Blogs / 80beats

Researchers had high hopes for Cedric the Tasmanian devil: They believed he was the first member of the species to be immune to the deadly facial cancer that is rapidly devastating devil populations. Now, in a major setback, Cedric has grown two small tumors and researchers are back to square one. Many experts believe that the infectious cancer, called devil facial tumor disease, could drive the species to extinction within 20 years if it goes unchecked.

Cedric was captured in western Tasmania last year, along with his half-brother, Clinky. Both were injected with dead tumours by scientists. Clinky produced no antibodies, but Cedric did, and appeared to have built-in defences against the illness [BBC News]. However, the next step yielded worse results. Researchers injected two live strains of the disease into Cedric’s cheek in an attempt to prove his immunity, but two small tumors grew at the injection sites. The tumors were surgically removed last week, and while Cedric is expected to make a full recovery, his love life has been put on hold by the researchers. They were trying to get him to mate so he would pass on his genes. Now they’re unsure if Cedric is naturally immune to the disease [ABC News].

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An asteroid that crashed into the earth 65 million years ago may not have been the cause of the dinosaurs‘ extinction, a group of researchers are arguing. Instead, that impact may have been just a prelude to the main event, when a wave of volcanic eruptions spewed out massive clouds of sulfur dioxide, clouding the air and bringing showers of acid rain. The researchers are basing their theory on studies of an area in India called the Deccan Traps, which was convulsed with volcanic activity around 65 million years ago. At least four waves of massive eruptions spread successive sheets of thick basalt across the land for more than 500 miles, and they piled into a plateau more than 11,000 feet high over thousands of years [San Francisco Chronicle].

The new research on the Deccan Traps volcanoes, announced at the ongoing meeting of the American Geophysical Union, are the first major challenge to the asteroid theory that has dominated dinosaur extinction studies for three decades. That theory posits that a six-mile-wide asteroid slammed into Mexico’s Yucatan peninsula, creating the Chicxulub crater and cooling the climate so drastically that the majority of life forms went extinct in what’s known as the Cretaceous-Tertiary (or K-T) extinction. But geologist Gerta Keller and her colleagues argue that the impact occurred well before the massive die-offs began. By examining sediment layers, the team found that the crater impact appears to have occurred about 300,000 years before the K-T boundary, with virtually no effects to biota. “There is essentially no extinction associated with the impact,” Keller said [LiveScience].

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A cooling climate, not human hunters, were at fault for the extinction of the prehistoric cave bear (Ursus spelaeus), according to a new study. Researchers examining cave bear remains now say the giant vegetarians died from starvation and much earlier than previously thought. “The disappearance of the cave bear around 27,500 years ago was probably due to the significant decline in quantity and quality of plant food, which in turn was the result of marked climatic cooling,” [Telegraph] said researcher Anthony J. Stuart.

Previous radiocarbon dating of cave bear remains incorrectly placed their apocalypse at 14,000 years ago because some of the remains were actually those of brown bears, still alive today, that were mistakenly identified. The new study excludes previous errors and includes new data taken from remains found in ancient hibernation sites in the Alps. The new extinction date, 27,800 years ago, coincides with a period of significant climate change, known as the Last Glacial Maximum [or Ice Age], when a marked cooling in temperature resulted in a reduction or total loss of the vegetation that the cave bears ate (today’s brown bears are omnivores) [LiveScience.com].

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The genome of the woolly mammoth is halfway sequenced and science-fiction fanatics are once again talking about resurrecting extinct species–except this time, the scientists are talking too. Researchers at Pennsylvania State University extracted DNA from the hair of two woolly mammoths found in the permafrost of Siberia; one lived about 20,000 years ago, the other about 60,000 years ago. Reporting in Nature [subscription required], the researchers say they have already sequenced more than three billion base pairs of the mammoth genome, and they say there should be no technical obstacles to sequencing the complete genome. “It’s a technical breakthrough,” says ancient-DNA expert Hendrik N. Poinar [Scientific American].

Access to clumps of preserved mammoth hair was essential to the researchers’ success. The tough keratin that makes up the hair encased the mammoth’s DNA and separated it from any alien fragments, keeping these samples more pure [New Scientist]. Horns and feathers are also made of keratin, broadening the prospects of sequencing other extinct species from museum specimens.

