Courtesy Fancy Horse (underwater background)The genome of the coelacanth, the world's best known living fossil, has been sequenced by an international team of researchers and is revealing something scientists already suspected: that the primitive-looking fish has evolved more slowly than most other organisms. The coelacanth is related to the lungfish and several extinct Devonian fish species that are considered precursors to land dwelling tetrapods. Kerstin Lindblad-Toh is senior author of the study which appeared recently in the science journal Nature.
"We often talk about how species have changed over time, but there are still a few places on Earth where organisms don't have to change, and this is one of them," Lindblad-Toh said. "Coelacanths are likely very specialized to such a specific, non-changing, extreme environment -- it is ideally suited to the deep sea just the way it is."
Lindblad-Toh is scientific director of the Broad Institute's vertebrate genome biology group in Cambridge, Massachusetts, which did the genome research. The institute is linked to both MIT and Harvard.
The genetic map, which involved sequencing some 3 billion letters of DNA, also showed (via RNA content) that tetrapods - four-legged land dwelling animals - though related to both coelacanths and lungfish, are more closely related to lungfish and followed that line rather than that of the coelacanth. We humans also branched off that same line. The genome of a lungfish is composed of over 100 billion DNA letters, making it a much more difficult task to sequence, so for the time being, the coelacanth's DNA makes for a reasonable alternative for study.
"This is just the beginning of many analyses on what the coelacanth can teach us about the emergence of land vertebrates, including humans, and, combined with modern empirical approaches, can lend insights into the mechanisms that have contributed to major evolutionary innovations," said professor Chris Amemiya at the University of Washington, and the paper's co-author.
Courtesy photo by Haplochromis via Wikipedia Creative CommonsWhen Louis Agassiz named the first fossil coelacanth back in 1836, the Swiss paleontologist probably never imagined that a nearly identical descendent of the primitively constructed Devonian-aged fish would one day be found still inhabiting the world's oceans. The coelacanth was thought to have gone extinct along with the non-avian dinosaurs at the end of the Cretaceous period. None have been found in the fossil record after that time, but two extant species are known today. The first specimen Latimeria chalumnae was netted off the coast of South Africa in 1938, near the Chalumnae river and retrieved by East London Museum curator Marjorie Courtenay-Latimer who discovered what she called "the most beautiful fish I'd ever seen" in the catch of local fisherman, Henrik Goosen. Since then several more coelacanths have been caught, including the Indonesian species, Latimeria menadoensis, from the Indian Ocean.
The remarkable prehistoric throw-back, sometimes referred to as "old four legs" because of its leg-like fins, hasn't changed much in its 350 million year history. A member of the clade of lobe-finned fishes called Sarcopterygii, coelacanths retain primitive characteristics such a notochord, a hollow fluid-filled tube made of cartilage that underlies the spine over the length of its body. In all other vertebrates, the notochord is an anatomical structure that appears briefly only during the embryonic stage but not in adults. Not so with the coelacanth. It also possesses, primitive shark-like intestines, a linear heart, and tightly-woven armor-like scales (known as cosmoid) that are only found on extinct species of fish. The coelacanth's brain case contains only 1.5 percent gray matter - the other 98.5 percent of space is filled with fat. The other end of the coelacanth body begins to taper before expanding into a strange, three-lobed tail. Its most notable features are its lobed pectoral and pelvic fins that are structured with bones that look like toes, and move in an alternating tetrapod manner. An electroreceptive rostal organ located in its snout is used to detect prey, and the coelacanth is the only living animal that can unhinge a section of the its cranium to increase the gape of its mouth, enabling it to consume larger prey.
The blue or brown, white-speckled coelacanths prefer deep-water environments, and can reach six and a half feet in length and weigh upwards to 175 pounds. For some reason no living coelacanth has managed to survive more than a single day in captivity. With a dwindling population estimated at only 500-1000 individuals, the coelacanth was declared an endangered species in 1989.
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We've all seen them, those great B-films where a giant, vicious monster from under the sea, or invaders from outer space arrive to cause mayhem across our cities and generally mess up our way of life. In the end, it seems no matter who or what it was that was attacking us, be it Mothra, Godzilla, or some race of belligerent extra-terrestrials, we could always count on the military to save our collective behind.
