September 18, 2008, 9:01 PM CT

'Redesigned hammer' that forged evolution of pregnancy in mammals

New Haven, Conn. Yale scientists have shown that the origin and evolution of the placenta and uterus in mammals is linked to evolutionary changes in a single regulatory protein, as per a report in Proceedings of the National Academy of Sciences

"A number of past studies have shown that genes are regulated and altered by changes within their own structures. This is the first work suggesting that the evolution of transcription factors separate regulatory proteins may play an active role in the origin and evolution of structural innovations like the placenta and uterus," said senior author Gunter Wagner, the Alison Richard Professor of Ecology & Evolutionary Biology at Yale.

Pregnancy is a biologically unusual situation where one organism lives and develops inside another that is genetically different. Ordinarily, the immune system identifies and destroys the dissimilar tissue as if it were a parasite. But in some early mammals, changes 'turned down' the immune system, allowing the developing embryo to grow and thrive unchallenged by the maternal immune response.

With the evolution of the uterus and placenta, it became possible for mammals to protect their growing young and to ensure they were not exposed to an unpredictable environment, like their egg-laying relatives. This study identified one of the genetic switches that tempered the immune system and allowed formation of the placenta and internal development of young......... Posted by: Kelly      Read more         Source

September 10, 2008, 8:04 PM CT

Okapi survived poaching onslaught

A set of stripy legs in a camera trap photo snapped in an African forest indicates something to cheer about, say scientists from the Wildlife Conservation Society. The legs belong to an okapia rare forest giraffewhich apparently has survived in the Democratic Republic of Congo's Virunga National Park, despite over a decade of civil war and increased poaching.

"This is the first time this species has been captured on film in this park. Known to occur in the park from the early 1900s it had not been seen here for over 50 years. Two years ago sightings of dung and other tracks were made in the park by a team of pygmy trackers who knew Okapi sign. It is very encouraging to see that this animal has survived," said WCS researcher, Deo Kujirakwinja, who organized the recent camera trap survey. "A number of animals have suffered in this park as a result of the ten years of insecurity in the region, so it's encouraging to see that the okapi has survived".

Measuring up to 8 feet in length and standing up to 6 feet at the shoulder, the okapi has striped legs that give the animal a superficial resemblance to a zebra. It is, in fact, a close relative of the much larger giraffe. The animal's current range occurs in the Ituri Forest in northern DR Congo. They are classified as Near Threatened by the World Conservation Union (IUCN) and are at risk primarily from habitat destruction......... Posted by: Kelly      Read more         Source

September 10, 2008, 6:58 PM CT

Small males are more often meals

Female spiders are voracious predators and consume a wide range of prey, which sometimes includes their mates. Many hypotheses have been proposed for why females eat males before or after mating. Scientists Shawn Wilder and Ann Rypstra from Miami University in Ohio found, as per a research findings reported in the recent issue of the American Naturalist, that the answer may be simpler than previously thought. Males are more likely to be eaten if they are much smaller than females, which likely affects how easy they are to catch. In one species of spider, Hogna helluo, large males were never consumed while small males were consumed 80% of the time. This result was also confirmed when Wilder and Rypstra examined published data from a wide range of spider species. Males are more likely to be eaten in species where males are small relative to females.

Much research on sexual cannibalism has focused on a few extreme cases involving sexual selection and sperm competition. However, by looking at data on a wide range of spiders, Wilder and Rypstra discovered that the size of the male relative to the female (often referred to as sexual size dimorphism) determines how often sexual cannibalism occurs in a species. "We were surprised to find that such a simple characteristic such as how small males are relative to females has such a large effect on the frequency of sexual cannibalism," states Shawn Wilder. In a number of cases, sexual cannibalism may not be a complex balancing act of costs and benefits for males and females but rather a case of a hungry female eating a male when he is small enough to catch. In an interesting twist, evolution does not appear to be driving this relationship. For example, females would not become larger to consume more males because each male would then be a smaller meal to the larger female and males would not become smaller to be eaten more often because they would not get to mate as often. Rather, sexual cannibalism may be a byproduct of the evolution of large females and small males in a predatory species......... Posted by: Kelly      Read more         Source

August 31, 2008, 8:57 PM CT

Diversity among parasitic wasps

A tiny wasp that lays its eggs under the skin of unwitting caterpillars belongs to one of the most diverse groups of insects on Earth. Now researchers report that its diversity is even higher than previously thought.

