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Utilizing BIOCLIM, the computer program he created to define the environmental
"envelopes" that constrain the distribution of species of plants and animals,
and predict their potential ranges, Nix produced a map which depicts the
optimum environment for thylacines - the grasslands and open woodlands
of northern Tasmania.
Nix then compiled all
post-1933 sightings of thylacine-like animals, assigning them to three
independent data sets - presumed reliable, possibly reliable, and crank
sightings - and superimposed them on the BIOCLIM map of optimum thylacine
habitat.
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reliable" and "possibly reliable" overlapped almost perfectly with BIOCLIM's
prediction of where thylacines were most likely to be. The Tasmanian
regions of most frequent sightings coincided with two small "hot spots"
of prime habitat identified by BIOCLIM. Nix has since undertaken
a similar study - with very similar results - for the intermittent sightings
of "thylacines" in Victoria. BIOCLIM suggests that the Wilson's Promontory
region is a good habitat, along with the isolated Grampians mountain range
in southwestern Victoria, and the southwest of Western Australia, which
has also reported a number of alleged thylacine sightings in recent decades. |
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The wilderness of Wilson's
Promontory, the southernmost point of Victoria. Because the many
reports of alleged thylacine sightings here concur with BIOCLIM's predictions
on areas of suitable habitat, it is suspected that thylacines may
possibly reside in this area. The region is fortunately a
national park, and thus this refuge is protected from development.
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Nix advises that a thorough
search for living thylacines be made before expending considerable resources
in an attempt to clone the species from DNA samples.
By mid-2002, after over
two years of intensive research, the Australian Museum succeeded in replicating
individual thylacine genes using the PCR (Polymerase
Chain Reaction) process. Although this means that cloned thylacines
are now one step closer to becoming a reality, there are still a number
of very significant obstacles to overcome. Among these is the fact
that the quality of the DNA which was extracted from preserved tissue samples
has proven to be quite poor, and is perhaps too badly degraded to even
construct a thylacine DNA library, which is a prerequisite task.
With the passage of
several more years of effort, by February 2005 the Australian Museum made
the decision to discontinue its involvement with the thylacine cloning
project. According to a media statement by the museum's current Director
Frank Howarth and Assistant Director of Science and Collections Dr. Les
Christidis, although the museum does possess sufficient expertise to attempt
to reconstruct a thylacine DNA library, it lacks the facilities and skill
to conduct "further stages requiring cell culture". The cell culture
stage of the project is necessary to enable cells from other species to
act as hosts for the reconstructed thylacine genome.
Dr. Archer, who launched
the thylacine cloning project in 1999, says that it has lost its momentum
since his contract as museum director ended in 2003. Now Dean of
Science at the University of New South Wales, Archer still remains hopeful
that cloning of the thylacine will eventually become possible.
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These
vials contain a set of thylacine DNA extractions from different tissue
types. To better the chances of obtaining high quality gene sequences,
samples of tissue were taken from various parts of the preserved thylacine's
body. Cells from deep inside the body are preferable to this purpose,
as there is less of a possibility that they have been contaminated with
genetic material from the outside world (e.g. from bacteria, fungi, etc.).
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"I and
other colleagues remain interested in the project and I don't think that
it will simply die because the museum can't proceed," he says. "The
technology to make it happen is improving all the time. And I believe
science has a duty to continue to assemble the building blocks that will
be needed to do it." Archer says that the technology for recovering
degraded DNA and extracting it from museum specimens is advancing.
Also, that DNA recovered from dried specimens may be just as good if not
better than that obtained from the museum's alcohol preserved specimen
which dates from 1866. |
Dr. Archer confirmed
in October 2005 that he was assembling a new team to revive the cloning
project. He says that public interest in the project is still strong
and researchers from several Australian institutions have expressed interest
in becoming involved. "In addition, US researchers with genetic sequencing
capabilities will be involved for the first time and their expertise is
expected to open up new possibilities for bringing the project closer to
its ultimate goal," he said.
In October of 2002,
when the project was still underway at the Australian Museum, I was given
a tour of the museum's genetic laboratory. My illustrated account
can be viewed here. |