Genetic analysis of the now-extinct Falkland Islands Wolf has answered a biological riddle that caught the attention of a young Charles Darwin, and helped shape his understanding of evolution.

During his voyage aboard the HMS Beagle, Darwin observed that the wolves — like his now-famous finches — varied widely in size between different islands, suggesting that the traits of species were not immutable, but changed over time in response to their environments.

Darwin also wondered at the origins of the wolves, which were unusually small, and had reddish fur and relatively short jaws. He dubbed them foxes, and was the first of many scientists to suspect that the strange canids weren't wolves at all. Others thought they were descended from dogs brought by the islands' first human settlers. Indeed, not a single mammal species other than the wolf was native to the Falkland Islands, located 300 miles off the southeastern tip of South America.

In a study published Tuesday in* Current Biology*, researchers address these questions with a genetic analysis of five museum specimens. Their findings are twofold. First, the specimens last shared a common ancestor 70,000 years ago, or a full 50,000 years before humans sailed to the Falklands; and the animals' closest relative is the maned wolf, still found on the savannas of South America.

Moreover, the split from the maned wolf appears to have occurred 6.7 million years ago — some four million years before wolves are known to have lived in South America. At that time, maned wolves lived in North America, and it seems that all of South America's canids originated in the north.

Unfortunately, by the time Darwin arrived in the Falklands, the wolves were being killed for their fur, and their numbers were in decline. "Within a very few years after these islands shall have become regularly settled, in all probability this fox will be classed with the dodo, as an animal which has perished from the face of the earth," he wrote.

Forty years later, the Falklands Islands wolf was gone.

Image: From Zoology of the Voyage of the H.M.S. Beagle

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Citation: "Evolutionary history of the Falklands wolf." By Graham J. Slater, Olaf Thalmann, Jennifer A. Leonard, Rena M. Schweizer, Klaus-Peter Koepﬂ, John P. Pollinger, Nicolas J. Rawlence, Jeremy J. Austin, Alan Cooper, and Robert K. Wayne. Current Biology, Vol. 19 Issue 20, November 3, 2009.

Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecosystem and planetary tipping points.