An international team of researchers from Australia, Argentina and Chile has found the answer to one of natural history’s most intriguing puzzles – the origins of the now extinct Falkland Islands wolf (Dusicyon australis).
The Falkland Island wolf (John Gerrard Keulemans, via biodiversitylibrary.org)
The Falkland Islands wolf, also known as the Antarctic wolf, the warrah, the Falkland Islands dog or Falkland Islands fox, was the only native land mammal of the Falkland Islands. Previous theories have suggested the wolf somehow rafted on ice or vegetation, crossed via a now-submerged land bridge or was even semi-domesticated and transported by early South American humans.
The 320-year-old mystery was first recorded by early British explorers in 1690 and raised again by Charles Darwin following his encounter with the famously tame species on his Beagle voyage in 1834.
The team extracted tiny pieces of tissue from the skull of a specimen collected personally by Darwin. They also used samples from a previously unknown specimen, which was recently re-discovered as a stuffed exhibit in the attic of Otago Museum in New Zealand.
The findings, published in the journal Nature Communications, show that the Falkland Islands wolf only became isolated about 16,000 years ago around 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,” said lead author Prof Jeremy Austin from the University of Adelaide’s Australian Centre for Ancient DNA.
“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.”
The results show that D. avus was the closest relative of the Falkland Islands wolf and they separated only 16,000 years ago – but the question of how the island colonization came about remained. The absence of other mammals argued against any land bridge connection to the mainland.
“The Eureka moment was finding evidence of submarine terraces off the coast of Argentina,” said senior author Prof Alan Cooper, also from the Australian Centre for Ancient DNA. “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 20 km) 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.”
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Bibliographic information: Austin JJ et al. 2013. The origins of the enigmatic Falkland Islands wolf. Nature Communications 4, article number: 1552; doi: 10.1038/ncomms2570