Unfortunately, with mosquitoes, that might now be the case anymore.
Scientists are reporting that Deet, one of the most widely used active ingredients in insect repellents, loses its effectiveness against mosquitoes shortly after those ubiquitous, blood-seeking winged vermin are first exposed to it.
Deet - the common name for N,N-diethyl-meta-toluamide - was developed by the US Army after the Second World War to help combat insects during jungle warfare. It was used extensively in the Korean and Vietnam wars, but mosquitoes seem to be able to adapt quickly to it.
"Mosquitoes are very good at evolving very very quickly", said Dr. James Logan of the London School of Hygiene and Tropical Medicine and co-author of the study. "There is something about being exposed to the chemical that first time that changes their olfactory system - changes their sense of smell - and their ability to smell Deet, which makes it less effective."
So what I want to know is where does that leave us here in Minnesota where the mosquito constantly competes with the Common Loon for the title of State Bird? Maybe it's time to start digging the bunker in the backyard.
Courtesy wintersixfourZombies are all the rage these days, and not just on cable TV shows or at pub crawls.
The impacted bees get their name for their changing behaviors once they host the parasitic flies that cause the trouble. While most bees spend their nights nestled snuggling in a comb, these "zombie bees" actually go out flying in very erratic patterns. Like many other night bugs, the zombie bees fly to light and usually die quite soon.
What's really at play is that the tiny parasitic flies plant eggs into the host bee. Those eggs grow into maggots that eat the inside of the host bee that ultimately cause its demise.
Evidence of zombie bees was first found in 2008 near Sacramento, Calif., and beekeepers around the west coast have seeing the spread of the problem in the years since.
Researchers are trying to figure out if this parasite problem is a factor in the bee population declines that have been going on nationwide. One researcher has set up a website – ZombeeWatch.org – to allow amateur beekeepers to share information about zombie bees they are finding around their hives. It is also looking for people who want to step forward to be "zombee hunters."
There has been one isolated report of zombie bees in South Dakota. So far, two investigations in Minnesota have turned up no evidence of zombie bees.
Courtesy NASA / JPL-Caltech / Dr. Philip Bart, LSURecent investigations into microfossils show that Antarctica hasn’t been quite the icebox scientists have imagined it to be over the past 34 million years. Pollen and leaf wax samples from Miocene-aged sediments indicate the continent has experienced some periods of warming since the beginning of the most recent glacial period. The core samples studied came from ocean sediments collected near Antarctica, and particulates found in the samples indicate more rain fell on the ice-covered continent during the Middle Miocene epoch (15.5 – 20 million years ago) than previously thought, enough rain to spur the growth of forests of small, stunted trees.
Paleoclimatologist and organic geochemist Sarah Feakins of the University of Southern California and her colleagues analyzed core samples taken from between 144 and 1,100 meters beneath the ocean floor – levels dating back to the Middle Miocene. Spikes of concentrated amounts of pollens and leaf wax appeared in two periods – one about 16.4 million years ago, and another about 15.7 million years ago. The warm periods were relatively short, each lasting less than 30,000 years.
In a previous study, palynologist Sophie Warny of Louisiana State University had first described the pollen and leaf wax spikes found in the core samples, and she and Feakins eventually teamed up for the recent study. The team determined the particle spikes didn’t arise from the leaf wax and pollen blowing in from elsewhere but rather came from two species of trees that once lined the shores of Antarctica. The two species, podocarp conifer and southern beech wouldn’t have grown very tall – maybe knee-high – and neither spreads their pollen over wide areas. Had the pollens blown in from elsewhere - say South America or New Zealand - there were would have been more species in the mix.
Using a mass spectrometer, Feakins and NASA researchers analyzed the ratio of hydrogen to deuterium atoms in the wax molecules which indicated the temperature at the Antarctica location during the two warm periods was about 7 degrees Celsius during the summer. Today, summer temperatures in the same region are about –4 °C. The average global temperature at the time was about 3 °C higher than it is today. As the overall global temperature changes a relatively greater change in polar temperature isn't unexpected due to a process called polar amplification.
