November 5, 2007, 8:14 PM CT

Kids have a compass, but adults have the map

Even bird brains can get to know an entire continent -- but it takes them a year of migration to do so, suggests a Princeton research team.

The researchers have shown that migrating adult sparrows can find their way to their winter nesting grounds even after being thrown off course by thousands of miles, adjusting their flight plan to compensate for the displacement. However, similarly displaced juvenile birds, which have still not made the complete round trip, are only able to orient themselves southward, indicating that songbirds' innate sense of direction must be augmented with experience if they are to find their way home.

"This is the first experiment to show that when it comes to songbird migration, age makes a difference," said team member Martin Wikelski, an associate professor of ecology and evolutionary biology. "The results indicate that the adult birds possess a navigational map that encompasses at least the continental U.S., and possibly the entire globe."

Two longstanding questions about migrant songbirds are how quickly they recover when thrown off course -- as they can be when they encounter powerful winds -- and just what navigational tools they use to do so. To address the two questions, the team decided to fit a group of white-crowned sparrows with tiny radio transmitters no heavier than a paper clip and track their movements from a small plane......... Posted by: Kelly      Read more         Source

November 4, 2007, 8:11 PM CT

Divers find new species in Aleutians

There are unknown creatures lurking under the windswept islands of the Aleutians, as per a team of scientific divers from the University of Alaska Fairbanks.

This summer, while completing the second phase of a two-year broad scientific survey of the waters around the Aleutian Islands, researchers have discovered what may be three new marine organisms. This year's dives surveyed the western region of the Aleutians, from Attu to Amlia Island, while last year's assessment covered the eastern region.

During the dives, two potentially new species of sea anemones have been discovered. Stephen Jewett, a professor of marine biology and the dive leader on the expedition, says that these are "walking" or "swimming" anemones because they move across the seafloor as they feed. While most sea anemones are anchored to the seabed, a "swimming" anemone can detach and drift with ocean currents. The size of these anemones ranges from the size of a softball to the size of a basketball.

Another new species is a kelp or brown algae that researchers have named the "Golden V Kelp" or Aureophycus aleuticus. As per Mandy Lindeberg, an algae expert with NOAA's National Marine Fisheries Service and a member of the expedition, the kelp may represent a new genus, or even family, of the seaweed. Up to ten feet long, the kelp was discovered near thermal vents in the region of the Islands of the Four Mountains......... Posted by: Kelly      Read more         Source

Fri, 02 Nov 2007 01:09:59 GMT

Defensive Frog

It''s a frog. A very small frog.
But you better not mess around with it.

(via Arbroath) Posted by: Gerard      Read more     Source

October 31, 2007, 9:10 PM CT

Why do so many species live in tropical forests and coral reefs?

The latest development in a major debate over a controversial hypothesis of biodiversity and species abundance is the subject of a paper would be reported in the 1 November 2007 issue of the journal Nature. The authors report good agreement between the species richness of two of the world's most vulnerable ecosystems -- tropical forests and coral reefs -- and a simple mathematical model building on the so-called "neutral theory of biodiversity." "We're helping to refine and improve this theory because it might have important implications for the effort to protect terrestrial biodiversity from climate change and urban development," says Jayanth Banavar of the Department of Physics at Penn State, a member of the research team.

The Nature paper is based on a counterintuitive assumption of neutral theory: that one can largely ignore interactions between species in modeling patterns of species abundance. The authors are physicists Igor Volkov and Jayanth Banavar of Penn State University, plant biologist Stephen Hubbell of UCLA (formerly of the University of Georgia), and physicist Amos Maritan of the University of Padua in Italy.

