In response to this crisis, researchers at UC Santa Barbara's National Center for Ecological Analysis and Synthesis (NCEAS) have conducted a pioneering study that illustrates how severely disease threatens the long-term survival of wild gorillas and chimpanzees. It also explores the status of potential interventions that may help ensure their continued existence.

The article, "Consequences of Non-Intervention for Infectious Disease in African Great Apes," was recently published in the online journal PLoS ONE. The study indicates that mortality rates comparable to those recently reported for disease outbreaks in wild populations are not sustainable.

Sadie Ryan, the lead author, is assistant professor of ecology at SUNY-ESF in Syracuse, N.Y.; and Walsh is a quantitative ecologist at the University of Cambridge, England.

Modeling demonstrated that recovery times to current population levels from a single disease outbreak, under very optimistic rates of recovery, would range from five years for a flu-like outbreak, to 131 years for an Ebola virus outbreak that killed 96 percent of the population, according to the study. Population resilience is central to assessing disease threat because gorillas and chimpanzees reproduce more slowly than virtually any other animal on earth, including humans.

"These disease mortality rates are particularly troubling, given the rising pathogen risk due to increasing human contact with wild apes, associated with their habituation for tourism, poaching, and the increase in population pressure around protected areas," said Ryan.

"These small populations of great apes are the last vestiges of our closest relatives, so there is a huge emotional response when it comes to the question of intervention. Should we or can we wait, or should we use proactive intervention by vaccinating ahead of time?"

Both "naturally" occurring pathogens, such as Ebola and Simian Immunodeficiency Virus (SIV), and respiratory pathogens transmitted from humans, such as the common cold and flu viruses, have been confirmed as important sources of mortality in wild gorillas and chimpanzees, and the rate of pathogen spillover from humans to African apes is known to be increasing.

Although awareness of the threat has spread throughout the scientific community, interventions such as vaccination and treatment remain very controversial, the researchers noted.

Because of the scarcity of diagnostic data on exactly which pathogens infect apes and at what rates, Ryan and Walsh found it difficult to rigorously quantify how increased tourism would translate into increased disease pressure on ape populations.

As a result, they assessed and compared potential future disease spillover risk - in terms of vaccination rates among humans that may come into contact with wild apes, and the availability of vaccines against potentially threatening diseases - with non-interventionist responses, such as limiting tourist access to the primates, community health programs, increased vigilance, and reactive veterinary intervention.

Based on their findings, Ryan and Walsh suggest that the great ape conservation community "pursue and promote treatment and vaccination as weapons in the arsenal for fighting the decline of African apes."

They recommend that field studies on safe and efficient methods for delivering treatments and vaccines orally be conducted, along with evaluating the cost-effectiveness of all ape conservation strategies.

"We looked at the rates of vaccination in human populations both in host countries and potential tourists, and at the potential vaccines in development that could be used for great apes," Ryan said.

"But we need to do more research when outbreaks occur by mobilizing the entire research community in order to better understand what is going on."

]]> Wed, 08 FEB 2012 08:56:32 AEST Stanford CA (SPX) Feb 08, 2012 - Plants leaves are sealed with a gas-tight wax layer to prevent water loss. Plants breathe through microscopic pores called stomata (Greek for mouths) on the surfaces of leaves. Over 40% of the carbon dioxide, CO2, in the atmosphere passes through stomata each year, as well a water volume twice that of the whole atmosphere.

As the key conduits for CO2 uptake and water evaporation, stomata are critical for both our climate and plant productivity. Thus, not surprisingly, the total number and distribution of stomata are strictly regulated by plants to optimize photosynthesis while minimizing water loss.

The mechanisms for such regulation have remained elusive. New research from Carnegie's Zhiyong Wang, Tae-Wuk Kim and Dominique Bergmann demonstrates that certain plant steroid hormones, called brassinosteroids, play a crucial role in this regulating the number of stomata in the leaf. Their work is published online February 5 by Nature.

Brassinosteroids are found throughout the plant kingdom and regulate many aspects of growth and development, including inhibition of photosynthetic genes when there is insufficient light for photosynthesis. Mutant plants that are deficient in brassinosteroids show defects at many phases of the plant life cycle including reduced seed germination, activation of light-induced genes and growth behavior in the dark, dwarfism, and sterility.

Wang, lead author Kim and their colleagues Marta Michniewicz and Bergmann set out to determine brassinosteroid's role in stomatal development.

They found that mutant plants that are brassinosteroid deficient, or lack sensitivity to brassinosteroids, were observed to have excessive and unevenly-distributed stomata, leading the team to ask what role this class of hormones plays in the developmental process for these crucial plant organs.

