November 6, 2008, 8:11 PM CT

Sea snakes seek out freshwater to slake thirst

Sea snakes may slither in saltwater, but they sip the sweet stuff.

So concludes a University of Florida zoologist in a paper appearing this month in the online edition of the November/recent issue of the journal Physiological and Biochemical Zoology.

Harvey Lillywhite says it has been the "long-standing dogma" that the roughly 60 species of venomous sea snakes worldwide satisfy their drinking needs by drinking seawater, with internal salt glands filtering and excreting the salt. Experiments with three species of captive sea kraits captured near Taiwan, however, observed that the snakes refused to drink saltwater even if thirsty - and then would drink only freshwater or heavily diluted saltwater.

"Our experiments demonstrate they actually dehydrate in sea water, and they'll only drink freshwater, or highly diluted brackish water with small concentrations of saltwater - 10 to 20 percent," Lilywhite said.

Harold Heatwole, a professor of zoology at North Carolina State University and expert on sea snakes, termed Lillywhite's conclusion "a very significant finding".

"This result probably holds the key to understanding the geographic distribution of sea snakes," Heatwole said.

The research may help explain why sea snakes tend to have patchy distributions and are most common in regions with abundant rainfall, Lillywhite said. Because global climate change tends to accentuate droughts in tropical regions, the findings also suggest that at least some species of sea snakes could be threatened now or in the future, he added......... Posted by: Kelly      Read more         Source

November 6, 2008, 7:50 PM CT

Turtles alter nesting dates due to temperature change

Turtles nesting along the Mississippi River and other areas are altering their nesting dates in response to rising temperatures, says a researcher from Iowa State University.

Fred Janzen, a professor in ecology, evolution and organismal biology, has studied turtle nesting habits and also accumulated research going back decades in order to track the habits of the turtles to find out when they make nests and lay eggs.

"The results have been astonishing," says Janzen. "In some cases such as regional populations of red-eared sliders, they are now nesting three weeks earlier than they did in the early part of 1990s. That is the fastest response to climate change of any species that I know of".

The turtles that changed their nesting habits were not only young turtles that are nesting for the first time, said Janzen, but were also older turtles that were changing their habits. This trait, called plasticity, helps animals alter their behavior in the short term until inherited behavior takes over.

"What we found was that in the late 1980s, painted turtles started nesting in early June, now it is on the order of 10 days or more earlier," said Janzen. "These behaviors are showing how the plasticity of the species is helping them survive, but we are wondering what the limit is to their ability to adapt"......... Posted by: Kelly      Read more         Source

October 31, 2008, 5:34 AM CT

Water fleas help ecologists understand population dynamics

(Santa Barbara, Calif.) A study of populations of tiny water fleas is helping ecologists to understand population dynamics, which may lead to predictions about the ecological consequences of environmental change.

The study is published in today's issue of the journal Nature The water flea, called Daphnia, plays a key role in the food web of a number of lakes.

Co-author Roger Nisbet, an ecologist based at the University of California, Santa Barbara, explained that a few animal populations, notably some insects, show huge "boom and bust" cycles. The populations alternate between periods of explosive growth when food is plentiful, followed by crashes when food is replaced too slowly to support the resulting large population.

This behavior is well understood by ecologists, and has been described by a number of simple mathematical models. However, most animal populations don't behave in this extreme way. "A key question is why," said Nisbet.

To answer the question, Nisbet and his two Canadian co-authors took a three-pronged approach that mandatory synthesizing evidence from field observations, experiments, and mathematical models. The theoretical foundation for this latest study was a mathematical theory developed several years ago by Nisbet and collaborators......... Posted by: Kelly      Read more         Source

October 28, 2008, 10:34 PM CT

Study rules out inbreeding as cause of amphibian deformities

Eventhough research has linked inbreeding with elevated rates of deformity in a wide variety of animals, a new study finds it plays no part in the high occurence rate of malformation among salamanders.

Purdue University scientists recently examined 2,000 adult and juvenile salamanders and observed that 8 percent had visible deformities, mainly consisting of missing, extra or dwarfed digits (equivalent to fingers and toes). That is double the rate of malformation found in newts, a related amphibian, but on par and with frequencies seen in a number of frog species, said assistant professor of forestry and natural resources Rod Williams.

