Stories tagged extinction
Man vs. mammoth: Is a face-off like this in our future...again?
Courtesy redskunkScientists are another step closer to making Jurassic Park a reality. Well, not quite Jurassic Park, but certainly Pleistocene Park.
Researchers at Pennsylvania State University have decoded 80 percent of the DNA for the woolly mammoth, an elephant ancestor that went extinct about 10,000 years ago. The results of their study appear in the journal Nature.
The DNA was extracted from actual mammoth hair found preserved in the permafrost of Siberia. Hair encapsulates DNA, providing a purer source of the genetic material than that found in fossil bones that are vulnerable to contamination by bacteria and other creatures involved in decomposition. We covered this in a previous post.
About six million years of evolution separate the wooly mammoth from its modern descendents the Indian and African elephants. And so far they appear genetically to be very similar, although a complete assessment of differences won’t be available until the complete genomes of mammoths and modern elephants are mapped. The data sets for each is comprised of about 4 billion DNA bases.
But even then you don’t have to worry about rogue mammoths running amok on the interstates (have you ever hit a moose? Multiply that experience by about 15). Science is still decades away from cloning an actual specimen – or even a hybrid with a living elephant - from the genetic material. The technology just isn’t there yet. But that’s not the only thing in the way.
"It could be done,” said co-author Stephan Schuster, a biochemistry professor at Penn State. “The question is, just because we might be able to do it one day, should we do it?"
Sounds familiar doesn’t it? The same question was posed by one of the characters in Michael Crichton's book Jurassic Park just before things got really hairy.
SOURCES and LINKS
Penn State's mammoth research page
Live Science story
Previous Buzz story on mammoth cloning
Tags : Contrary to previous reports, the Chinese river dolphin may not yet be extinct. A man claims to have videotaped an animal which may be a member of this critically endangered species.
A Permian anteosaurus: He feels vaguely nervous, and oddly sweaty. (image courtesy of Wikipedia Commons)65 million years ago something very sad happened. Well, it was sad for the dinosaurs, because they all died, but great for us mammals. Here – I’ve written a little play about it:
Scene 1
Dinosaur 1: Hey, have you noticed that there seem to be a lot less of us these days?
Dinosaur 2: What? I don’t know. Why?
Dinosaur 1: Probably just my imagination. Forget about it.
Dinosaur 2: …
Dinosaur 1: Hey, what’s that thing up there?
Dinosaur 2: We call it the sun.
Dinosaur 1: No, that thing – it’s getting bigger, I think.
Dinosaur 2: Oh, not to change the subject, but did you watch Entourage last nigh*
Scene 2
(fiery, dusty chaos)
Scene 3
Rodent-like mammal: Yes!
The End
Anyway, the extinction at the end of the Mesozoic (dinosaur times) was a big deal. But, dramatic as it likely was, it was nothing compared to the extinction at the beginning of the Mesozoic.
Before the dinosaurs existed, the world was ruled by a different kind of animal, the therapsids, or “mammal-like reptiles.” These ranged from little rat like guys to huge fanged and clawed lion-like creatures. About 250 million years ago, though, at the end of the Permian period, there was an extinction event way bigger than the one that would eventually kill all the dinosaurs.
The Permian extinction killed off 90% of all the life on the planet, both on land and in the oceans. Life as we know it just squeaked by complete annihilation. The thing is, scientists still aren’t sure exactly what initiated the extinction. Whatever it was, it caused massive amounts of carbon dioxide, and other greenhouse gases to be released into the atmosphere. The earth would have gotten warmer and warmer, the oceans would have become acidic, and by the time things got back to normal, almost every species on the planet had died out.
Jonathan Payne, a paleobiologist at Stanford, is investigating one of the possible causes of the extinction – a massive volcanic eruption occurring at the end of the Permian. This eruption was the larger than any other that has happened in the last 600 million years, and it spread a four-mile thick sheet of basalt the size of the continental US over Asia. Along with the poisonous gases spewed by the volcano itself, it is believed that the spreading magma may have heated the coal-rich strata near the eruption and released vast amounts of carbon dioxide into the atmosphere. Then, you know, the whole horrible global warming and acidic oceans thing.
