When Charles Darwin visited the Falkland Islands during the voyage of the Beagle in 1835, he saw a wolf-like species, wrote about it in his diaries and correctly commented that it was being hunted in such large numbers that it would soon become extinct.
Darwin was baffled by how this animal got on the islands, and it figured heavily in the formation of his ideas on evolution by natural selection.
Now, UCLA biologists and colleagues have analyzed DNA from museum specimens, including one collected by Darwin, and have solved the puzzle. Their results surprised them.
"It was the only terrestrial mammal on the island," said Robert Wayne, UCLA professor of ecology and evolutionary biology and co-author of the research paper, published Nov. 3 in the journal Current Biology. "How can something the size of a Labrador retriever end up on an island in sufficient numbers that a new population emerges and evolves into a new species? The presence of this large canid, the Falkland Islands wolf, has always been a puzzle, since the early 1800s."
Was it brought to the Falklands, less than 300 miles from the mainland of South America, by humans or did it somehow get there by itself?
"Our analysis rules out humans," said Graham Slater, a postdoctoral scholar in the UCLA Department of Ecology and Evolutionary Biology and lead author of the paper.
Slater, Wayne and colleagues analyzed DNA samples from five Falkland Islands wolves and calculated how long ago those five wolves shared a common ancestor.
"It was at least 70,000 years ago — well before humans came to the New World," Slater said. "The Falkland Islands wolf clearly precedes any possible human occupation of the New World, which dates back some 12,000 to 13,000 years."
Darwin hypothesized that the Falkland Islands wolf, which became extinct in 1876, may have come to the islands on icebergs. Wayne and Slater think Darwin may be right.
"A large, wolf-size animal could perhaps live on a large iceberg with penguins and sea birds and maybe seals — enough prey to survive the voyage — where a vegetarian could not do that very well," Wayne said. "There is a possibility that a pack of wolf-like animals (which are members of the biological family of mammals that includes wolves, foxes, coyotes, jackals and domestic dogs) could be marooned on an iceberg that would eventually land at the shores of the Falkland Islands, then live off the sea birds and marine mammals there and give rise to a new population that over time would turn into a dramatically different species."
"If you look at Darwin's notebooks, the first time he ever raised the idea that species are not fixed entities was after he considered birds from the Galapagos Islands," Slater said. "He is talking about how they are different from island to island, and he says, 'The only other example I can think of is the wolves of the Falkland Islands.' Then, the next sentence is the first time he ever said, 'This leads me to believe that species are not fixed entities and change over time.' When Darwin first was thinking that species evolve, he had the Falkland Islands wolf in mind."
The closest relative to the Falkland Islands wolf, the biologists report, is an odd South American dog species called the maned wolf, which looks nothing like the Falklands species.
"The closet living relative of the maned wolf is the bush dog, which is even more different," Slater said. "These three are a strange group."
"That was a shock to us," Wayne said. "You wouldn't have guessed by looking at them that that the maned wolf and the bush dog could give rise to something like a Falkland Islands wolf, but we have verified it."
"No one has ever suggested that before," Slater said.
The maned wolf, which lives on the grassy plains of Brazil and parts of Argentina, has long, thin legs and is often called the "fox on stilts." The bush dog, which lives in South American rain forests, is tiny, "like a toaster with legs on it," Wayne said. The bush dog hunts large rodents and animals that are much larger than itself, Slater said.
"Our findings firmly align the Falkland Islands wolf with the maned wolf, even though the divergence was fairly ancient, more than 6 million years," Wayne said. "They both probably evolved more than 6 million years ago in North America."
The research was federally funded by the National Science Foundation.
Wayne and Slater collected and analyzed DNA from five Falkland Islands wolves from the British Museum and museums in Philadelphia, Liverpool and New Zealand.
"We sequenced some regions of the mitochondrial genome," Wayne said. The mitochondria are the tiny powerhouses of the cell, whose generators burn food and produce most of a cell's energy. "We also analyzed gene sequences of the nucleus of the cell."
They sequenced sites in the genome of the cell nucleus that are found only in certain groups of related canids, such as South American foxes, the maned wolf and the bush dog; these species have a unique nucleotide DNA sequence.
Previously, some scientists thought the Falkland Islands wolf may have been a domesticated animal from the South American mainland that was brought over by native South Americans and was marooned on the islands.
"The problem is, as far as we know, there were never any permanent settlements on the Falkland Islands before European explorers arrived," Wayne said. "There has been no evidence to my mind of any kind of prehistoric occupation of the Falkland Islands; they are too remote, cold and not very hospitable."
Co-authors on the paper include Olaf Thalmann, a UCLA postdoctoral scholar in Wayne's laboratory; Jennifer Leonard, who earned her Ph.D. from UCLA and is now on the faculty of Sweden's Uppsala University; Rena Schweizer, a UCLA graduate student in Wayne's laboratory; Klaus-Peter Koepfli, a UCLA postdoctoral scholar in Wayne's laboratory; John Pollinger, Wayne's laboratory manager; Nicolas J. Rawlence; Jeremy J. Austin; and Alan Cooper.
In previous research, Wayne and colleagues used molecular genetic techniques to determine that dogs have ancient origins and that the first Americans to arrive in the New World more than 12,000 years ago brought domesticated dogs with them. They have also found that dogs have been living in close association with humans much longer than any other domestic animal, have confirmed that dogs evolved from wolves and have confirmed that today's domestic horse resulted from the interbreeding of many lines of wild horses in multiple locations and was not confined to a small area or a single culture. They also showed that nearly half of North American wolves have black coats as the result of historical matings between black dogs and wild gray wolves.
UCLA is California's largest university, with an enrollment of nearly 38,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer more than 323 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Five alumni and five faculty have been awarded the Nobel Prize.
For more news, visit the UCLA Newsroom or follow us on Twitter.
Stuart Wolpert | EurekAlert!
One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie
The dark side of cichlid fish: from cannibal to caregiver
20.04.2018 | Veterinärmedizinische Universität Wien
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy