DNA from an extinct wolf solves 320-year-old mystery

A team of international researchers has found the answer to one of natural history’s most intriguing puzzles: the origins of the now extinct Falkland Islands wolf and how it came to be the only land-based mammal on the isolated islands, 460 kilometres from the nearest land, Argentina.

Previous theories have suggested that the wolf may have rafted to the islands on ice or vegetation, crossed via a now submerged land bridge, or was 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 tame species on his voyage in the Beagle in 1834.

The team of eight researchers from Argentina, Australia and Chile concluded that, contrary to earlier theories, the Falkland Islands wolf – or Dusicyon australis – only became isolated about 16,000 years ago around the peak of the last glacial period.

In previous studies, scientists used ancient DNA from museum specimens and argued that the wolf had diverged genetically from its closest living relative, the South American maned wolf, about seven million years ago. As a result, they estimated the wolf had colonised the islands 330,000 years ago by unknown means.

But the latest researchers say that the early studies did not include DNA from an extinct relative from the mainland, the fox-like Dusicyon avus. So they extracted ancient DNA from six specimens of the animal collected across Argentina and Chile, and compared the DNA with a wide group of extinct and living species in the same family.

Analyses conducted by scientists at the Australian Centre for Ancient DNA at the University of Adelaide showed that D avus was the closest relative of the Falkland Islands wolf and that the two species had separated a mere 16,000 years ago.

That left the question of how the island colonisation came about, given that the absence of other mammals argued against any land bridge connection to the mainland.

What the researchers call the ‘Eureka moment’ came when evidence was found of submarine terraces off the coast of Argentina. These recorded dramatically lowered sea levels during the last glacial maximum 25,000 to 18,000 years ago, when vast quantities of the oceans were locked up in ice.

At that time, a shallow and narrow strait about 20 kilometres wide separated the islands from the mainland. The scientists believe this would have allowed the wolf to cross when the sea was frozen over, probably while pursuing marine prey such as seals or penguins. They think that other small mammals such as rats were not able to cross the ice.

A report on the findings was published in Nature Communications on Wednesday.