(To see an audio slide show on the research, please go to: http://publicaffairs.illinois.edu/slideshows/Microgastrine.).

By combining ecological and genetic data with the painstaking detective work of taxonomy, the researchers have dramatically increased nearly doubling the estimated number of species reported of six very species-rich genera of parasitoid wasps.

The subfamily to which these wasps belong, Microgastrinae, gets its name from its tiny abdomen. The wasp itself is quite small, about the size of the lead at the tip of a pencil.

By looking at the physical characteristics (morphology) of more than 2,500 wasps, the taxonomists identified 171 provisional species of microgastrine braconid wasps. But a comparative sequence analysis of a piece of a specific gene, a technique called DNA barcoding, found that there were actually 313 provisional species.

(A provisional species is one that has not yet been given a formal scientific name, or in some cases, has not yet been found to be the same as a named species.)......... Posted by: Kelly      Read more         Source

August 27, 2008, 7:01 PM CT

Jamaican lizards' shows of strength mark territory at dawn, dusk

What does Jack LaLanne have in common with a Jamaican lizard?

Like the ageless fitness guru, the lizards greet each new day with vigorous push-ups. That's as per a new study showing that male Anolis lizards engage in impressive displays of reptilian strength -- push-ups, head bobs, and threatening extension of a colorful neck flap called a dewlap -- to defend their territory at dawn and dusk.

The lizards are the first animals known to mark dawn and dusk through visual displays, rather than the much better known chirping, tweeting, and other sounding off by birds, frogs, geckos, and primates.

Terry J. Ord, a postdoctoral researcher at Harvard University's Museum of Comparative Zoology and at the University of California, Davis, describes the Anolis lizards' unusual morning ritual in a forthcoming issue of the journal American Naturalist

"Anoles are highly visual species, so in that sense it's not surprising that they would use visual displays to mark territory," Ord says. "Still, the finding is surprising because these are the first animals known to use non-acoustic signaling at dawn and dusk".

Ord studied four species of Jamaican forest lizard: Anolis lineatopus, Anolis sagrei, Anolis grahami, and Anolis opalinus Female anoles establish small territories allowing access to food and other resources, while males stake out larger territories allowing them access to several females. The males spend much of the day sitting on tree trunks and displaying head motions, push-ups, and dewlap extensions, all to warn other males away from their territory......... Posted by: Kelly      Read more         Source

August 25, 2008, 10:23 PM CT

Animals adapt their vocal signals to social situations

A special recent issue of the Journal of Comparative Psychology, published by the American Psychological Association, presents a host of studies that investigate the way that animals adapt their calls, chirps, barks and whistles to their social situation.

The special issue, Acoustic Interaction in Animal Groups: Signaling in Noisy and Social Contexts, reports on findings from the natural world such as:

• Male gray treefrogs (Hyla versicolor) give out longer but fewer calls in reaction to the calls of other males. In other words, when these frogs are chorusing full blast, a male seeking female attention will change the rhythm of his call to break out of the chorus.
• Using an array of microphones to identify individual callers among wild bottlenose dolphins (Tursiops truncates), researchers observed that eventhough dolphins whistle more in social situations, individuals decrease their vocal output in large groups, when their whistles are more likely to be drowned out.
• Nestling tree swallows (Tachycineta bicolor) adjust their call output to parents when there's more noisy competition from the brood.
• Carolina chickadees (Poecile carolinensis) in larger social groups use calls with greater information than do individuals in smaller groups, and female-male interactions in opposite-sex chickadee pairs reflect the rate of male production of that distinctive chick-a-dee call.........
  
  
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August 21, 2008, 8:47 PM CT

Genetics reveals big fish that almost got away

Scientists from the University of Hawaii, the Wildlife Conservation Society, Smithsonian Tropical Research Institute, National Marine Fisheries Service and Projecto Meros do Brazil discovered a new species of fisha grouper that reaches more than six feet in length and can weigh nearly 1,000 pounds. This newly discovered species can be found roaming the tropical reefs of the Eastern Pacific Ocean.

Was the massive fish hiding among the corals and sea grass to evade marine biologists? No, it was just a case of mistaken identity, as explained in a recent genetic study in the journal Endangered Species Research

It turns out that goliath in the Atlanticwhich inhabit the tropical waters of the Americas and western Africaare not the same groupers that swim in Pacific waters, even though they look identical.

