On the Galapagos Islands, where Charles Darwin’s observations led to his evolutionary theory, scientists are now reporting that they’re witnessing a single species splitting into two, according to a new paper in the Proceedings of the National Academy of Sciences.
A husband and wife team, Peter and Rosemary Grant of Princeton University, have spent the past 36 years studying Darwin’s finches, technically know as tanagers. Darwin‘s observations of the birds during his voyage to the Galapagos on the HMS Beagle helped him arrive at the idea of evolutionary divergence: when different populations of a single species become geographically isolated, and evolve in different directions. The Grants have pushed that work further, with decades of painstaking observations providing a real-time record of evolution in action. In the PNAS paper, they describe something Darwin could only have dreamed of watching: the birth of a new species [Wired.com]. The process has been taking place with the help of a little bit of chance and a special song.
Mosquitoes that have made their way to the Galapagos Islands via tourist planes and boats are threatening the rare native species endemic to the region, according to a study published in the journal Proceedings of the Royal Society B.
Culex quinquefasciatus, known as the southern house mosquito, can carry diseases dangerous to wildlife, such as avian pox and West Nile virus. Not only have the insects hopped a ride onto the islands, but they’ve also bred with native species once they reach the shore, the study found. That means they pose an ongoing threat to the Galapagos’ rare species and delicate ecosystem, which inspired Darwin’s theory of evolution after he observed the island’s unique array of wildlife. “You only need a single infectious mosquito to initiate a disease cycle,” [co-author Simon] Goodman…[T]he Galapagos “have globally important biodiversity — endemic species found nowhere else in the world,” said Goodman [Telegraph].
A husband and wife team that for 35 years has researched finches’ evolutionary responses to environmental changes have won the prestigious Kyoto Prize in the basic sciences category. Peter and Rosemary Grant, both emeritus professors at Princeton University, have studied finches that lives on the Galapagos Islands for decades and will share the $515,000 prize. The Kyoto Prize is a Japanese award similar to the Nobel Prize.
The two evolutionary biologists devoted their careers to furthering Charles Darwin‘s theory of evolution. Both 72, the Grants have been traveling regularly since 1973 to the Galápagos, the remote islands west of Ecuador. There, they have painstakingly recorded the characteristics of numerous varieties of finches [Philadelphia Inquirer]. Darwin stumbled upon these finches during his famous tour of the Galapagos Islands in 1835, later chronicled in his book The Voyage of the Beagle.
The mighty tortoises that roam the Galapagos Islands may not have many predators, but a new study suggests that the giant reptiles could run into serious problems due to the diminutive black salt marsh mosquito. Researchers genetically analyzed the mosquito, and found that it was not introduced recently by humans but instead arrived about 200,000 years ago. Since then the insect has evolved so much it is practically a distinct species from the mainland variety. For one thing, the insect has adapted to be able to feast on the blood of lizards, tortoises and other reptiles and not solely on mammals, as it does on the mainland [The New York Times].
That diversity of diet is what has researchers worried. If the black salt marsh mosquito picks up a disease like avian malaria or West Nile fever, it could quickly spread the disease to the Galapagos’s rare tortoises and marine iguanas. Says study coauthor Andrew Cunningham: “With tourism growing so rapidly the chance of a disease-carrying mosquito hitching a ride from the mainland on a plane is also increasing, since the number of flights grows in line with visitor numbers…. If a new disease arrives via this route, the fear is that Galapagos’ own mosquitoes would pick it up and spread it throughout the archipelago” [Telegraph].
Charles Darwin‘s theory of evolution may have been shaped by his abhorrence of slavery as much as by his keen observations of Galapagos finches, a new book argues. Darwin’s Sacred Cause, by Adrian Desmond and James Moore, notes that slavery propaganda of the time often claimed that different races belonged to different species, a notion that Darwin’s work obliterated. The book suggests that Darwin’s unique approach to evolution – relating all races and species by “common descent” – could have been fostered by his anti-slavery beliefs [BBC News]. Published to coincide with Darwin’s 200th birthday and the 150th anniversary of his publication of On the Origin of Species this year, the book is likely to stir up a new debate over Darwin’s motives.
Many members of Darwin’s extended family were deeply devoted to the abolitionist cause, including his grandfather, Josiah Wedgwood, who founded a chinaware company and produced cameos distributed by anti-slavery campaigners; the medallions bore the legend “Am I Not a Man and a Brother?” Darwin’s mother and wife were Wedgwoods and anti-slavery was what Darwin called a “sacred cause”. He was taught to see the oppressed black as a “brother”. This explains why, when he went to Edinburgh University at 16, he could apprentice himself to a freed Guyanese slave to learn the art of bird preservation without thinking it [beneath his dignity] [Times Online]. Darwin later described that former slave as one of his intimate friends.
On the slopes of the Wolf volcano at the northern tip of one of the Galapagos Islands prowls a pink iguana, which until recently had entirely escaped the notice of the island’s visitors–including the eagle-eyed Charles Darwin. But now researchers have spotted the rosy reptile and declared it a new species, which diverged from the Galapagos’s other land iguana species about 5.7 million years ago. Says lead researcher Gabriele Gentile: “What’s surprising is that a new species of megafauna, like a large lizard, may still be [found] in a well-studied archipelago” [National Geographic News].
The creature was first noticed by park rangers on the island of Isabela in 1986, but researchers only began to study the animal in the last few years. A genetic analysis revealed that the pink iguana was quite distinct from the two known land iguana species, but the date of their genetic divergence poses a puzzle. “At 5.7 million years ago, all of the western islands of the archipelago did not exist,” said Gabriele Gentile…. “That’s a conundrum, because it’s now only inhabiting one part of Isabela that formed less than half a million years ago” [BBC News]. In fact, even the oldest parts of the current archipelago may be less than five million years old, researchers say. One possible explanation is that volcanoes that are now underwater may have been above the waves millions of years ago, allowing some marine iguanas to clamber onto those shores and begin evolving.
Poor Lonesome George: Although he may have found a mate, researchers say he is still being denied the joys of fatherhood. George is thought to be the last representative of a tortoise subspecies from the Galapagos Island of Pinta, and researchers rejoiced this summer when he appeared to father a batch of eggs. But earlier this week a spokesperson for the Galapagos National Park announced that 80 percent of the eggs do not appear to be viable.
The excitement began this summer when two female tortoises exhibited surprising behavior. The females, who have shared George’s enclosure at the Charles Darwin Research Station on the central island of Santa Cruz for almost 20 years, are of a different but closely related species. After decades of reproductive reticence, they stunned scientists during the summer by building nests and filling them with eggs for the first time [Nature News]. Researchers quickly removed the 16 eggs from the nests and installed them in an artificial incubator, although three of those eggs were thought to have already deteriorated.
Researchers may be able to recreate a species of giant tortoise that went extinct from the Galapagos Islands with a program of careful breeding. The new possibility hinges on the discovery that a species of giant tortoise living on the biggest island, Isabela, is very similar genetically to the extinct species, Geochelone elephantopus, which vanished from the island Floreana over a hundred years ago.
By mating Isabela tortoises that are most genetically similar to G. elephantopus, selecting the offspring that are most similar and mating those, through successive generations the species’ genetic makeup may be largely restored [The New York Times]. Says lead researcher Gisella Caccone: “We might need three or four generations to do this…. But in theory it could be done, and I think it’s pretty exciting to bring back from the dead a genome that we thought was gone” [BBC News].