The Falkland Islands wolf, long extinct, is the only land-based mammal native to the islands. European explorers in the 17th century were puzzled by the presence of this lone mammalian species, as was Charles Darwin.
Now, researchers writing in Nature Communications suggest that the wolf traveled across a thin, shallow strait from the mainland to the islands during the last glacial maximum.During this period, about 18,000 to 25,000 years ago, the strait would periodically freeze over.
"This wolf was likely tracking penguins, seals and sea birds that were hauling out onto the ice," said Dr. Alan Cooper, an evolutionary biologist at the University of Adelaide in Australia.
The scientists believe the wolf crossed the strait from what is now Argentina. "The question is, how did this great big mammal get over when rodents didn't?" he said.
Dr. Cooper and his colleagues compared DNA samples from the wolf with those of one of its closest mainland relatives, an extinct foxlike species called Dusicyon avus. They found that the two species separated about 16,000 years ago, coinciding with the last glacial maximum and the frozen marine strait.
Previously, it had been theorized that the wolf was semi-domesticated and brought to the island by humans.
The last Falkland Islands wolf was spotted in the late 19th century.
----- Taken form TODAY Saturday Edition, April 06, 2013
Mimicry in Butterflies Is Seen here on These Classic “Plates” Showing Four Forms of H. numata, Two Forms of H. melpomene, and the Two Corresponding Mimicking Forms of H. erato. This highlights the diversity of patterns as well as the mimicry associations, which are found to be largely controlled by a shared genetic locus [15]. (Photo credit: Wikipedia)
This is an article lifted from TODAY's Science and Technology section, 06-April-2013; I have kept for the purpose of posting in this blog at a later date (which turns out to be more than a year later...)
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Perhaps no destination has inspired more great naturalists than Brazil. Charles Darwin first made landfall at Bahia in 1832; Alfred Russel Wallace and Henry Walter Bates arrive at Para in 1848. Wallace roamed the Amazon for four years, and the indefatigable Bates for 11.
In 1852, a naturalist named Fritz Muller arrive from Germany. While Darwin and Wallace would conceive of the theory of evolution by natural selection, its acceptance was aided by Bates and Muller. And thanks to Bates and Muller, no creatures contributed more to the early growth of evolutionary science than butterflies.
Bates noticed species whose wing patterns resembled those of other butterfly families in the area. In puzzling this out, he realized that harmless butterflies were mimicking noxious species that were unpalatable to birds and lizards, and therefore, not attacked by predators.
A few years after Darwin published "On the Origin of Species," Bates suggested that this sort of mimicry - now called "Batesian" - was proof of the principle of natural selection.
Muller crucially observed that unpalatable butterflies were also mimicking other species of unpalatable butterflies. If they were already unpalatable, he wondered, what added advantage was there to mimicking other species?
It dawned on him that unpalatable mimics would enjoy strength in numbers: Their unpalatability had to be learned by predators, and species would share the cost of those lessons, whereas a uniquely patterned unpalatable species would bear the full cost.
Natural selection thus explained why different species' wing patterns would converge. But how were such similar but complex wing color patterns generated by different species? The answer eluded scientists for nearly 150 years, until an international team of researchers recently revealed mimicry's innermost secrets.
There are two ways in which what is still called "Mullerian mimicry" could evolve: Either each species independently evolved mutations that led to very similar wing patterns, or patterning genes were exchanged among species.
Several genes controlling the production of the wing patterns have now been identified, enabling researchers to distinguish between these alternatives. The answers? Both mechanisms have been at work.
By analyzing the DNA sequences in two mimicking Heliconius species in South America, researchers could determine that each species had independently evolved up to 20 different patterns that were nearly identical in each species. But in more closely related mimicking species, they found that color-controlling genes had been exchanged.
It is astonishing that so many patterns could be independently generated and replicated in different species. And it is surprising to have species swapping genes. After all, the inability to breed successfully with other groups has long been an operational definition of species.
Even if such interspecies matings are rare, a gene that confers a strong advantage, like mimicry, can spread quickly through a population.
Darwin referred to Muller as the "prince of observers," and although they never met, Muller considered Darwin a second father.
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Lifted from TODAY Saturday Edition, April 6, 2013; The New York Times International Weekly
The fossil is believed to be an ancestor of monkeys, humans and other primates.
