May 22, 2008, 10:29 PM CT

Over 50 percent of oceanic shark species threatened with extinction

22nd May 2008 The first study to determine the global threat status of 21 species of wide-ranging oceanic pelagic sharks and rays reveals serious overfishing and recommends key steps that governments can take to safeguard populations. These findings and recommendations for action are reported in the latest edition of Aquatic Conservation: Marine and Freshwater Ecosystems.

This international study, organised by the IUCN Shark Specialist Group (SSG), was conducted by 15 researchers from 13 different research institutes around the world, with additional contributions from scores of other SSG members.

The experts determined that 16 out of the 21 oceanic shark and ray species that are caught in high seas fisheries are at heightened risk of extinction due primarily to targeted fishing for valuable fins and meat as well as indirect take in other fisheries. In most cases, these catches are unregulated and unsustainable. The increasing demand for the delicacy shark fin soup, driven by rapidly growing Asian economies, means that often the valuable shark fins are retained and the carcasses discarded. Frequently, discarded sharks and rays are not even recorded.

Sharks and rays are especially vulnerable to overfishing due to their tendency to take a number of years to become sexually mature and have relatively few offspring......... Posted by: Kelly      Read more         Source

May 22, 2008, 10:20 PM CT

New family of gecko discovered

Scientists at the University of Minnesotas Bell Museum of Natural History and Pennsylvanias Villanova University have discovered a new family of gecko, the charismatic large-eyed lizard popularized by car insurance commercials.

Researchers have long been interested in geckos and their evolution because they are key biodiversity indicators and are found on nearly every continent. Scientists are also interested in the gecko because of the animals sticky toe pads, which allow them to scale rough and smooth surfaces -- a characteristic that may have human application in medicine, emergency rescue service and military industries.

Graduate students Tony Gamble from the University of Minnesota and Aaron Bauer from Villanova sequenced DNA from 44 species of gecko and used this genetic data to reconstruct the animals family tree. The resulting new classification is different from prior classifications, which are based solely on foot structure.

A classification based solely on foot structure will track selective pressure on the feet and not represent actual evolutionary history, said Gamble, who believes his discovery will add to a more accurate gecko family tree that, in turn, will allow researchers to better understand how sticky toe pads have evolved.

The scientists have named the new family Phyllodactylidae, referring to the leaf-shaped toes of a number of of the species in this group (phyllo meaning leaf: dactyl meaning toe). The new family consists of 103 species found in semiarid and tropical regions of North Africa, the Middle East, North and South America and the Caribbean......... Posted by: Kelly      Read more         Source

May 21, 2008, 8:54 PM CT

Relocation of endangered Chinese turtle

There are only four specimens of the Yangtze giant softshell turtle left on Earthone in the wild and three in captivity. In order to save this species from extinction, conservation partners from the Wildlife Conservation Society (WCS) and the Turtle Survival Alliance (TSA), working in conjunction with partners from two Chinese zoos and the China Zoo Society, recently paired two of them. A still reproductive, more than 80-year-old, female, living in Chinas Changsha Zoo has been introduced to the only known male in China, a more than 100-year-old living more than 600 miles away at the Suzhou Zoo.

The Bronx Zoo-based WCS and the Fort Worth Zoo-based TSA coordinated the critically important move; TSA provided much of the funding, animal reproduction and technical expertise while WCS provided veterinary and logistical support and coordination with wildlife partners in China and New York. Other project partners include Ocean Park and Kadoorie Farm and Botanic Garden, both in Hong Kong.

On Monday, May 5, turtle biologists, veterinarians, and zoo staff from partner organizations convened at the Changsha Zoo to collect and transport the female to the Suzhou Zoo where she joined her new mate to potentially save their entire species. The move was coordinated to coincide with the females reproductive cycle......... Posted by: Kelly      Read more         Source

May 21, 2008, 8:39 PM CT

North Pacific humpback whale populations rebounding

The number of humpback whales in the North Pacific Ocean has increased since international and federal protections were enacted in the 1960s and 70s, as per a new study funded primarily by NOAA and conducted by more than 400 whale scientists throughout the Pacific region.

However, some isolated populations of humpbacks, particularly those in the Western Pacific Ocean, have not recovered at the same rate and still suffer low numbers.