Among ecological theorists, neutral theory has sparked a six-year quarrel over the fundamental assumptions of their discipline. The Nature paper counters another scientific team's claim in 2006 that coral-reef diversity "refutes" the neutral theory. At the same time, the paper by Volkov et al., would be published on 1 November 2007, modifies the classical version of neutral theory that appeared in a 2001 book by Hubbell. (Graham Bell of McGill University also developed a neutral theory independently of Hubbell.) Banavar, Maritan, Volkov, and their collaborators have been active in the development of a mathematical framework for understanding ecosystems that builds on and clarifies Hubbell's neutral theory......... Posted by: Kelly      Read more         Source

October 31, 2007, 9:05 PM CT

Tangled web of the insect, plant and parasite arms race

New insights into the evolutionary relationship between plant-dwelling insects and their parasites are revealed in the online open access journal BMC Biology. Scientists shed light on how sawflies evolved to escape their parasites and gain themselves an 'enemy-free space' for millions of years.

Tommi Nyman of the University of Joensuu in Finland together with colleagues from Sweden and Gera number of uncovered a food web involving willow trees, sawflies, and the parasites feeding on sawfly larvae. Sawflies (a group of insects correlation to bees and wasps) lay their larvae in willows creating galls, which are protruding growths of plant tissue. Nyman's group used data from galls collected from willows over an 18-year period. They classified 43 sawfly species using genetic analysis and assessed the degree of parasitism to which these insects had been subjected by 72 different parasites.

Their statistical analysis showed that parasitism promotes the insects' ecological divergence in a co-evolutionary arms race. The sawflies develop new gall-types and, in doing so, can escape the attentions of the parasites without having to switch host plant. Some parasites, however, have in turn adapted to the divergence in gall-types, driving further speciation. These processes partly explain the unusual diversity of herbivorous insects and their parasitoids......... Posted by: Kelly      Read more         Source

October 30, 2007, 10:20 PM CT

Gene that gives dogs black fur

A discovery about the genetics of coat color in dogs could help explain why humans come in different weights and vary in our abilities to cope with stress, a team led by scientists from the Stanford University School of Medicine reports.

The study, reported in the Nov. 2 issue of Science, answers a longtime mystery: What determines coat color in dogs" While scientists have known since the 1900s that most mammals share the same genetic mechanism to determine coat color, by the 1950s they began to suspect that dogs were different.

Now after swabbing the inner cheeks of hundreds of dogs and analyzing the DNA in the resulting samples, a team led by genetics professor Greg Barsh, MD, PhD, has nailed the gene. To the researchers' surprise, the gene makes a protein that's part of a large and variable family called defensins, thought to fight infections.

What is clear now is that this protein engages the melanocortin pathway, a circuit of molecular interactions that controls the type of melanin and amount of cortisol produced by the body. Barsh's lab has studied this pathway, which determines skin and hair color as well as stress adaptation and weight regulation, for 15 years.

The discovery of a new participant in this pathway opens up new vistas for drug research, said the article's co-first author, Sophie Candille, PhD, a former graduate student in Barsh's lab. Candille visited five Bay Area dog shows over six months to gather hundreds of samples by gently swabbing the inside of the dogs' cheeks with a brush......... Posted by: Kelly      Read more         Source

October 30, 2007, 10:16 PM CT

Underestimation of frog numbers causes concern

Frogs are vanishing from all the world's ecosystems with unprecedented speed. It is thought that more than 100 species have died out since 1980 alone.

In a paper reported in the online, open-access journal PLoS ONE, a team of experts, including scientists from the University of Canterbury, says the number of species has been strongly underestimated and they are calling for action.

The scientists from France and New Zealand collected and collated more than 500 DNA sequences, including 60 previously recognised species, occurring in the Guiana Shield, which harbours the largest continuous tract of virgin tropical rainforest.

This region of Amazonia comprises French Guiana, Suriname, Guyana, eastern Venezuela and northern Brazil.

PhD researcher Antoine Fouquet says the samples revealed an astonishing level of cryptic diversity, with the number of species identified potentially two hundred percent greater than previously thought.

Antoine says such underestimation of amphibian diversity has broad implications for the management of biodiversity, and especially that of a number of Neotropical amphibians which are considered highly threatened.

