The Falklands Wolf: A Darwin Mystery Solved
When Charles Darwin's reached the Falkland Islands on his famed voyage, he discovered there a "large wolf-like fox" found nowhere else in the world. "As far as I am aware," he would later write in The Voyage of the Beagle, "there is no other instance, in any part of the world, of so small a mass of broken land, distant from a continent, possessing so large an aboriginal quadruped peculiar to itself." The human population on the island, however, was quickly increasing and the canid's numbers were dwindling. Darwin predicted the species would soon go the way of the dodo, and he was right. The species went extinct in 1876, killed off for its fur and to protect the sheep population.
Since Darwin's time, scientists have puzzled over his wolf-like canid, now known as the Falklands wolf. The species was the only native terrestrial mammal found on the island; there were no mice or porcupines or deer. And the islands lie 300 miles from the mainland. Where did the wolf come from and how did it get to the Falklands? Could Native Americans have brought the wolves to the island?
To get a picture of the wolf's history, scientists isolated DNA from four museum specimens of the Falklands wolf, including one that had been collected by Darwin himself. (Their study appears in Current Biology.) They compared the DNA of their specimens with that of other canids, including several South American species (foxes, the maned wolf, and the bush dog) and members of the Canis genus (which includes the gray wolf and coyotes). With the DNA data, they created a phylogenetic tree that let the scientists see which species were the most closely related to the Falklands wolf and when the Falklands wolf branched off as a new species (that is, when they became isolated on the islands).
The four museum specimens diverged from their closest relatives about 70,000 years ago, which the scientists think is when the species came to the Falkland Islands. That was during the last ice age and long before humans showed up in the area (nixing the Native American theory). The wolves probably floated to the islands on ice or logs or perhaps walked over a glacier. Once on the islands, they would have feasted on penguins, geese and pinnepeds.
The scientists now have a new mystery: The analysis revealed the maned wolf to be the Falklands wolf's closest relative, but the two species diverged from each other over 6 million years ago, several million years before canids populated South America from the north. There aren't yet any canid fossils from this time period—something to look for.