The new research reveals that the overall population of humpbacks has rebounded to approximately 18,000 to 20,000 animals. The population of humpback whales in the North Pacific, at least half of whom migrate between Alaska and Hawaii, numbered less than 1,500 in 1966 when international whaling for this species was banned. In the 1970s, federal laws including the Marine Mammal Protection Act and the Endangered Species Act provided additional protection.

NOAA is proud to have played a key role in initiating and funding this study, said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. It is only through this type of international cooperation that we can gauge our success and measure what additional work needs to be accomplished to protect highly migratory marine mammals......... Posted by: Kelly      Read more         Source

May 18, 2008, 10:25 PM CT

Wanted: a reason to divorce

Divorce is widespread, not only in humans, but also in socially monogamous birds like the blue tit. Behavioural ecologists Mihai Valcu and Bart Kempenaers from the Max Planck Institute for Ornithology in Seewiesen found divorce rates of up to 50% in a long-term study of this species. But why do partners split up? To answer this question, it helps to know who suffers and who benefits from the separation (Animal Behaviour, April 23, 2008).

Prior studies on small passerine birds, such as blue tits, have shown that females do better after divorce. This is because they had more offspring with a new partner. "These findings have led to the suggestion that the females should take the initiative to leave their partner", says Bart Kempenaers, Director of the Department Behavioural Ecology and Evolutionary Genetics at the Max Planck Institute for Ornithology in Seewiesen.

In their study however, Kempenaers and his colleague Mihai Valcu obtained evidence that the increased reproductive success of divorced females may not be caused by getting a better partner, but by leaving the prior home and moving to a better place. Such breeding dispersal is common in females, in contrast to males, who rarely leave their territory after a divorce.

To separate the effects of territory change and partner change, the Max Planck scientists investigated what happens to the divorced females that stay in or close to their former breeding area. They observed that in this case males, but not females, increased their fitness: they mated with larger females and had a higher breeding success in comparison to their former partner......... Posted by: Kelly      Read more         Source

May 15, 2008, 7:29 PM CT

Gravity-defying bird beak mystery

As Charles Darwin showed nearly 150 years ago, bird beaks are exquisitely adapted to the birds' feeding strategy. A team of MIT mathematicians and engineers has now explained exactly how some shorebirds use their long, thin beaks to defy gravity and transport food into their mouths.

The phalarope, usually found in western North America, takes advantage of surface interactions between its beak and water droplets to propel bits of food from the tip of its long beak to its mouth, the research team reports in the May 16 issue of Science.

These surface interactions depend on the chemical properties of the liquid involved, so phalaropes and about 20 other birds species that use this mechanism are extremely sensitive to anything that contaminates the water surface, particularly detergents or oil.

"Some species rely exclusively on this feeding mechanism, and so are extremely vulnerable to oil spills," said John Bush, MIT associate professor of applied mathematics and senior author of the paper.

Wildlife biologists have long noted the unusual feeding behavior of phalaropes, which spin in circles on the water, creating a vortex that sweeps small crustaceans up to the surface, just like tea leaves in a swirling tea cup.

The birds peck at the surface, picking up millimetric droplets of water with their prey trapped inside. Since the birds point their beaks downward during the feeding process, gravity must be overcome to get those droplets from the tip of the bird's long beak to its mouth. Until now, researchers have been puzzled as to how that happens......... Posted by: Kelly      Read more         Source

May 14, 2008, 8:54 PM CT

Monarch butterflies help explain why parasites harm hosts

It's a paradox that has confounded evolutionary biologists since Charles Darwin published On the Origin of Species in 1859: Since parasites depend on their hosts for survival, why do they harm them?

A new University of Georgia and Emory University study of monarch butterflies and the microscopic parasites that hitch a ride on them finds that the parasites strike a middle ground between the benefits gained by reproducing rapidly and the costs to their hosts. The study, reported in the early online edition of the journal Proceedings of the National Academy of Sciences, provides the first empirical evidence in a natural system of what's called the "trade-off hypothesis".

"Parasites have to harm their host to replicate and be transmitted," said lead author Jacobus de Roode, a former post-doctoral researcher at UGA and now an assistant professor at Emory University. "But what this study found is that if they harm their host too much, they'll suffer too. Conversely, this study also shows that it does not benefit the parasite to be maximally benign, because those parasites don't replicate enough to be effectively transmitted".

