Warmer climate accelerates evolution in mammals
in Life Science, Cells, Diversity of Organisms, Heredity, and Biological Populations Change Over Time
Warmer climate boosts evolution: Okay, so iguanas aren't mammals, and I doubt Charles Darwin ever visited Sloppy Joe's in Key West, Florida, but the graphic still illustrates the point.
Courtesy Apollo13Ma (background photo), public domain and Mark RyanA study out of New Zealand says a warmer climate speeds up molecular evolution in mammals. The concept isn’t exactly a new one. Scientists have known that a warmer environment increases the pace of microevolution for other types of life, such as some plants and marine animals, but evidence that it affects mammals – which are warm-blooded (meaning their temperature is regulated internally) – has not been observed before.
Lead researcher, Len Gillman from Auckland University of Technology, said the result of the study was “unexpected”.
""We have previously found a similar result for plant species and other groups have seen it in marine animals. But since these are 'ectotherms' - their body temperature is controlled directly by the environment - everyone assumed that the effect was caused by climate altering their metabolic rate.""
Since DNA can potentially mutate each time a cell divides into two copies of itself, the faster (and more often) these divisions take place, the more chances advantageous mutations will be passed onto subsequent generations, and the faster microevolution takes place.
Gillman and his crew traced and compared small genetic changes in 130 pairs of related species that lived in different latitudes, focusing on a single gene in each pair. They then compared the gene against that of a common ancestor, and were able to determine which of the two mammals’ DNA had mutated (microevolved) more rapidly. The changes were small-scale, but the species living in the more tropical environment showed a faster pace in its level of molecular evolution.
The results of the study appear in Proceedings of the Royal Society B.
LINKS
Discover magazine story
BBC story
More about evolution
Tags : Jane Goodall, the internationally-known chimp researcher, will be making a pair of public appreances at the University of Minnesota on Saturday. Here's a link to the details. Both events are free and open to the public.
So what did you do over the weekend? I guess we all missed these wild times going on in Botswana, Africa. Check out this video of an elephant pool party. I wonder if the Republican National Convention will get this crazy here in St. Paul in September?
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
Photo of Hopi chipmunk by Mdf courtesy Wikipedia Commons.
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Yanoconodon allini: Artist's representation of Yanocondon, a Mesozoic mammal fossil found in China. Courtesy Nicolle Rager Fuller, National Science Foundation.A newly discovered fossil dating back to the time of the dinosaurs presents fresh evidence of the evolution of the mammalian ear.
The small squirrel-like mammal, named Yanoconodon allini, measured about five inches in length, with short limbs and claws, and, in life, would have weighed less than an ounce.
The remains, found in the Yan Mountains of the Hebei Province in China by an international team of American and Chinese scientists, present a mammal unlike any known before. The new creature, which belongs to the group of Mesozoic mammals known as triconodonts, contains an unusually large number (26) of thoracic and lumbar vertebrae for such a small animal. Similar creatures have only 19 or 20 vertebrae. It’s the first Mesozoic mammal found in the fossil-rich deposits located about 180 miles from Beijing.
But the new mammal’s ear structure is what interests scientists most.
Mammals far surpass other vertebrates in their ability to hear. Small bones in the middle the mammalian ear structure, (the hammer, the anvil, the stirrup, and the bony ring for the eardrum), are responsible for this aural sophistication. And while scientists have long recognized that these bony structures evolved from detached segments of the jaw hinge of reptilian ancestors, the new fossil’s well-preserved ear structure provides an intermediate phase in that evolution.
"Now we have a definitive piece of evidence, in a beautifully preserved fossil split on two rock slabs," said Zhe-Xi Luo, a paleontologist at the Carnegie Museum of Natural History in Pittsburg, Pennsylvania. "Yanoconodon clearly shows an intermediate condition in the evolutionary process of how modern mammals acquired their middle ear structure."
Luo and his Chinese collaborators published their discovery in a recent issue of the journal Nature.
"This new fossil offers a rare insight in the evolutionary origin of the mammalian ear structure," added Luo. "Evolution of the ear is important for understanding the origins of key mammalian adaptations."
An acute sense of hearing would have certainly come in handy to the pip-squeak Yanoconodon scurrying among the gigantic dinosaurs that ruled its Mesozoic world 125 million years ago.
"This early mammalian ear from China is a Rosetta-stone type of discovery which reinforces the idea that development of complex body parts can be explained by evolution, using exquisitely preserved fossils," said H. Richard Lane, program director in National Science Foundation’s Division of Earth Sciences, which helped fund the discovery.
LINKS
Livescience.com
Physorg.com
ScienceDaily.com
National Science Foundation
TerraDaily.com
Giant Panda: Courtesy drs2biz
Three new panda cubs were born in China this past week. The new births, brings the total of giant pandas born in captivity up to six for the year. The giant panda is an exotic, endangered species mostly found in China. China considers these pandas a national treasure.
One of the three new panda cubs has created quite the stir. Six-year-old Zhang Ka gave birth to the heaviest cub ever born in captivity after the longest labor period. The new cub weighed in at 218 grams (half a pound). Ordinarily, most cubs weigh between 83 and 190 grams at birth. Zhang Ka was in labor for 34 hours making her labor the longest in panda reproduction history. Reports say both the mother and cub are doing well.
Breeding giant pandas in captivity is a cumbersome task. Female pandas ovulate once a year with a tiny conception window. There is a minute window of 24 to 48 hours where artificial insemination methods are conducted. Overall, there are about 1,000 giant pandas living in the wild and about 140 pandas living in zoos and breeding centers around the world (however most are in China).
Giant Panda: Courtesy Jellyrollhamster
Giant pandas are bear-like in shape with black and white coloration. Their ears, eye patches, legs and shoulder band are black while the rest of their body is white. Giant pandas live in temperate-zone bamboo forests in central China. Scientists are unsure of their life expectancies in the wild but in captivity the giant panda’s lifespan averages more than twenty years.
Just out of curiosity, what names would you pick for the new panda cubs?
Scientists in China have discovered two fossil mammals from the age of dinosaurs. One still had in its stomach the remains of its last meal--a baby dinosaur. The other mammal, the size of a modern dog, is by far the largest mammal known from this period.
These fossils are cool for a bunch of reasons. Complete skeletons are rare, and skeletons with stomach contents preserved are extremely valuable: they tell us who ate who, and how animals related to each other and to their environment.
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