March 6, 2013
Ancient DNA Helps Solve The Mystery Of The Extinct Falkland Islands Wolf
April Flowers for redOrbit.com - Your Universe Online
A research group from the University of Adelaide has found the answer to one of natural history's most intriguing puzzles — the origins of the now extinct Falkland Islands wolf. The new study also reveals how the wolf came to be the only land-based mammal on the islands, which are almost 300 miles from the Argentina mainland.
According to prior theories, the wolf somehow rafted on ice or vegetation, crossed a now-submerged land bridge, or perhaps was semi-domesticated by early South American humans. The mystery of the wolf was first recorded in 1690 by early British explorers. Charles Darwin raised it again following his encounter with the famously tame species on his 1834 voyage aboard the H.M.S. Beagle.
Tiny pieces of tissue were extracted from the skull of a specimen collected personally by Darwin. The research team from the University's Australian Centre for Ancient DNA (ACAD) also used samples from a previously unknown specimen, recently rediscovered as a stuffed exhibit in the attic of Otago Museum in New Zealand.
Unlike earlier findings, the new study concludes that the Falkland Islands wolf, Dusicyon australis, became isolated approximately 16,000 years ago during the peak of the last glacial period.
"Previous studies used ancient DNA from museum specimens to suggest that the Falkland Islands wolf diverged genetically from its closest living relative, the South American maned wolf (Chrysocyon brachyurus) around seven million years ago. As a result, they estimated that the wolf colonized the islands about 330,000 years ago by unknown means," says Associate Professor Jeremy Austin, Deputy Director of ACAD.
"Critically, however, these early studies hadn't included an extinct relative from the mainland, the fox-like Dusicyon avus. We extracted ancient DNA from six specimens of D. avus collected across Argentina and Chile, and made comparisons with a wide group of extinct and living species in the same family."
D. avus was revealed by the analysis as the closest relative of the Falkland Islands wolf. The two species separated only 16,000-years ago, but that did not answer the question of how the island was colonized. The theory of a land bridge connected to the mainland is discounted by the absence of other mammals on the island.
"The Eureka moment was finding evidence of submarine terraces off the coast of Argentina," says Professor Alan Cooper. "They recorded the dramatically lowered sea levels during the Last Glacial Maximum (around 25-18,000 years ago)."
"At that time, there was a shallow and narrow (around 20km) strait between the islands and the mainland, allowing the Falkland Islands wolf to cross when the sea was frozen over, probably while pursuing marine prey like seals or penguins. Other small mammals like rats weren't able to cross the ice."
The findings of this study were published in a recent issue of Nature Communications.