In a painstaking, three-year study conducted in the laboratory of Sonia Altizer, assistant professor in the UGA Odum School of Ecology, scientists infected monarch caterpillars with varying levels of spores from a protozoan parasite usually found in wild populations. After the adult butterflies emerged, females were mated and placed in outdoor mesh cages. The butterflies spread the parasites when they deposit spores onto eggs or leaves of the milkweed plants that caterpillars feed on. These spores are then consumed by caterpillars as they feed. Each butterfly had one stalk of milkweed in its cage, and every day for up to 30 days the scientists gave the butterflies a new stalk while taking the prior stalk back to the lab for analysis. The spores on the eggs and on the milkweed were counted, which is no easy task considering that each spore is 1/100th the size of the powdery scales on butterfly wings. A single egg can have more than 1,000 spores on it......... Posted by: Kelly      Read more         Source

May 14, 2008, 8:43 PM CT

Likely causative gene for Alzheimer's

The genetic profile of two large Georgia families with high rates of late-onset Alzheimer's disease points to a gene that may cause the disease, scientists say.

Genetic variations called single nucleotide polymorphisms, or SNPs, are common in DNA, but this pattern of SNPs shows up in nine out of 10 affected family members, says Dr. Shirley E. Poduslo, neuroscientist in the Medical College of Georgia Schools of Medicine and Graduate Studies and the Charlie Norwood Veterans Affairs Medical Center in Augusta.

The 10th family member had half the distinctive pattern. The SNPs also were found in the DNA of 36 percent of 200 other late-onset patients stored in the Alzheimers' DNA Bank.

"We were shocked; we had never seen anything like this before," Dr. Poduslo says of findings published online in the American Journal of Medical Genetics. "If we looked at unaffected spouses, their SNPs were all different. The variants consistently found in affected siblings are suggesting there is something in this gene. Now we have to go back and find what is in this gene that is making it so unique for Alzheimer's patients".

The variation was in the TRPC4AP gene, part of a large family of genes that is not well-studied but is believed to regulate calcium. Calcium is needed throughout the body but its dysregulation can result in inflammation, nerve cell death and possibly plaque formation as well, she says......... Posted by: Kelly      Read more         Source

May 14, 2008, 8:39 PM CT

Mouse can do without man's most treasured genes

The mouse is a stalwart stand-in for humans in medical research, thanks to genomes that are 85 percent identical. But identical genes may behave differently in mouse and man, a study by University of Michigan evolutionary biologists Ben-Yang Liao and Jianzhi Zhang reveals.

Their results, which have implications for the use of mouse models in studying human disease, appear in the current issue of the journal Proceedings of the National Academy of Sciences (PNAS).

"Everyone assumes that deletion of the same gene in the mouse and in humans produces the same phenotype (an observable trait such as presence or absence of a particular disease). That's the basis of using the mouse to study human disease," said Zhang, an associate professor of ecology and evolutionary biology. "Our results show that may not always be the case".

Zhang and his graduate student Liao focused their study on so-called essential genes-genes which, through their effects on survival or fertility, are necessary for organisms to reach sexual maturity and reproduce. They then homed in on 120 essential human genes for which the mouse has an identical counterpart that also has been studied. Next they consulted a database that catalogs the results of experiments in which the mouse equivalents of human genes are deleted, or "knocked out"......... Posted by: Kelly      Read more         Source

May 14, 2008, 7:39 PM CT

Restoring fish populations

You might think that stocking the Great Lakes with things like trout and salmon would be good for the herring gull. The birds often eat from the water, so it would be natural to assume that more fish would mean better dining. But a new report published in the April journal of Ecology by the Ecological Society of America says that the addition of species such as exotic salmon and trout to the area has not been good for the birds, demonstrating that fishery management actions can sometimes have very unexpected outcomes.

Craig Hebert (National Wildlife Research Center in Ottawa, Canada) and his team analyzed 25 years of data on the gulls and found that throughout the Great Lakes region, the birds were in poor health in many areas. Tests of their fatty acids showed an increase in the type of transfat that mostly comes from food produced by humans.

It seems that the birds are being forced to make a dietary shift from fish to terrestrial food, including garbage, says Hebert.

Although no one is certain why the birds are eating more garbage, evidence points to fish stocking. When exotic salmon and trout have been added to the waters, the birds seem to be out competed for their favorite prey of smaller fish, such as alewifes.

Herring gulls, which differ from the ring necked gulls that often populate American beaches and parking lots, are by no means endangered......... Posted by: Kelly      Read more         Source