Wang and his colleagues had previously determined that when brassinosteroid binds to a receptor on the surface of a plant cell, it initiates a chain of signal transduction that results in certain genes being turned on or off within the cell's nucleus. But this research showed that one of the proteins involved in this chain, called BIN2, is also involved in a completely separate pathway that regulates the development of stomata.

The team found that BIN2--which is similar to a protein found in humans--had an inhibiting effect on a key protein in the stomatal-development regulatory system.

This second protein is called called YODA and it also has a similar counterpart in humans. In the absence of brassinosteroid, BIN2 inhibits YODA, which allows stomata formation. When brassinosteroid is present, it causes inactivation of BIN2, and this allows YODA to inhibit stomatal development.

"This research supports the role of brassinosteroid as a master regulator that coordinates both physiological and development aspects of plant growth," Wang said.

"Because brassinosteroid is one of the best-understood chemical pathways in plant physiology, these results could help scientists who are researching many other plant cell systems as well."

]]> Wed, 08 FEB 2012 08:56:32 AEST Bristol, UK (SPX) Feb 08, 2012 - Some 165 million years ago, the world was host to a diversity of sounds. Primitive bushcrickets and croaking amphibians were among the first animals to produce loud sounds by stridulation (rubbing certain body parts together). Modern-day bushcrickets - also known as katydids - produce mating calls by rubbing a row of teeth on one wing against a plectrum on the other wing but how their primitive ancestors produced sound and what their songs actually sounded like was unknown - until now.

On discovering several insect fossils, a group of Chinese palaeontologists, including Jun-Jie Gu and Professor Dong Ren from the Capital Normal University in Beijing, contacted Dr Fernando Montealegre-Zapata and Professor Daniel Robert, both experts in the biomechanics of singing and hearing in insects, in Bristol's School of Biological Sciences. The group also teamed up with Dr Michael Engel of the University of Kansas, USA, a leading expert on insect evolution.

The Chinese researchers provided an exceptionally detailed bushcricket fossil from the Mid Jurassic period. The specimen had such well-preserved wing features that the details of its stridulating organs were clearly visible under an optical microscope. Such information has never been obtained before from insect fossils. It was identified as a new fossil species and named Archaboilus musicus by the Beijing-Kansas team.

Dr Montealegre-Z and Professor Robert examined the anatomical construction of the fossil's song apparatus, and compared it to 59 living bushcricket species. They concluded that this animal must have produced musical songs, broadcasting pure, single frequencies.

Professor Robert said: "This discovery indicates that pure tone communication was already exploited by animals in the middle Jurassic, some 165 million years ago. For Archaboilus, as for living bushcricket species, singing constitutes a key component of mate attraction. Singing loud and clear advertises the presence, location and quality of the singer, a message that females choose to respond to - or not. Using a single tone, the male's call carries further and better, and therefore is likely to serenade more females. However, it also makes the male more conspicuous to predators if they have also evolved ears to eavesdrop on these mating calls."

The research, published in PNAS, implies that the acoustic environment was already quite busy 165 million years ago with many animals (such as amphibians and other arthropods) singing at the same time, possibly chorusing, within the additional background noise produced by waterfalls, streams and wind.

Amazingly, based on the detailed morphology of Archaboilus' wings, Dr Fernando Montealegre-Z could reconstruct the songs emitted by these ancient insects.

Following biomechanical principles that he discovered some years ago, Dr Montealegre-Z established that A. musicus sang a tone pitched at 6.4kHz and that every bout of singing lasted 16 milliseconds. This turned out to be enough information to acoustically reconstruct the song itself, possibly the most ancient known musical song documented to date. [To hear the song, download file here]

This paleobioacoustical analysis also provides a unique insight into the ecology of an extinct insect.

Dr Montealegre-Z said: "Using a low-pitched song, A. musicus was acoustically adapted to long-distance communication in a lightly cluttered environment, such as a Jurassic forest. Today, all species of katydids that use musical calls are nocturnal so musical calls in the Jurassic were also most likely an adaptation to nocturnal life. Being nocturnal, Archaboilus musicus probably escaped from diurnal predators like Archaeopterix, but it cannot be ruled out that Jurassic insectivorous mammals like Morganucodon and Dryolestes also listened to the calls of Archaboilus and preyed on them.

"This Jurassic bushcricket thus sheds light on the potential auditory capacity of other animals, and helps us learn a little more about the ambiance of a world long gone. It also suggests the evolutionary mechanisms that drove modern bushcrickets to develop ultrasonic signals for sexual pairing and for avoiding an increasingly relevant echolocating predator, but that only happened 100 million years later, possibly with the appearance of bats."

]]> Wed, 08 FEB 2012 08:56:32 AEST Jakarta (AFP) Feb 7, 2012 - Conservation group WWF said it spotted 18 critically endangered Irrawaddy dolphins in Indonesian waters off Borneo island Tuesday and called for greater protection of the species' habitat.