(CNN) -- Scientists hailed Tuesday a 47-million-year-old fossil of an ancient "small cat"-sized primate as a possible common ancestor of monkeys, humans and other primates.
Scientists say the fossil, dubbed "Ida," is a transitional species, living around the time the primate lineage split into two groups: A line that would eventually produce humans, primates and monkeys, and another that would give rise to lemurs and other primates.
The fossil was formally named Darwinius masillae, in honor of the anniversary of Charles Darwin's 200th birthday.
"This is the most complete primate fossil before human burial," said Dr. Jorn Hurum, of the Natural History Museum at the University of Oslo, who led the study of the fossil, a young female primate.
However, because it was split into two parts, its significance was not immediately recognized.
An international team of scientists, which Hurum led, conducted a detailed forensic analysis of the fossil for the past two years, the release said.
Hurum nicknamed the fossil Ida after his young daughter, he said.
The fossil's body is nearly complete; only part of one leg is missing, according to Hurum. In addition to the bones, the softer features are also preserved, as are the remnants of its last meal: fruits, seeds and leaves, which were found in Ida's gut, according to the scientists.
"It's such a beautiful specimen," Hurum said of Ida. He said the fossil is about 2 feet long, "like a small cat in size."
The fossil has both adult and baby teeth, indicating that it was weaned and about 9 months old when it died, the PLoS article said.
She would have eventually grown to the size of a lemur, the article said.
The young primate fossil does not have two crucial anatomical features found in lemurs: a grooming claw on the second digit of its foot and a fused row of teeth in the middle of its lower jaw, known as a toothcomb, the scientists said.
X-rays revealed a broken wrist, which the team of scientists believe may have contributed to Ida's death, according to a news release from the museum at Oslo.
Ida may have been overcome by carbon dioxide gas while drinking from the Messel lake, which was often covered by a low-lying blanket of the gas, the news release said. Hampered by the broken wrist, the young primate may have fallen into unconsciousness and may have slipped into the lake. The primate sunk to the bottom and was preserved for 47 million years, the news release said.
The fossil is believed to be an ancestor of monkeys, humans and other primates.
(CNN) -- Scientists hailed Tuesday a 47-million-year-old fossil of an ancient "small cat"-sized primate as a possible common ancestor of monkeys, humans and other primates.
Scientists say the fossil, dubbed "Ida," is a transitional species, living around the time the primate lineage split into two groups: A line that would eventually produce humans, primates and monkeys, and another that would give rise to lemurs and other primates.
The fossil was formally named Darwinius masillae, in honor of the anniversary of Charles Darwin's 200th birthday.
"This is the most complete primate fossil before human burial," said Dr. Jorn Hurum, of the Natural History Museum at the University of Oslo, who led the study of the fossil, a young female primate.
However, because it was split into two parts, its significance was not immediately recognized.
An international team of scientists, which Hurum led, conducted a detailed forensic analysis of the fossil for the past two years, the release said.
Hurum nicknamed the fossil Ida after his young daughter, he said.
The fossil's body is nearly complete; only part of one leg is missing, according to Hurum. In addition to the bones, the softer features are also preserved, as are the remnants of its last meal: fruits, seeds and leaves, which were found in Ida's gut, according to the scientists.
"It's such a beautiful specimen," Hurum said of Ida. He said the fossil is about 2 feet long, "like a small cat in size."
The fossil has both adult and baby teeth, indicating that it was weaned and about 9 months old when it died, the PLoS article said.
She would have eventually grown to the size of a lemur, the article said.
The young primate fossil does not have two crucial anatomical features found in lemurs: a grooming claw on the second digit of its foot and a fused row of teeth in the middle of its lower jaw, known as a toothcomb, the scientists said.
X-rays revealed a broken wrist, which the team of scientists believe may have contributed to Ida's death, according to a news release from the museum at Oslo.
Ida may have been overcome by carbon dioxide gas while drinking from the Messel lake, which was often covered by a low-lying blanket of the gas, the news release said. Hampered by the broken wrist, the young primate may have fallen into unconsciousness and may have slipped into the lake. The primate sunk to the bottom and was preserved for 47 million years, the news release said.
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