The data from Feakins and Warny’s study, which appeared in Nature Geoscience, adds to growing concerns over the sensitivity of Earth’s climatic and hydrological systems. At the moment, no trees line the shores of Antarctica, but current levels of carbon dioxide (393 parts per million) are not far off those thought to have existed during the Middle Miocene’s warm periods (400-600 parts per million) when forests did exist on the margins of the icy continent. This could indicate that even small changes in carbon dioxide levels can are capable of creating big changes in climate.
Courtesy Public domain via Wikipedia This cool evolution timeline is really fascinating and fun to mess around with. I'm guessing Charles Darwin would agree it's a vast improvement over the one that appeared in Punch Almanac in1882 when he was still alive (see image at right). This new one was created by John Kyrk, a biology-trained artist in San Francisco in collaboration with Dr. Uzay Sezen, a plant biologist from the University of Georgia. The timeline is available in several languages and would be very useful in a classroom setting when studying evolution and paleontology.
The site is interactive and follows the evolution of our universe from the Big Bang to the present. You start it by clicking and sliding the red pyramid on the right. As you scroll across the timeline, various events in the history of the Universe, Solar System and ultimately, the Earth show up on the screen. All along, links also appear that either explain concepts or show examples of them. In the upper left hand corner is a menu linking you to several corollary Flash animations by Kyrk explaining cell biology and how RNA, DNA, cells, water, and other basic elements of life (including viruses) operate. Kyrk thinks animated illustrations are very useful in teaching and remembering ideas and concepts.
All the phases of Earth’s formation and development are covered in the evolution timeline, including the Late Heavy Bombardment, Snowball Earth, Cambrian Explosion, stromatolites, photosynthesis and iron formation. Once life begins to rise up, your computer screen will run amok with Earth’s diverse species populations from the one-celled animals, trilobites and fish to amphibians, reptiles, dinosaurs and mammals – the whole shooting match. All the major extinction events are shown, too.
The site also contains a link to this YouTube video version of someone else working the timeline so you can just sit back and watch how it happens, But I recommend working the interactive page yourself. A lot more happens and is available than the video allows you to see. Note that you’ll need Flash for it to run on your computer.
I wonder how Darwin would have reacted if he were able to see his theory illustrated in this way?
Courtesy National Center for Ecological Analysis and SynthesisOne of the great extinctions in Earth history occurred 252 million years ago when about 95 percent of all marine species went extinct. The cause or causes of the Great Dying have long been a subject of much scientific interest.
Now careful analyses of fossils by scientists at Stanford and the University of California, Santa Crux offer evidence that marine animals throughout the ocean died from a combination of factors – a lack of dissolved oxygen, increased ocean acidity and higher water temperatures. What happened to so dramatically stress marine life everywhere?
Geochemical and fossil evidence points to a dramatic rise in the concentration of carbon dioxide in the atmosphere, which in caused a rapid warming of the planet and resulted in large amounts of carbon dioxide dissolving into the ocean and reacting with water to produce carbonic acid, increasing ocean acidity. The top candidate for all this carbon dioxide? – huge volcanic eruptions over thousands of years in what is now northern Russia.
Why should the Great Dying be of more than just academic interest? Humans currently release far more carbon dioxide into the atmosphere than volcanoes and we are releasing carbon dioxide into the atmosphere at a rate that greatly exceeds that believed to have occurred 252 million years ago. The future of Earth’s oceans will be determined by human decision making, either by default or by design. What do we want our future ocean to be?