There is little data on the Irrawaddy dolphin -- which resembles the common bottlenose dolphin but has no beak and a snub dorsal fin -- and no comprehensive survey has been conducted to measure its global population.

"In the past, locals and fishermen reported seeing the dolphins, but we have never recorded them until now," WWF conservation biologist Albertus Tjiu told AFP.

Over five days a research team surveyed 260 kilometres (160 miles) along the coast of West Kalimantan, on Indonesia's half of Borneo island, and spotted the species travelling in small groups.

The sightings show that the dolphins' habitat is still intact, despite degradation by hundreds of pulp and charcoal plantations by the coast, Tjiu said.

The team also encountered three Indo-Pacific humpback dolphins that live in the same type of ecosystem.

The two dolphin species live in biodiverse mangroves -- estuaries of dense tropical trees or shrubs that grow along coastal sediment, resembling muddy swampland.

Mangroves have a distinct vegetation that, like peatland forests, can take thousands of years to fully form.

"We call on all businesses operating in the area to act sustainably to conserve the mangroves. We expect to discover more dolphins when we finish the study," Tjiu said.

Critically endangered Irrawaddy dolphins have been recorded in the Mekong River in Cambodia; the Ayeyawardi River in Myanmar and the Mahakam River of East Kalimantan.

Populations of Irrawaddy dolphin in other areas are categorised as vulnerable.

In 2009, biologists recorded the world's biggest Irrawaddy dolphin population of around 6,000 in Bangladesh. Prior to that it was believed only hundreds existed.

Irrawaddy dolphins, like many other marine species, often die entangled in fishing nets and in crab traps, as well as from electric fishing.

Mangroves, which also offer natural flood protection from rising sea levels, are under threat of unsustainable agriculture and climate change.

Indonesia is home to some of the most biodiverse forest and marine ecosystems. Rampant land conversion for paper and palm oil plantations, among others, has destroyed swathes of land, particularly in Kalimantan.

]]> Wed, 08 FEB 2012 08:56:32 AEST La Jolla CA (SPX) Feb 07, 2012 - One of the big mysteries in biology is why cells age. Now scientists at the Salk Institute for Biological Studies report that they have discovered a weakness in a component of brain cells that may explain how the aging process occurs in the brain.

The scientists discovered that certain proteins, called extremely long-lived proteins (ELLPs), which are found on the surface of the nucleus of neurons, have a remarkably long lifespan.

While the lifespan of most proteins totals two days or less, the Salk Institute researchers identified ELLPs in the rat brain that were as old as the organism, a finding they reported in Science.

The Salk scientists are the first to discover an essential intracellular machine whose components include proteins of this age. Their results suggest the proteins last an entire lifetime, without being replaced.

ELLPs make up the transport channels on the surface of the nucleus; gates that control what materials enter and exit. Their long lifespan might be an advantage if not for the wear-and-tear that these proteins experience over time. Unlike other proteins in the body, ELLPs are not replaced when they incur aberrant chemical modifications and other damage.

Damage to the ELLPs weakens the ability of the three-dimensional transport channels that are composed of these proteins to safeguard the cell's nucleus from toxins, says Martin Hetzer, a professor in Salk's Molecular and Cell Biology Laboratory, who headed the research. These toxins may alter the cell's DNA and thereby the activity of genes, resulting in cellular aging.

Funded by the Ellison Medical Foundation and the Glenn Foundation for Medical Research, Hetzer's research group is the only lab in the world that is investigating the role of these transport channels, called the nuclear pore complex (NPC), in the aging process.

Previous studies have revealed that alterations in gene expression underlie the aging process. But, until the Hetzer lab's discovery that mammals' NPCs possess an Achilles' heel that allows DNA-damaging toxins to enter the nucleus, the scientific community has had few solid clues about how these gene alterations occur.

"The fundamental defining feature of aging is an overall decline in the functional capacity of various organs such as the heart and the brain," says Hetzer.

"This decline results from deterioration of the homeostasis, or internal stability, within the constituent cells of those organs. Recent research in several laboratories has linked breakdown of protein homeostasis to declining cell function."

The results that Hetzer and his team report suggest that declining neuron function may originate in ELLPs that deteriorate as a result of damage over time.

"Most cells, but not neurons, combat functional deterioration of their protein components through the process of protein turnover, in which the potentially impaired parts of the proteins are replaced with new functional copies," says Hetzer.

"Our results also suggest that nuclear pore deterioration might be a general aging mechanism leading to age-related defects in nuclear function, such as the loss of youthful gene expression programs," he adds.

The findings may prove relevant to understanding the molecular origins of aging and such neurodegenerative disorders as Alzheimer's disease and Parkinson's disease.

