April 21, 2009, 5:20 AM CT

Lizards bask for more than warmth

Keeping warm isn't the only reason lizards and other cold-blooded critters bask in the sun. As per a research studyreported in the May/recent issue of Physiological and Biochemical Zoology, chameleons alter their sunbathing behavior based on their need for vitamin D.

"It's a longstanding assumption that thermoregulation is the only reason that lizards bask," says Kristopher Karsten, a biologist at Texas Christian University who led the study. "Our results suggest that in addition to thermoregulation, vitamin D regulation appears to have a significant impact on basking behavior as well".

Chameleons, like humans and most other vertebrates, get vitamin D in two ways: They can absorb it from food, and they can produce it in their skin. In order to produce vitamin D, however, the skin must be exposed to UV radiation.

To test whether chameleons alter their sunning behavior based on dietary vitamin D intake, Karsten observed the behavior of two different groups of chameleons. One group had high internal vitamin D levels, thanks to a diet of crickets dusted with a vitamin D powder. The other group ate regular crickets and had low vitamin D. The chameleons were then placed in individual outdoor enclosures that offered open area for direct sun, and a tree to offer filtered sun and shade......... Posted by: Kelly      Read more         Source

April 17, 2009, 5:22 AM CT

Museum specimens aid conservation efforts

There is a new tool for those developing conservation strategies for threatened species and landscapes: museum specimens. Richard Pearson and Christopher Raxworthy of the American Museum of Natural History dusted off many collections from Madagascar and used the location information linked to each species to test different ideas regarding the evolution of locally distributed endemism (unique species confined to small regions). The research paper published this month in Evolution found support for alternative hypotheses, suggesting that multiple processes develop local endemism. This improved knowledge of the processes that lead to endemism can help to identify priorities in conservation planning.

"Museum records can be used for conservation purposes, particularly because they tie together generations of data," says Pearson, a Biodiversity Scientist at the Museum's Center for Biodiversity and Conservation. "Madagascar is a unique natural laboratory for this project because of the large amount of local endemism and because the government's decision to set aside land has spurred an effort to prioritize the location of reserves within the landscape".

Madagascar is an island nation in the Indian Ocean that has been completely isolated from other land masses for the last 80 million years. Isolation has led to a high number of unique species like chameleons (Furcifer petteri), lemurs (Lemur catta), and day geckos (Phelsuma madagascariensis) which, in turn, has led Madagascar to be labeled a biodiversity "hotspot" by conservation groups. The Malagasy government pledged to set aside 10 percent of the land for conservation purposes as part of the 2003 World Parks Congress in Durban. Prior research papers have attempted to use species location records to determine which areas of the island would conserve the largest number of species......... Posted by: Kelly      Read more         Source

April 17, 2009, 5:20 AM CT

Size and suitability as a mate

A new study by scientists at the University of Alaska Fairbanks offers evidence that in one breed of northern seabird, the size of males' feather crests appears to be more than simple ornamentation.

Their study, published this month in of the Journal of Comparative Physiology B, shows that crest size appears to be a physical indicator of a male crested auklet's quality as a mate.

Researchers have long noted that female auklets prefer males with larger crests. But until recently, they did not know why. Low levels of stress hormones in males with larger crests indicate that they cope better with the stresses of reproduction, such as finding food, competing with thousands of other birds for mates and nest sites, and helping rear chicks.

"Females will divorce shorter-crested mates for the opportunity to mate with longer-crested males. Our study suggests that longer-crested males could contribute more to reproductive success because they have greater capacity to meet the social and physiological costs," said Hector Douglas, assistant professor of biology at the Kuskokwim Campus in Bethel.

Douglas and collaborator Alexander Kitaysky, an associate professor at the UAF Institute of Arctic Biology, say their results fit into a larger theory about animal societies......... Posted by: Kelly      Read more         Source

April 17, 2009, 5:17 AM CT

What life may have been like for dinosaurs?

