 |
Back to the main page
Archives Of Animal Science Blog
Subscribe To Animal Science Blog RSS Feed
|
Filling the Evolutionary Gap Between Fish and Land Animals
The new species has a skull, neck, ribs, and parts of a fin that resemble the earliest limbed animals, called tetrapods. But the creature also has fins and scales like a fish. "This animal is both fish and tetrapod. We jokingly call it a fishapod," said Neil Shubin of the University of Chicago. He and paleontologists from the Academy of Natural Sciences in Philadelphia, the University of Chicago, and Harvard University conducted the research. They report the finding in two papers published this week in the journal Nature. "Paleontologists have known that animals first appeared on land in the Devonian Period," said Richard Lane, program director in the National Science Foundation (NSF)'s division of earth sciences, which funded the research. "To reach this evolutionary milestone, a skeletal progression from fish to land-roaming tetrapods would have been needed. Now we have new evidence of that progression". The back of the animal's skull, neck, ribs and fins "are particularly tetrapod-like while the snout, lower jaws, and scale-cover are similar to those seen in closely related fish," Shubin said. The animal was a predator with sharp teeth, a crocodile-like head and a flattened body......... Posted by: Kelly Permalink Source Scent Of A Woman Spider
Female Australian redback spider eating male spider, Image: Ken Jones, UTSC
Not the ideal honeymoon, perhaps. But redback males, who get only one mating opportunity - an uncommon occurrence in nature - have a few tricks up their (eight) sleeves. A new study by scientists at the University of Toronto at Scarborough has identified developmental adaptations in male Australian redback spiders (Latrodectus hasselti) that give these guys an edge in their deadly dating game. The study in the April 4 issue of Current Biology reports that males develop faster based on the population density of males and females around them - the first time such a phenomenon has been shown in any animal. "It shows that males are really tracking the selection pressures that they're facing in an environment - they're aware of male density and the amount of competition they're going to be facing," says Michael Kasumovic, a PhD candidate in the UTSC laboratory of Professor Maydianne Andrade. "It's the first time that it's been shown that males are actually changing their development in response to both sexual and natural selection"......... Posted by: Kelly Permalink Source Hummingbirds
The color on a hummingbird isn't caused by pigment in their feathers. Instead, the top layer of a feather is covered with special cells that break up light. As the birds hover and dive, light strikes the cells in their feathers at just the right angle and suddenly you see a flash of brilliant color-a flying jewel!. Did you know that hummingbirds are only found in the South, Central and Northern Americas? There are no hummingbirds in Europe, Asia, Africa or Hawaii. There have been fossils of hummingbirds found in Gera number of, but why these birds became extinct in the eastern hemisphere isn't known. There are 16 species of hummingbirds that breed in North America, mostly in the western and southwestern regions of the US......... Posted by: Kelly Permalink Source Bird Flu Hits Salmon
The surge is attributed to the general lack of beef and pork on the market coupled with the bird flu and the subsequent drop in poultry's popularity. Wholesale prices for salmon fish (trout, salmon and hunchback salmon) grew the most. Salmon climbed from 155 rbl/kg in mid.-February to 200 rbl/kg today. The hunchback salmon stepped up from the recent 40 rbl/kg to 70 rbl/kg. "The fish prices have never soared so high in Russia, it is the record level," said Ledova President Nadezhda Kopytina. The surge roots in a mixture of reasons. The Russian Federal Service for Phytosanitary and Veterinary Supervision, Rosselkhoznadzor, banned deliveries of chilled salmon and trout of Norway starting from 2006, trimming the weekly shipment of 600 tons to 700 tons of frozen and chilled salmon to roughly 500 tons of frozen salmon exclusively......... Posted by: Kelly Permalink Source The Wildlife-Human Connection
The book is available for download in Adobe pdf format. By downloading and printing each of these files, you can reproduce the entire Circular 1285. You will need to have Adobe Acrobat Reader installed on your system to read pdf files......... Posted by: Kelly Permalink Source Freshwater Copepod May Be Several Species
Grace Wyngaard, a biologist at James Madison University in Harrisonburg, Va., and his colleagues Andrey Grishanin of the Russian Academy of Sciences, Ellen Rasch of East Tennessee State University and Stanley Dodson of the University of Wisconsin-Madison published their study in the current issue of the journal Evolution. "The process of forming new species has been cited as one of the most important research topics in biology," said Sam Scheiner, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research. "This study provides critical evidence that the ways species form and evolve are more complicated than we had previously understood". Copepods, microscopic crustaceans that inhabit lakes, ponds, rivers and ditches, serve as the main diet for a number of fish. "Some identically appearing forms collected from the same pond cannot mate and produce young, thus defining them as different species," said Wyngaard. "By following the parents and offspring of these plankton in the laboratory, we discovered that they reorganize their DNA dramatically from one generation to the next"......... Posted by: Kelly Permalink Source Canadian Prairies Facing Water Crisis