Fortunately, for all our CO2 production, we aren’t yet in the Permian extinction league of global warming gases. Still, Payne is comparing contemporary signs of global warming to those leading up to the Permian event. For example, under increasing environmental stresses, coral colonies tend to bleach (as algae leaves the reefs). Researchers will be examining fossilized coral colonies from the end of the Permian to see how they reacted to the changing environment. "We hope to reconcile the short-term processes we observe operating in the modern world with the very long time scales seen in the geologic record," says a researcher in Payne’s lab. If the analogy works, we could better understand the processes of past environmental change, as well as the potential future effects of the environmental changes that are occurring today.
My own theory regarding the Permian extinction largely focuses on the refusal of therapsis to carpool, and their insistence on driving larger vehicles than they really needed (cyconodonts were notorious SUV lovers). Unfortunately, this is extremely difficult to verify in the fossil record. I chalk this up to the poor preservation of pre-Triassic GM products, or, possibly, to the fact that therapsids had adapted to finding (and then losing) well concealed parking spots (they were, after all, much more primitive than us).
Enjoy the photograph: photo by Benchilada on flickr.comAfter an “intensive survey of its natural habitat,” the Yangtze River dolphin has been officially declared extinct. So if, as a person, you ever wanted to see one alive, you’re out of luck. And if, as a Yangtze River dolphin, you ever wanted to be alive, also, you’re out of luck.
From a population of thousands in the 1950s, human activity reduced the Yangtze River, or Baiji, dolphin to just a handful of individuals by the turn of the century. Industrialization of the Yangtze River, unsustainable fishing practices, and mass shipping, rather than direct human persecution, placed the Baiji dolphins under extreme pressure, and now they’re all dead, forever. An article in The Guardian states that this is “the fourth time an entire evolutionary line of mammals has vanished from the face of the Earth since the year 1500.” Quite an achievement.
Bad genes: New findings suggest that wooly mammoths may have been victims more of inbreeding and poor genetics than being over hunted by an emerging human population. (Photo by Torontochub27)A new look at old question, the extinction of wooly mammoths, is leading to a new answer.
It was commonly believed that mammoths died about some 12,000 years ago due to over hunting by the growing human population on the planet. But cutting off of the intercontinental bridge between Asia and North America made have been the main culprit.
Paleontologists from England studying the lifecycle of mammoths now believe that inbreeding and a lack of genetic diversity probably played the biggest role in knocking down mammoth populations. Here’s the quick mammoth timeline:
About 150,000 years ago the huge hairy elephants emerged on the scene in Asia. Some of them migrated across to North America over the land bridge that was open at that time between what is now Russia and Alaska.
Warming of the Earth raised ocean levels and cut off that land bridge, creating two distinct herds of mammoths on the each continent. For a brief time around 100,000 years ago, that land bridge came back, and the herds were able to intermingle again, but rising oceans again cut off the two groups.
With fewer genetic improvement options with the limited size of the herds, the mammoths weren’t able to adapt as quickly when another Ice Age hit some 20,000 years ago. They were able to hang on for another 8,000 years or so before becoming extinct.
Mammal ancestors bided their time
in Life Science, Diversity of Organisms, and Biological Populations Change Over Time
Modern mammals waited for the right time to diversify: Photo of Hopi chipmunk by Mdf courtesy Wikipedia Commons.Results from a new study of mammalian diversity and origins show that most species of mammals alive today waited several millions of years after dinosaurs died out to diversify and take over the world left by their reptilian predecessors.
The conclusion comes from an international research team studying the evolutionary connections between some 4,500 species of mammals. In the process the researchers also developed a “supertree” of mammal relationships. Supertrees are created using numerous smaller studies to summarize the evolutionary history of a large group of organisms.
Some mammals did flourish in the bio vacuum created by the Mass Extinction Event (MEE) that took place at the end of the Cretaceous 65 million years ago - credited to a large asteroid colliding with the Earth - but most of those mammals later became extinct themselves. The ancestors of mammals alive today, including rodents, hoofed animals, primates and humans, existed some 20 million years before the dinosaurs’ demise, but appear to have waited in the shadows before diversifying and expanding.
"Our research has shown that for the first 10 or 15 million years after the dinosaurs were wiped out, present day mammals kept a very low profile, while these other types of mammals were running the show,” said professor Andy Purvis of Imperial College London’s Division of Biology, one of the study’s leaders.