"This is really the first study to test - and disprove - the hypothesis that inbreeding is responsible for malformations in salamanders," said Williams, corresponding author of the study published recently in the journal Biology Letters.

Like a number of types of amphibians, tiger salamanders return to the same pond throughout their lives to mate. Williams and his former doctoral adviser, lead author Andrew DeWoody, hypothesized that habitat fragmentation or other factors might increase the probability that related salamanders could return to the same spot and mate.

But their study found animals' genetic backgrounds to be uncorrelation to deformation rates; deformed salamanders were no more inbred than normal individuals. The population proved to be quite diverse, in fact, with roughly twice as much genetic variation as most land animals, DeWoody said......... Posted by: Kelly      Read more         Source

October 28, 2008, 10:32 PM CT

Amphibians'Ability to Predict Changes in Biodiversity

By Kim McDonald.

Biologists have long suspected that amphibians, whose moist permeable skins make them susceptible to slight changes in the environment, might be good bellwethers for impending alterations in biodiversity during rapid climate change.

Now two University of California biologists have verified the predictive power of this sensitive group of animals in a global study of species turnover among amphibians and birds. The study appears this week in the advance online version of the journal Proceedings of the National Academy of Sciences.

"Our study supports the role of amphibians as 'canaries in the coal mine'," said Lauren Buckley, a postdoctoral fellow at UC Santa Barbara's National Center for Ecological Analysis and Synthesis and the first author of the study. "Amphibians are likely to be the first to respond to environmental changes and their responses can forecast how other species will respond".

"Amphibians are much more tuned in to the changes in their specific environments," said Walter Jetz, an associate professor of biology at UC San Diego and the other author of the study. "They are much more sensitive to differences in environmental conditions as you move geographically from one location to another".

The two researchers used maps of the environment and amphibian and bird distributions to answer the question of how the environment-as well as the distribution of birds and amphibians-changes as one moves from one place to another around the globe......... Posted by: Kelly      Read more         Source

October 28, 2008, 9:56 PM CT

Global warming is killing frogs and salamanders

Frogs and salamanders, those amphibious bellwethers of environmental danger, are being killed in Yellowstone National Park. The predator, Stanford scientists say, is global warming.

Biology graduate student Sarah McMenamin spent three summers in a remote area of the park searching for frogs and salamanders in ponds that had been surveyed 15 years ago. Almost everywhere she looked, she found a catastrophic decrease in the population.

The amphibians need the ponds for their young to hatch, but high temperatures and drought are drying up the water. The frogs and salamanders lay eggs that have a gelatinous outer layerbasically "jelly eggs," McMenamin saysthat leaves them completely unsuitable for gestation on land. If the ponds dry up, so do the eggs. "If there isn't any water, then the animals simply don't breed," she said.

Biology Associate Professor Elizabeth Hadly, McMenamin's graduate adviser and co-author of a research paper published this week on the website of the Proceedings of the National Academy of Sciences, has worked in Yellowstone since 1981 and has witnessed the ponds going dry. "They're just blinking off," she said. "It's depressing".

"Precipitous declines of purportedly unthreatened amphibians in the world's oldest nature reserve indicate that the ecological effects of global warming are even more profound and are happening more rapidly than previously anticipated," the scientists wrote......... Posted by: Kelly      Read more         Source

October 22, 2008, 10:35 PM CT

Gene mutation in worms key to alcohol tolerance

The work follows a study carried out by Oregon Health and Science University, which suggested a link between a gene mutation in mice and tolerance to alcohol. Scientists at Liverpool have investigated this in worms, looking specifically at the role the gene plays in communication between cells in the nervous system.

This gene specifies the ways in which amino acids arrange themselves into a protein called UNC-18 or Munc18-1 in humans, an essential component of the nervous system. Scientists observed that a naturally occurring change in this gene can result in a change in the nature of one of the amino acids, which then alters communication between cells in the nervous system. As a result of these changes the nervous system becomes less sensitive to the effects of alcohol, allowing the body to consume more.

Professor Bob Burgoyne, Head of the University's School of Biomedical Sciences, explains: "Alcohol consumption can affect the nervous system in many ways. Low concentrations of alcohol can make the body more alert, but high concentrations can also reduce its activity, resulting in motor dysfunction and a lack of coordination. Some people, however, are more susceptible to these effects than others, but it has never been fully understood why this is.