He says frogs are the "canaries in the coal mine" and their current decline is regarded as an indicator of the environmental crisis......... Posted by: Kelly      Read more         Source

October 30, 2007, 10:02 PM CT

Lithium dramatically increases lifespan in worms

ematode worms treated with lithium show a 46 percent increase in lifespan, raising the tantalizing question of whether humans taking the mood affecting drug are also taking an anti-aging medication. Results of the Buck Institute study, led by faculty member Gordon J. Lithgow, PhD, are currently published online in the Journal of Biological Chemistry.

Lithium has been used to treat mood affective disorders, including bipolar disease for decades. While the drug has been shown to protect neurons, the underlying mechanism of its therapeutic action is not understood. In humans, lithiums therapeutic range is very limited and the drug has serious side effects. The research provides a novel genetic approach to understanding how lithium works and highlights the utility of using the nematode C. elegans as a research subject in the field of pharmacogenetics. Pharmocogenetics involves the study of genetic factors that influence an organisms reaction to a drug.

In the study, researchers discovered that longevity was increased in the worms when the lithium turned down the activity of a gene that modulates the basic structure of chromosomes.

Lithgow believes that lithium impacts a number of genes. Understanding the genetic impact of lithium may allow us to engineer a treatment that has the same lifespan extending benefits, said Lithgow. One of the larger questions is whether the lifespan extending benefits of the drug are directly correlation to the fact that lithium protects neurons. The process of normal aging in humans is intrinsically associated with the onset of neurodegenerative disease. However, the cellular changes and events due to aging that impact neurodegeneration are still not understood said Lithgow. Studies involving compounds such as lithium could provide breakthroughs in the attempt to understand the biomedical link between aging and disease. Lithgow and his lab are now surveying tens of thousands of compounds for affects on aging......... Posted by: Kelly      Read more         Source

October 30, 2007, 10:01 PM CT

Role of growth factor in vertebrae formation

he Stowers Institutes Pourqui Lab has demonstrated the role of fibroblast growth factor (FGF) in the embryonic process of somitogenesis, an event mandatory for vertebrae formation, in a paper posted to the Web site of the journal Development. The paper will appear in the November print issue of the journal.

The Pourqui Lab has long studied the formation of vertebrae, and the lab team has made significant contributions to the currently accepted clock and wavefront explanation of somitogenesis. The theory suggests that a periodic mechanism the segmentation clock oscillator interacts with a molecular wavefront of differentiation, converts information from the clock into positional information, and allows for the formation of vertebrae precursors known as somites.

In this paper, the team successfully characterized and verified the proposed role of FGF signaling during somitogenesis using a mouse lacking the FGF receptor Fgfr1. They also published two important secondary findings correlation to FGF signaling: 1) FGF controls the clock, since the cyclic genes of all pathways (WNT, NOTCH, and FGF) eventually lose their dynamic expression; and 2) by pharmacological inhibition of FGF signaling, they identified a signaling hierarchy controlling clock oscillations downstream of FGF signaling......... Posted by: Kelly      Read more         Source

October 29, 2007, 7:47 PM CT

Dead clams tell many tales

Inventories of living and dead organisms could serve as a relatively fast, simple and inexpensive preliminary means of assessing human impact on ecosystems. The University of Chicago's Susan Kidwell explains how measuring the degree of live-dead mismatch could be used as an ecological tool in the Oct. 26 early online edition of the Proceedings of the National Academy of Sciences.

"We affect ecosystems in a number of different ways, but the effects of our actions are hard to pin down because we rarely have scientific data from before the onset of those impacts," said Kidwell, the William Rainey Harper Professor in Geophysical Sciences at Chicago.

Detailed ecological data, when they exist at all, often go back no more than 50 years. But researchers would prefer a deeper historical perspective that covers centuries or even a millennium. Live-dead studies can provide some of the needed perspective, as per Kidwell. In these studies, researchers collect data on the living organisms and the skeletal remains found in a specific ecosystem, then evaluate how closely they match.

"Death assemblages are what we call time-averaged. They're like time exposures," Kidwell said, "because skeletal remains can hang around for a long time. In fact, through radiocarbon and other dating methods we know that shells can persist within the upper few inches of the sea floor for decades and even millennia in some circumstances"......... Posted by: Kelly      Read more         Source