"For more than a century, ichthyologists have thought that Pacific and Atlantic goliath grouper were the same species, and the argument was settled before the widespread use of genetic techniques. The genetic data were the key to our finding: two species, one on each side of the isthmus.," said Dr. Matthew Craig of the Hawaii Institute of Marine Biology, lead author of the study.

Because the two populations of grouper are identical in body form and markings, they were both considered part of the same species: Epinephelus itajara. About three-and-a-half million years agobefore the Caribbean and the Pacific became separated by present-day Panamathey were the same species......... Posted by: Kelly      Read more         Source

August 21, 2008, 8:27 PM CT

Gas seismic work not affecting Gulf sperm whales

Noise can be irritating and possibly harmful for everything from mice to humans and maybe even 60-foot whales in the Gulf of Mexico.

In recent years, there has been concern that man-made noise may be a cause of stress for dolphins, whales and other marine mammals, but the results of a five-year study show that noise pollution particularly noise generated by seismic airguns during geophysical exploration for oil and gas seems to have minimal effect on endangered sperm whales in the Gulf of Mexico, say scientists from Texas A&M University who led the project and released their 323-page report today at the Houston Museum of Natural Science.

The multi-year $9 million study, the largest of its type ever undertaken and formally titled Sperm Whale Seismic Study in the Gulf of Mexico, was conducted by the Minerals Management Service and featured cooperation with the Office of Naval Research, the National Science Foundation and the National Fish and Wildlife Foundation. The project brought together scientists from eight universities, but it was managed overall by Texas A&M's Department of Oceanography, with research scientist Ann Jochens and professor Doug Biggs serving as principal investigators.

"The bottom line is that airgun noise from seismic surveys that are thousands of yards distant does not drive away sperm whales living in the Gulf," Biggs explains......... Posted by: Kelly      Read more         Source

August 18, 2008, 9:11 PM CT

Signals from the Atlantic Salmon Highway

For years researchers have struggled to understand the decline and slow recovery of Atlantic salmon, a once abundant and highly prized game and food fish native to New England rivers. Biologists agree that poor marine survival is affecting salmon in the U.S. and Canada, but specific causes are difficult to determine in the ocean. Small acoustic tags and associated technology may provide some answers.

Thirty of 150 Atlantic salmon smolts tagged by NOAA's Northeast Fisheries Science Center (NEFSC) in Maine's Penobscot River and released in Brewer, Maine in mid-May have crossed a line of underwater receivers off Halifax, Nova Scotia, the first fish to be tracked using the new global Ocean Tracking Network. The concept is similar to an EZ pass for highway toll booths, but for fish.

"The tracking system is deployed and working, which is great news," said John Kocik, who is leading the tagging project with colleague James Hawkes at the NEFSC's Maine Field Station in Orono, Maine. "We started ultrasonic tagging programs in Maine in 1997 and have learned much about salmon ecology in the estuaries and bays of the Gulf of Maine," Kocik said. "Our team is really excited that fish from our most recent work in the Penobscot River have been detected so far along on their migration northward. The first data provided valuable information about how long it took Atlantic salmon from the Penobscot River to reach Halifax."........ Posted by: Kelly      Read more         Source

August 18, 2008, 9:00 PM CT

Novel fungus helps beetles to digest hard wood

University Park, Pa. -- A little known fungus tucked away in the gut of Asian longhorned beetles helps the insect munch through the hardest of woods as per a team of entomologists and biochemists. Scientists say the discovery could lead to innovative methods of controlling the invasive pest, and potentially offer more efficient ways of breaking down plant biomass for generating biofuels.

Microbes in the gut of insects are known to break down cellulose, but little is known about how, or whether, insects degrade lignin. This natural polymer helps plants stay upright and protects them from most forms of microbial attack.

"Lignin is nature's plastic and any organism that wants to get to the sugars in a plant has to be able to get past this protective barrier," said Ming Tien, co-author of study and Penn State professor of biochemistry and molecular biology. "We suspect that the fungus produces enzymes that help the beetles degrade lignin".

Before this report, it was thought that insects are unable to extensively break down lignin, and that they get around the problem either by feasting on wood that has already degraded, or by living close to fungi that can degrade the wood for them.

But this theory fails to explain the ability of insects to feed and grow within healthy living trees......... Posted by: Kelly      Read more         Source