“It looks like a later bout of 'global warming' may have kick-started today's diversity – not the death of the dinosaurs,” he added.
The diversification took place in the Eocene Period and seems to coincide with what is known as the Paleocene-Eocene thermal maximum, a time of peaking global temperatures during the Cenozoic era. But whether the high temperatures caused of biological expansion is not known.
The findings not only counter the widely held idea that ancestors of modern mammals evolved and spread quickly to fill the void left by the mass extinctions of dinosaurs, but also add invaluable insight into other aspects of mammalian evolution.
"Not only does this research show that the extinction of the dinosaurs did not cause the evolution of modern-day mammals, it also provides us with a wealth of other information,” said Dr. Kate Jones from the Zoological Society of London. “Vitally, scientists will be able to use the research to look into the future and identify species that will be at risk of extinction. The benefit to global conservation will be incalculable.”
The research appeared in the journal Nature.
STORY IN MINNEAPOLIS STAR TRIBUNE
MORE ON THE CRETACEOUS
MORE ON THE EOCENE PERIOD
MORE ON MASS EXTINCTIONS
MORE ON MAMMALS
MORE ON DINOSAURS
Waterbirds worldwide are in decline.: Long-billed curlew. Photo US Fish & Wildlife Service
Scientists report that over 40% of the world’s waterbirds are declining in population. The problem is most severe in Asia, though all continents are suffering losses.
The problem is habitat. Some of the richest ecosystems are “edge habitats,” where one type of environment meets another – like, where the sea meets the shore. However, a whopping 2/3rds of the world’s human population lives near the sea shore. As our population grows, more of this habitat is developed for human use, leaving less for birds and other wildlife.
Chinese river dolphin: extinct?
An international team of scientists recently spent six weeks on China's Yangtze River looking for the endangered river dolphin. They were unable to find any, leading some to believe the animal has been driven to extinction.
The 8-foot-long mammal has lived in China's longest river for 20 million years. But massive increases in fishing, shipping and development have pushed the creature to the brink. The last confirmed sighting occurred in 2004, and the last captive dolphin died in 2002.
By definition, scientists don't consider an animal extinct until 50 years after the last sighting in the wild. And the recent survey focused on the river's main channel - it's possible some dolphins may yet hang on in the tributaries. But even if they do, it's unlikely the population can ever recover.
I'm recommending this New York Times article about turtles and their amazing abilities to withstand adversity. They can go without food and water for months at a time, their armored bodies can withstand the impact of a stampeding wildebeast, and they're among the longest-living creatures on Earth. And they don't succumb to old age: if they didn't get eaten, smashed by cars, or pick up diseases, they just might live indefinitely. But for all that, at least half of all turtle species are in trouble, and some of them may be extinct within the next decade.
Earth wobbles impact extinctions
in Earth and Space Science, Life Science, and Earth Structure and Processes
Wobbly planet Earth: Photo courtesy NASA.
The extinction of rodents and other mammals have been linked to variations in the Earth’s tilt and orbit, according to new research published in the journal Nature.
Dutch scientists studying 22 million year old rodent fossils in central Spain found that the rise and fall of the mammal species correlated with cooling periods due to changes in the Earth’s behavior. Rodents offer one of the best fossil mammal records and are excellent indicators of seasonal changes because of their short life spans.
"Extinctions in rodent species occur in pulses which are spaced by intervals controlled by astronomical variations and their effects on climate change," Dr Jan van Dam, of the Utrecht University in the Netherlands, said.
The researchers discovered two cycles associated with changes in climate, habitat and food availability are linked to the disappearance of rodent species. One cycle, which lasts 2.4 million years, is linked to variations in the Earth’s orbit. The other 1.2 million year cycle is related to changes in the tilt of the Earth’s axis. Both cycles would cool the Earth, allowing the expansion of ice sheets and causing species to adapt or die out.
Right now Earth is in a relatively circular orbit and about 700,000 years away from the next period of axis stability.
"The environment is responsible to what happens to species," said Van Dam. "Biological factors are secondary, according to our results."
However, Larry Ciupik, an astronomer at Chicago’s Adler Planetarium says volcanic activities, plate tectonics and the amount of carbon dioxide in the atmosphere also contribute to species turnover.
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