"We used the nematode worm as a model to look at the role genes play in alcohol tolerance because all of the worm's genome has been characterised and we can therefore identify its genes easily. The gene we looked at corresponds to a gene in humans that performs the same function in the nervous system. Mutations in genes can occur naturally without any known cause and will persist if they are not especially harmful." ......... Posted by: Kelly      Read more         Source

October 16, 2008, 10:46 PM CT

Man's best friend recruited in the hunt for disease genes

For centuries man has had a uniquely close relationship with dogs as a working animal, for security and, perhaps most importantly, for companionship. Now, dogs are taking on a new role they are helping in the hunt for genetic mutations that lead to diseases in humans.

"Dogs get very similar diseases to humans," said Kerstin Lindblad-Toh of Uppsala University in Sweden and the Broad Institute of MIT and Harvard, Cambridge, Massachusetts. "If you ask a dog owner what sort of conditions their pets get, they will say cancer, allergies, eye diseases." .

Lindblad-Toh was speaking at the European Science Foundation's 3rd Functional Genomics Conference, held in Innsbruck, Austria, on 1-4 October. Functional genomics describes the way in which genes and their products, proteins, interact together in complex networks in living cells. If these interactions are abnormal, diseases can result. The Innsbruck meeting brought together more than 450 researchers from across Europe to discuss recent advances in the role of functional genomics in disease.

A number of canine diseases could share the same genetic basis in humans and dogs, Lindblad-Toh told the conference, and because dogs have been bred into clear isolated populations the different breeds it is often easier to detect a genetic flaw that leads to a disease than it is in humans. Once the rogue gene has been found in the dog, it could make it easier look for mutations in the same gene in man......... Posted by: Kelly      Read more         Source

October 16, 2008, 10:41 PM CT

Genes hold secret of survival of Antarctic 'antifreeze fish'

A genetic study of a fish that lives in the icy waters off Antarctica sheds light on the adaptations that enable it to survive in one of the harshest environments on the planet.

(To see an audio slide show on the fish, please go to: http://publicaffairs.illinois.edu/slideshows/Antarctic%5FNotothenioids/).

The study, in the Proceedings of the National Academy of Sciences, is the first to search the genome of an Antarctic notothenioid fish for clues to its astounding hardiness.

There are eight families of notothenioid fish, and five of them inhabit the Southern Ocean, the frigid sea that encircles the Antarctic continent. These fish can withstand temperatures that would turn most fish to ice. Their ability to live in the cold and.

oxygen-rich extremes is so extraordinary that they make up more than 90 percent of the fish biomass of the Southern Ocean.

University of Illinois animal biology professor Arthur DeVries discovered in the late 1960s that some notothenioids manufacture their own "antifreeze proteins." These proteins bind to ice crystals in the blood to prevent the fish from freezing.

In the new study, U. of I. animal biology professor C.-H. Christina Cheng and her colleagues at the Chinese Academy of Sciences sought comprehensive genetic clues that would help explain how the Antarctic notothenioids survive......... Posted by: Kelly      Read more         Source

October 15, 2008, 5:43 PM CT

Revealing the evolutionary history of threatened sea turtles

It's confirmed: Even though flatback turtles dine on fish, shrimp, and mollusks, they are closely correlation to primarily herbivorous green sea turtles. New genetic research carried out by Eugenia Naro-Maciel, a Marine Biodiversity Scientist at the Center for Biodiversity and Conservation at the American Museum of Natural History, and his colleagues clarifies our understanding of the evolutionary relationships among all seven sea turtle species.

Naro-Maciel and his colleagues used five nuclear DNA markers and two mitochondrial markers to test the evolutionary relationships of all species of marine turtlesleatherback, flatback, green, hawksbill, loggerhead, Kemp's Ridley, and Olive Ridleyand four 'outgroups,' or more distantly related animals. The results formed a well-supported phylogenetic tree, or cladogram, that tells the story of sea turtle evolution and is published in the journal Molecular Phylogenetics and Evolution

"The evolution of a specialized diet appears to have occurred three times, independently," says Naro-Maciel. "A number of sea turtles are carnivorous generalists. However, hawksbills tend to have a diet of glassthey eat toxic spongeswhile the leatherback consumes jellyfish and the green grazes mainly on algae or sea grass." Each of the species with specialized diets is positioned uniquely in the evolutionary tree......... Posted by: Kelly      Read more         Source