a surpisingly low genetic diversity, all things considered:
homo sapiens.
Humans have a very low level of genetic diversity compared to, say, the common chimpanzee. Our species went through a near-extinction bottleneck event some time back (estimates are in the 60-75 thousand year range). We've rebounded pretty well since then, genetically speaking, but as our world rapidly changes around us, we should still keep it in mind - because that lack of diversity still has the potential to bite us in the butt when it comes to our ability to adapt.
Food for thought!
Just a few days ago, a journal article came out about a multinational effort to extract and map the mitochondrial DNA of the Tasmanian tigers based on two different samples preserved on two different continents. The immediate reporting around the findings concentrated heavily on how nearly identical the two samples were, and one article in particular emphasized how surprising that was.
To which I immediately said to myself, well, duh! This seemed perfectly obvious to me (and I have to admit the "and the samples came from continents apart!" comment in the article made me really roll my eyes, because while the samples might now exist continents apart, both animals came from the island of Tasmania at the end of the 19th century). I didn't find it at all surprising that the species would have had very low genetic diversity. It was an island species that had isolated off from a continent-isolated species forebear. Tasmania's arguably most famous animal, the Tasmanian devil, is a very isolated species with extremely low genetic diversity. I would have been surprised if there *had* been a great span of genetic diversity between the two Tasmanian tiger samples.
So, duh.
What was not-so-duh and in fact quite thought-provoking were quotes from some of the scientists involved in the study about the potential applications and conclusions that could be drawn from their findings. For instance:
"Low genetic diversity is appearing as a common theme in the extinct species being studied by our team."
Which again, on the face of it, is "duh". Low genetic diversity means a species is going to be inherently more at risk to disease and other pressures. See again the Tasmanian devil, the cheetah, the African wild dog, the Irish potato famine (monoculture of potatoes all wiped out by a disease), and a long list of others. But the quotes (and the better articles) take it a step further, such as these from three different scientists from the study:
"The prospect that comparison of mitochondrial sequences of ancient DNA samples could provide information useful for understanding the process of extinction ... can be immediately applied to currently endangered species."
and
"We are in the middle of one of the largest mass extinctions ever, and this kind of data from a species that did not survive is very interesting."
and
"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."
All of which is indeed very interesting, at least to me. Pedigrees and genetic diversity is already a huge consideration in species conservation efforts, especially in zoos. It will be interesting to see how this kind of thinking and historical genetic diversity research plays out in species planning. Moreover, it's a good thought-provoking exercise when you apply it to another species with a surpisingly low genetic diversity, all things considered:
homo sapiens.
Humans have a very low level of genetic diversity compared to, say, the common chimpanzee. Our species went through a near-extinction bottleneck event some time back (estimates are in the 60-75 thousand year range). We've rebounded pretty well since then, genetically speaking, but as our world rapidly changes around us, we should still keep it in mind - because that lack of diversity still has the potential to bite us in the butt when it comes to our ability to adapt.
Food for thought!
