NSWTR 2024 HR - Flipbook - Page 53
YEAR 9-10 SECTION
ONE (VERY BIG) FAMILY
We can estimate how long ago (or how recently) two
species diverged from each other by comparing how many
genes they have in common. The human genome contains
around 20,000 genes, 99.9% of which are identical to
genes in other humans. We share around 90% of our genes
with chimpanzees because they’re our closest relatives –
we became di昀昀erent species 4-6 million years ago. 75%
of genes that cause disease in humans are also found in
fruit 昀氀ies, making them an ideal model organism to study
human disease.
To come up with these numbers, scientists used a
process called genome sequencing, which involves
sequencing, every single gene in a species’ genome.
Genome sequencing allows conservationists to identify
new species of plants and animals so they can be
protected, and it’s even helping to resurrect lost species.
THE DE-EXTINCTION CHALLENGE
Bringing species back from the dead used to be the stu昀昀 of
science 昀椀ction, but it’s becoming less far-fetched the more
we learn about genetics. Here in Australia, researchers are
working to bring back one of our most iconic animals: the
Tasmanian tiger, or thylacine.
Thylacines were declared extinct in 1982 (though none
had been seen since 1936). Their DNA, however, lives
on through hundreds of museum samples. Using these
samples, University of Melbourne researchers created a
昀椀rst draft of the thylacine genome in 2018. Now, they’re
昀椀lling in the gaps, thanks to genome sequencing of the
thylacine’s closest living relative: the numbat!
Ultimately, they hope to use this information to
genetically engineer a creature that’s almost an exact
thylacine match.
ECHIDNA . CREDIT: ENGUERRAND BLANCHY/UNSPLASH
THE THYALCINE DILEMMA
Although thylacines were hunted to extinction by
humans, the genetic diversity of thylacines began
to diminish about 70,000 years ago. Reduced
genetic diversity makes a population more
susceptible to disease and can ultimately cause it
to go extinct. Usually, it occurs when populations
get smaller or are isolated from others in their
species. In the case of thylacines, it was probably
both; scientists think that thylacine numbers began
to decline around the last Ice Age, and then more
when the species was isolated in Tasmania.
Paying attention to the genetic diversity of
today’s species could be the key to saving them.
If scientists can identify that a species’ genetic
diversity is declining, they can act to reverse
it through captive-breeding programs and
translocations. Zoos Victoria, for example, bred
more than 650 eastern barred bandicoots in
captivity to help re-establish wild populations
after the species was declared ‘extinct in the wild’.
Today, these furry little marsupials are recovering;
in 2021, the species made international headlines
when it became the 昀椀rst in the world to have its
conservation status upgraded to ‘endangered’.
Extinction is a natural part of evolution, but
human activities have dramatically increased
the rate at which Earth is losing species. Habitat
destruction, roads, introduced species and climate
change are all having a big impact. But thanks to
our growing understanding of DNA and genetics,
we now have some tools up our sleeve to help our
fellow Earth-dwellers survive.
MEET THE RELATIVES
Did you know? We share 69% of our genes with
platypuses and 24% with rice!
FEMALE THYLACINE (FRONT) WITH JUVENILE MALE OFFSPRING
(REAR). CREDIT: BAKER; E.J. KELLER. REPORT OF THE
SMITHSONIAN INSTITUTION. 1904 FROM THE SMITHSONIAN
INSTITUTION ARCHIVES. WIKIMEDIA/PUBLIC DOMAIN.
DOWNLOAD ALL OF THE LINKS IN THIS BOOKLET
AT WWW.SCIENCEWEEK.NET.AU/SCHOOLS/2024RESOURCE-BOOK-LINKS/
SPECIES SURVIVAL – MORE THAN JUST SUSTAINABILITY
READ MORE
WE’VE DECODED THE NUMBAT GENOME
– AND IT COULD BRING THE THYLACINE’S
RESURRECTION A STEP CLOSER
(THE CONVERSATION)
DNA SPELLS EVOLUTION
(KHAN ACADEMY VIDEO)
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