During the last 540 million years, the earth's oxygen levels have fluctuated wildly. Knowing that the dinosaurs appeared around the time when oxygen levels were at their lowest at 12%, Tomasz Owerkowicz, Ruth Elsey and James Hicks wondered how these monsters coped at such low oxygen levels. But without a ready supply of dinosaurs to test their ideas on, Owerkowicz and Hicks turned to a modern relative: the alligator. 'We knew testing the effects of different oxygen levels would work with alligators,' Owerkowicz explains, 'because crocodilians have survived in their basic shape and form for 220 million years. They must be doing something right to have survived the oxygen fluctuations.' Choosing to start at the beginning of alligator development, the trio decided to try incubating alligator eggs at different oxygen levels, to find out how the youngsters grew and developed and publish their results on April 17 2009 in The Journal of Experimental Biology at http://jeb.biologists.org.

Receiving newly laid alligator eggs from Elsey at the Rockefeller Wildlife Refuge, Owerkowicz divided the eggs into groups incubated at 12% (low) oxygen, 21% (normal) oxygen and 30% (high) oxygen, and waited to see what would happen. After almost 10 weeks of waiting, the eggs began hatching and Owerkowicz could see that there were no obvious differences between the alligators that developed in normal and high oxygen atmospheres......... Posted by: Kelly      Read more         Source

April 16, 2009, 5:26 AM CT

Red pandas and sweet tooth

PHILADELPHIA (April 15, 2009) -- Scientists from the Monell Center report that the red panda is the first non-primate mammal to display a liking for the artificial sweetener aspartame. This unexpected affinity for an artificial sweetener may reflect structural variation in the red panda's sweet taste receptor.

The findings may shed light on how taste preferences and diet choice are shaped by molecular differences in taste receptors.

"The red panda's unique taste receptor gives us a tool to broaden our understanding of how we detect sweet taste," said the paper's senior author, Joseph G. Brand, PhD, a biophysicist at Monell. "Greater insight into why we like artificial sweeteners could eventually lead to the development of more acceptable sugar substitutes, potentially benefiting diabetics and other individuals on sugar-restricted diets".

A number of species like sweet-tasting foods, but there are some exceptions. In an earlier study, Brand and Monell comparative geneticist Xia Li, PhD, reported that cats both domestic and wild can not taste sweets due to a defect in one of the genes that codes for the sweet taste receptor.

The current research extended those findings by relating sweet preferences to genetic analyses of sweet receptor structure in six related species. Like the cat, each of the species tested -- red panda, ferret, genet, meerkat, mongoose, and lion -- belongs to the Order Carnivora......... Posted by: Kelly      Read more         Source

April 8, 2009, 5:24 AM CT

Studying migration of threatened whale sharks

Whale sharks -- giants of the fish world that strike terror only among tiny creatures like the plankton and krill they eat -- are imperiled by over-fishing of the species in parts of its ocean range.

That threat is underscored in a newly released study from geneticists led by Jennifer Schmidt, University of Illinois at Chicago associate professor of biological sciences, reported online April 7 in the journal PLoS One

Schmidt and her colleagues studied the DNA of 68 whale sharks from 11 locations across the Indian and Pacific Oceans and the Caribbean Sea -- an area that covers most of the shark's known range. Results showed little genetic variation between the populations, which indicates migration and interbreeding among far-flung populations of the big fish.

"Our data show that whale sharks found in different oceans are genetically quite similar, which means that animals move and interbreed between populations," said Schmidt. "From a conservation standpoint, it means that whale sharks in protected waters cannot be assumed to stay in those waters, but may move into areas where they appears to be in danger".

A tropical fish that can grow 50 feet or longer and weigh over 20 tons, a whale shark's range can span oceans. They do not breed until they are about 25 to 30 years old, so it will take a long time for the species to recover from recent population declines......... Posted by: Kelly      Read more         Source

April 8, 2009, 5:15 AM CT

Switch one dietary poison for another

As the U.S. Southwest grew warmer between 18,700 and 10,000 years ago, juniper trees vanished from what is now the Mojave Desert, robbing woodrats of their favorite food.

Now biologists have narrowed the hunt for detoxification genes that let the rodents eat the toxic creosote bushes that replaced junipers.

"It was either eat it or move out," says biologist Denise Dearing of the University of Utah, main author of a paper detailing the results, published on-line on April 7, 2009, in the journal Molecular Ecology

"This is an excellent example of research that bridges the fields of ecology and physiology," says Mary Chamberlin, acting deputy division director of the National Science Foundation (NSF)'s Division of Integrative Organismal Systems, which funded the research.

"It underscores the importance of studying organismal biology in order to understand how animals may or may not adapt to changes in their ecosystems".