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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.

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In a big step forward for cloning research, scientists have produced healthy clones of mice that were dead and frozen for 16 years. Researchers say the new technique could allow conservationists to freeze tissue from endangered species, which could then be used to produce clones if those species become extinct. The finding also raises hopes of one day being able to resurrect extinct animals frozen in permafrost, such as the woolly mammoth, says [lead researcher] Teruhiko Wakayama…. “It would be very difficult, but our work suggests that it is no longer science fiction,” he says [New Scientist].

Researchers have previously produced clones from frozen animal tissue, but only from specimens that were preserved with special chemicals to protect cells from damage during the deep freeze. In this study, published in the Proceedings of the National Academy of Sciences [subscription required], no such special precautions were taken when the mice were stowed in a freezer 16 years ago. Many zoos are not in a position to collect cells and freeze them in such a way as to preserve their viability, says [cloning expert] Robert Lanza … but they can put a dead animal “in a plastic bag and throw it in the freezer”, he adds. “With a kitchen freezer you could store the genetic diversity of every panda in existence” [New Scientist].

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Several rare varieties of staghorn coral have begun mating across species lines and are creating surprisingly robust hybrids, according to a new study; researchers believe the unusual step is an effort to adapt to changing ocean conditions and avoid extinction. The findings are an unexpected piece of promising news about coral reefs, which usually make the headlines for their potential fate as one of the first victims of global warming.

Coral reefs around the world are under pressure from pollution and gradually warming oceans, and researchers have worried that rare species are particularly vulnerable to extinction. But in the case of these staghorns, the new study shows that when faced with a shortage of mates of their own kind, these rare corals have cast a wider net and started cross-breeding with other coral species, producing hybrids. “It pushes the boundaries of our traditional understanding of species,” said a researcher, Zoe Richards. “They are being a little promiscuous” [Sydney Morning-Herald].

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Global warming isn’t just a threat to polar bears in the rapidly warming Arctic, a new study says: Species in the tropics are beginning to feel the effects as well, and it will only get worse. Researchers surveyed more than 1,900 species of plants, insects, and fungi in a Costa Rica rainforest and came to the troubling conclusion that if world temperatures continue to rise as predicted over the next 50 years, half of those species will have to move to completely new territory to find an appropriate habitat.

The situation is complicated for tropical species, says lead researcher Robert Colwell; shifting north or south doesn’t bring significantly lower temperatures, so species will have to take up residence at higher altitudes to survive. In the absence of mountainsides to serve as a cool refuge, those plants and insects that cannot face higher temperatures may disappear as it would require migrations of hundreds or even thousands of miles to find a suitable cooler climate—crossing habitats utterly changed by human impacts. “For lowland tropical species whose geographical range lies far from mountains, for example in the middle of the Amazon,” Colwell says, “the prospect for extinction cannot be dismissed” [Scientific American].

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An international group of researchers has issued a dire warning about the state of the world’s wild animals. A new report from the International Union for the Conservation of Nature (IUCN) lists one in four land mammals as endangered, as well as one in three marine mammals. Life on Earth is disappearing fast with man inflicting most of the damage…. On land more species face oblivion because of loss of habitat, hunting and climate change while in the oceans pollution and the side effects of fishing are taking a huge toll [Telegraph].

The new assessment — which took 1,700 experts in 130 countries a total of five years to complete — paints “a bleak picture,” leaders of the project wrote in a paper being published in the journal Science. The overview … covers all 5,487 wild species identified since 1500. It is the most thorough tally of land and marine mammals since 1996 [Washington Post].

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The dinosaurs that held dominion over the Earth in the Jurassic Period didn’t rule the lands because they out-competed every rival, a new study says. Researchers studied fossil evidence from an earlier epoch, the Triassic Period, and say that dinosaurs showed no evidence of being better adapted to their environment than their challengers. “For a long time it was thought that there was something special about the dinosaurs that helped them become more successful during the Triassic, the first 30 million years of their history, but this isn’t true,” said lead author of the study, Steve Brusatte [LiveScience].