"The western prairies are worse than other areas of Canada," said Schindler, co-author of a paper reported in the journal "Proceedings of National Academy of Sciences," early online edition. "One of the referees on this paper said, 'wow, this is like looking out the window of a locomotive 10 seconds before the train crashes.' It is a very dire situation". Eventhough most global studies rank Canada among the top five countries in terms of per-capita water supply, those rankings can be deceptive, argue Schindler and Dr. Bill Donahue, who co-authored the paper. Canada's western prairie provinces (WPP), for example, have an area of 2 million kms that lie in the rain shadow of the Rocky Mountains and as a result, are the driest large area of southern Canada. Little research has been done on the cumulative effects of climate warming, drought and human activity on water shortages. Schindler and Donahue found that the biggest threat was a combined one, made up of several ingredients. First, there is now considerable evidence that the 20th century, when settlers arrived, was the wettest century for at least a couple of millenia. What we think of as normal was not normal in the long-term. "Most earlier centuries had one or more prolonged droughts, some of 10-40 years," said Schindler. "So we should probably not expect a second wet century in a row"......... Posted by: Kelly Permalink Source 57 Billion Dollar Service By Insects
"Most insects tirelessly perform functions that improve our environment and lives in ways that researchers are only beginning to understand," Losey says. "Don't let the insects' small stature fool you - these minute marvels provide valuable services." The study found that native insects are food for wildlife that supports a $50 billion recreation industry, provide more than $4.5 billion in pest control, pollinate $3 billion in crops and clean up grazing lands, which saves ranchers some $380 million a year. And these are "very conservative" estimates that probably represent only a fraction of the true value, reports Losey, associate professor of entomology at Cornell. This analysis of the economic value of these insect services is the first analysis of its type, said Losey, who co-authored the study with Mace Vaughan, Cornell M.S. '99, conservation director of the Xerces Society for Invertebrate Conservation in Portland, Ore., which works to protect native insect habitats through education and research......... Posted by: Kelly Permalink Source Ocean 'dead zones' posing extinction threat
Dead zones are occurring in many areas along the coasts of major continents, and they are spreading over larger areas of the sea floor. Because very few organisms can tolerate the lack of oxygen in these areas, they can destroy the habitat in which numerous organisms make their home.
The finding, by Rudolf Wu, Ph.D., and colleagues at the City University of Hong Kong, raises new concerns about vast areas of the world's oceans, known as "dead zones," that lack sufficient oxygen to sustain most sea life. Fish and other creatures trapped in these zones often die. Those that escape may be more vulnerable to predators and other stresses. This new study, Wu says, suggests these zones potentially pose a third threat to these species - an inability of their offspring to find mates and reproduce. The researchers found that low levels of dissolved oxygen, also known as hypoxia, can induce sex changes in embryonic fish, leading to an overabundance of males. As these predominately male fish mature, it is unlikely they will be able to reproduce in sufficient numbers to maintain sustainable populations, Wu says. Low oxygen levels also might reduce the quantity and quality of the eggs produced by female fish, diminishing their fertility, he adds......... Posted by: Kelly Permalink Source Story Of Earth's Earliest Animals From Embryos
Purported animal embryo fossils have been reported continuously over the last 12 years, mainly by paleontologists working in China. Researchers disagree about whether the fossils are actually animal embryos or even if they are animals. "The fossils look great. The problem is, if you know anything about embryos, their fossilization just doesn't seem likely," said IU Bloomington Professor of Biology Rudolf Raff, one of the report's authors. "It's like trying to fossilize soap bubbles. Some researchers showed that these fossils are being preserved with calcium phosphate, but they haven't explained how embryos could survive long enough for that to happen. We do that." The group of scientists, led by Rudolf Raff and IUB Department of Biology Chair Elizabeth Raff, explain what conditions are most likely to facilitate the fossilization of early animal embryos, as well as what factors are not likely to affect fossilization. They used two sea urchin species as models, Heliocidaris erythrogramma and Lytechinus pictus......... Posted by: Kelly Permalink Source |
|
Older Blog Entries 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23