During the study, eight woodrats were captured from each of two western regions: the Mojave Desert and the cooler Great Basin. Rats from both areas were fed rabbit chow mixed with either creosote or juniper.

The researchers then scanned the rodents' genetic blueprints to look for active genes known as "biotransformation genes" because they produce liver enzymes to detoxify the poisons in creosote and the less-toxic juniper......... Posted by: Kelly      Read more         Source

April 2, 2009, 5:21 AM CT

Sexy or Repulsive?

Butterflies seem able to both attract mates and ward off predators using different sides of their wings, as per new research by Yale University biologists.

Trying to find the balance between these two crucial behaviors is one of nature's oldest dilemmas, as per Jeffrey Oliver, a postdoctoral associate in Yale's Department of Ecology and Evolutionary Biology and main author on the study, which appears online today in the journal Proceedings of the Royal Society B: Biological Sciences.

"You want to be noticeable and desirable for mates, but other onlookers, including predators, are paying attention to those signals as well".

Oliver was interested in whether the eyespots on the upperside of butterflies' wings - specifically, those of bush brown butterflies - serve a different purpose than the ones on the underside. Ever since Darwin's time, biologists (including Darwin himself) have postulated whether the upperside patterns could be used to attract mates, while at the same time, those on the underside could help avoid predators.

Working with Yale biologist Antonia Monteiro, Oliver used new tools to put the old theory to the test. Using different evolutionary models, he observed that the eyespots on the upperside of the butterflies' wings appear to evolve much more quickly than those on the underside, meaning they appear and disappear frequently through the course of evolution. The result is consistent with the theory that these are used to attract mates, as signals used for sexual selection tend to evolve faster than others......... Posted by: Kelly      Read more         Source

March 31, 2009, 5:14 AM CT

Why a chimp is so strong?

February's brutal chimpanzee attack, during which a pet chimp inflicted devastating injuries on a Connecticut woman, was a stark reminder that chimps are much stronger than humansas much as four-times stronger, some scientists believe. But what is it that makes our closest primate cousins so much stronger than we are? One possible explanation is that great apes simply have more powerful muscles. Indeed, biologists have uncovered differences in muscle architecture between chimpanzees and humans. But evolutionary biologist Alan Walker, a professor at Penn State University, thinks muscles may only be part of the story.

In an article to be reported in the recent issue of Current Anthropology, Walker argues that humans may lack the strength of chimps because our nervous systems exert more control over our muscles. Our fine motor control prevents great feats of strength, but allows us to perform delicate and uniquely human tasks.

Walker's hypothesis stems partly from a finding by primatologist Ann MacLarnon. MacLarnon showed that, relative to body mass, chimps have much less grey matter in their spinal cords than humans have. Spinal grey matter contains large numbers of motor neuronsnerves cells that connect to muscle fibers and regulate muscle movement.

More grey matter in humans means more motor neurons, Walker proposes. And having more motor neurons means more muscle control......... Posted by: Kelly      Read more         Source

March 26, 2009, 9:44 PM CT

MRI for a Gorilla

Talk about house calls! The Wildlife Conservation Society thanks The Brain Tumor Foundation and its "Road To Early Detection" campaign for their assistance in performing a brain scan on a gorilla at the Bronx Zoo.

The on-site procedureperformed by dozens of wildlife veterinarians, zookeepers, and medical personnel from several institutionswas made possible by the Bobby Murcer Mobile MRI Unit, a 48-foot-long MRI facility on wheels that conducted a comprehensive neurological scan on the brain of Fubo, a 42-year-old western lowland gorilla. Fubo is one of two adult males, or silverbacks, living in the Bronx Zoo's Congo Gorilla Forest exhibit, which houses one of the largest breeding groups of western lowland gorillas in North America (more than 20 individuals). Fubo recently suffered a seizure, prompting WCS health and curatorial staff to seek out a neurological diagnosis.

The Brain Tumor Foundation responded to WCS's request for assistance with Fubo by sending its mobile MRI facility and staff to the Bronx Zoo's campus, free of charge. The gorilla was sedated for the two-hour procedure, placed into the MRI's magnetic tube for the scans (a snug fit for a patient with gorilla-sized shoulders), and returned to the Congo Gorilla Forest as planned. Under strict protocol, the MRI Unit was cleaned and sanitized after the procedure......... Posted by: Kelly      Read more         Source