Instead they may have just been lucky enough to survive a drastic climate shift when their rivals didn’t. Researchers compared fossils from the 30 million years in the Triassic when dinosaurs coexisted with crurotarsan archosaurs, a group whose only living relative is crocodiles. They found that not only did the groups evolve at the same rate, but the crurotarsans even developed a wider range of body types than dinosaurs, suggesting that the group as a whole was more successful at developing to live in different habitats and ecosystems [Telegraph].

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The last woolly mammoths, who tromped around the Siberian tundra before going extinct about 10,000 years ago, had North American roots, according to a new genetic analysis. Scientists studied DNA from the remains of 160 mammoths from across North America and Eurasia, and determined that the last remaining mammoths were migrants who had come to Siberia via the Bering land bridge, and somehow replaced the endemic population.

Researchers believe that mammoths originally spread from Asia to North America via the land bridge, creating two genetically distinct populations. Now, they’re hypothesizing that some members of the North American group eventually made a return trip and proved hardier survivors than the Siberian group. “For some reason the North American guys went back over and became kings,” says [lead researcher] Hendrik Poinar [New Scientist].

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Dinosaurs—they grow up so fast, especially if they’re trying not to get eaten.

Hypacrosaurus, a duck-billed dinosaur that could reach more than 30 feet in length, was a preferred meal of the Tyrannosaurus Rex. But this prey dinosaur had a trick to keep the species alive—Hypacrosaurus grew to adulthood remarkably quickly, according to a new study in the Proceedings of the Royal Society B [pdf]. The research suggests that it took 10 to 12 years for Hypacrosaurus to become fully grown. Tyrannosaurs, however, reached adulthood after 20 to 30 years, said Drew Lee, a postdoctoral fellow in Ohio University’s College of Osteopathic Medicine who co-authored the paper [Science Daily].

The Hypacrosaurus’ accelerated growth rate allowed it to reach sexual maturity at only two or three years old, giving it the chance to reproduce before predators gobbled it up, according to study co-author Lisa Noelle Cooper. “That’s another added bonus when facing predators—if you can keep reproducing, you’re set, it’s the stuff of evolution,” said Cooper [AFP].

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An ambitious study of all the primates on planet Earth has found that almost half of all species are threatened by extinction because of habitat loss and poaching. The latest Red List of Threatened Species, drawn up by the International Union for Conservation of Nature (IUCN), says that almost 50 per cent of the world’s 634 types of primate may disappear forever [Telegraph].

The findings highlight the multiplying threats facing primates throughout Africa, Asia, and South America, says IUCN official Russell Mittermeier: “Tropical forest destruction has always been the main cause, but now it appears that hunting is just as serious a threat in some areas, even where the habitat is still quite intact. In many places, primates are quite literally being eaten to extinction” [Bloomberg]. The study results were announced at the current International Primatological Society meeting.

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An extinct ancestor of the great white shark had a powerful bite that wouldn’t just put Jaws to shame, according to a new fossil analysis by Australian researchers. The colossal force of Carcharodon megalodon - also known as Big Tooth - made even Tyrannosaurus rex look puny [Telegraph].

In the study, to be published in an upcoming issue of the Journal of Zoology [subscription required], researchers took CT scans of both the skulls of great white sharks and those of the prehistoric megalodon, who swam the oceans about a million and a half years ago. They made computer models of the skulls, and then ran an analysis on the models that engineers use to determine how machinery holds up under stress.

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The Cretaceous period was such a good time for evolution that researchers talk about the “Cretaceous Terrestrial Revolution,” when as an explosion of new plant and animal species appeared. But researchers say that a detailed analysis of dinosaur diversity during this period debunks the prevailing theory that dinosaurs took part in this evolutionary spree; instead, their rapid evolution had taken place millions of years before.

The Cretaceous period, which lasted from 145 million years ago to 65 million years ago… saw the diversification of pollinating insects such as bees, butterflies, and moths. New forms of lizards, crocodiles, and snakes appeared, as did many of the ancestors of modern groups of birds and mammals. The Cretaceous also saw the explosion of angiosperms, or flowering plants [ScienceNOW Daily News]. Some researchers have previously suggested that the wide availability of those flowering plants sparked an evolutionary surge in dinosaurs who fed on the plants, and others who fed on the plant-eaters.

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