Courtesy Photo by Zang Hailong (via Nature)A huge one-and-a-half ton theropod discovered recently in China is further shaking up our old ideas of dinosaurs being oversized scaly lizards. The fossilized remains of Yutyrannus huali, a 130 million year-old tyrannosaur uncovered in the Liaoning fossil beds show evidence of a fuzzy coating of feathers on several areas, e.g. the tail, hip, foot, neck and arm. Yutyrannus huali is a distant relative of Tyrannosaurus rex(there is some contention about this) which didn’t evolve until much later in the Cretaceous period. Evidence of feathers has been found on smaller dinosaurs including the basal tyrannosauroid Dilong but these are the first clues that larger dinosaurs had feathers. Three nearly complete and well-articulated skeletons of Y. huali - an adult and two juveniles were found in the Lower Cretaceous Yixian Formation of Liaoning Province in northeast China. The adult is quite large, being nearly 30 feet in length and estimated to have weighed in life around 3000 pounds! The two juveniles weighed around 1200 pounds. All show evidence of having filamentous feather. Large animals today, such as elephants, rhinos, and hippos are somewhat hairless and tend not to need insulation for retaining heat because of their size and the ratio of surface area of skin to their masses. Whether Yutyrannus huali’s well-known descendent Tyrannosaurus rex had any plumage remains a mystery. T. rex was six times as massive as its ancestor, and arrived on the scene 60 million years later in the Late Cretaceous when the climate was warmer. But all it takes to change that is some new fossil to come to light. Generally, it’s thought that feathers first appeared as a means of insulation, species identification, or for attracting mates long before they evolved for use in flight. Today, birds are considered the descendents of small theropods dinosaurs called dromeosaurids. The discovery of Yutyrannus huali adds new clues and additional mystery to our conception of how dinosaurs appeared in life. The new study by Chinese vertebrate paleontologist Xu Xing and his co-researchers appears in the science journal Nature.
Iridescence is usually a vanity thing in nature; birds and butterflies, for instance, use it to attract mates. This is
Courtesy Killer18the type of thing that would be completely lost on a blind mole...or is it? In the case of the golden mole, iridescence is very much a part of its appearance, but according to a new study about the structure of hair, this iridescence takes on a more functional role. The nano-sized structures on the flattened, paddle-shaped hairs not only give the moles a lovely sheen (for animals that can actually see them), but may also help to repel water and streamline the moles as they move through the sand. This is definitely a case of function over form.
Yesterday, I had the pleasure of attending Environmental Initiative's 2012 Legislative Preview, part of their Policy Forum series.
Basically, a bipartisan group of legislators discussed their environmental priorities with a diverse audience of public, private and nonprofit representatives for the purpose of providing
"a valuable first look at the most pressing environmental issues facing the state in anticipation of the upcoming legislative session."
Courtesy State of Michigan
The biggest surprise to yours truly was the prevalence of carp among the discussion. Asian carp, AIS (aquatic invasive species), etc., etc.. Everyone appeared in agreement regarding the threat posed by carp, so the real question is what do we do about their impending invasion?
One repeated suggestion was to fund more research, specifically at the University of Minnesota. This is probably an important step towards defending our state waterways, and I think this story helps illustrate why:
"As yet, no technology can stop these downstream migrations; neither grates nor dangerous, expensive electrical barriers do the job.
But a wall of cheap, harmless bubbles just might—at least well enough to have a significant benefit."
Researchers at the U of MN have discovered that bubble barriers may deter 70-80% of carp migration. It's not the visual affect of the bubbles that prevents all but the most daring carp from penetrating the barrier, rather the noise -- equivalent to what you or I would experience standing about three feet from a jackhammer.
The bubble barrier has currently only been tested on common carp, but researchers involved in the experiment want to test the technology on Asian carp next.
In addition to the bubble barrier, U of M researchers are investigating whether Asian carp pheromones can be used to lure them into traps.
In this video renowned paleontologists Bob Bakker and Peter Larson visit the CK Preparations lab in Montana to examine the incredible discovery by Clayton (“Dino Cowboy”) Phipps of the remains of a tyrannosaurid and some sort of ceratopsian dinosaur preserved together (and touching) in a single block of rock from the Hell Creek Formation. Both skeletons are articulated, nearly 100 percent intact, and in a wonderful state of preservation. Teeth matching those remaining in the tyrannosaurid jaws are preserved imbedded in the ceratopsian skeleton. The predator’s skull, which is speculated to be that of a Nanotyrannus, shows signs of being kicked in. Early analysis of the geology of the matrix encasing the find suggests that the two battling dinosaurs may have gotten trapped in mire or overcome by a sudden environmental catastrophe, like a cave-in. Was this a unique moment frozen in time of a battle between a predator and its prey? Do the two "combatants" represent entirely new genera of dinosaurs? These questions require further study and preparation of this very unusual fossil.