In previous studies, Hetzer and his team discovered large filaments in the nuclei of neurons of old mice and rats, whose origins they traced to the cytoplasm. Such filaments have been linked to various neurological disorders including Parkinson's disease. Whether the misplaced molecules are a cause, or a result, of the disease has not yet been determined.

Also in previous studies, Hetzer and his team documented age-dependent declines in the functioning of NPCs in the neurons of healthy aging rats, which are laboratory models of human biology.

Hetzer's team includes his colleagues at the Salk Institute as well as John Yates III, a professor in the Department of Chemical Physiology of The Scripps Research Institute.

When Hetzer decided three years ago to investigate whether the NPC plays a role in initiating or contributing to the onset of aging and certain neurodegenerative diseases, some members of the scientific community warned him that such a study was too bold and would be difficult and expensive to conduct. But Hetzer was determined despite the warnings.

He adds that without foundation funding, the study would not have progressed to the point that its findings are published in a leading journal.

]]> Wed, 08 FEB 2012 08:56:32 AEST Durham NC (SPX) Feb 07, 2012 - Most creatures face compromises when they reproduce - the more energy they devote to having lots of babies, the less they can invest in each one. But do the same tradeoffs hold true for plants? Biologists have long assumed that plants with bigger, showier flowers can make fewer of them per plant. But the data don't always hold up, scientists say. A new study by researchers at the National Evolutionary Synthesis Center may help explain why.

"We expect size-number tradeoffs to be universal, but when we look at plants we don't always find them, and we wanted to know why that might be," said co-author Christina Caruso of the University of Guelph.

Because plants can't move, many rely on their showy, colorful blossoms to entice birds, bats and insects to deliver pollen from one flower to the next. Plants use a range of strategies to attract their suitors, from a single large flower per plant, to hundreds of tiny blooms.

But even if bigger, more plentiful blossoms are useful for attracting pollinators, no creature can do it all in the face of limited time, energy or resources. For most living things, the necessary tradeoff between quantity and quality means that those with numerous offspring can only invest so much energy in each one.

We see the same thing in people, said co-author Hafiz Maherali of the University of Guelph: "Human babies born as twins or triplets generally have lower birth weights than babies born singly," Maherali said.

From daffodils to dogwoods, models assume that flowering plants are no exception to the tradeoff rule. At least in theory, species with bigger blossoms should make fewer of them per plant. But in many plant studies the data don't always hold up.

"Perhaps tradeoffs aren't as pervasive as we think," Caruso said. "Or maybe plants experience the same [size-number] tradeoffs as other living things, but for various reasons they're harder to detect," she added.

Over the years, several hypotheses have been proposed. One possibility, researchers say, is that differences in resource acquisition ability and overall plant size make tradeoffs harder to detect. "Some plants are better at fixing carbon and getting water and nitrogen than others," Caruso explained. If larger plants are able to make bigger, more plentiful blooms than their smaller counterparts, an inverse connection between flower size and number could be trickier to spot.

To test the idea, the researchers planted more than 1000 monkeyflowers of the species Mimulus guttatus in a greenhouse at the University of Guelph in Ontario, Canada. Monkeyflowers are common wildflowers found in western North America, from the Sonoran desert to western Alaska.

Some Mimulus guttatus plants produce many flowers, and others produce few. To boost the variation in overall plant size, half the plants in the greenhouse experiment got fertilizer, and the other half went without.

The researchers measured the correlation between flower size and flower number, and at the end of the season they harvested and weighed each plant.

They found that larger plants made bigger, more plentiful blooms, just as they suspected. But when they accounted for differences in overall plant size, the underlying tradeoff between flower size and flower number still held true.

In a second experiment they compiled data for 83 plant genera found in California to test for other possible factors, such as whether a species lives to breed for multiple seasons or just one. But no other factor explained why flower size-number tradeoffs are so hard to spot.

"If you don't account for overall size differences between the species you're comparing, the flower size-number tradeoff is likely to be masked," Maherali said.

The findings appear in the International Journal of Plant Sciences.

]]> Wed, 08 FEB 2012 08:56:32 AEST Kingston RI (SPX) Feb 07, 2012 - A University of Rhode Island biologist who released lizards on tiny uninhabited islands in the Bahamas has shed light on the interaction between evolutionary processes that are seldom observed.

Jason Kolbe, a URI assistant professor of biological sciences, and colleagues from Duke University, Harvard University and the University of California at Davis, found that the lizards' genetic and morphological traits were determined by both natural selection and a phenomenon called founder effects, which occur when species colonize new territory.

Their research was published in the journal Science.

"We rarely observe founder effects as they happen in nature, but we know that it happens because islands are colonized by new species over time," said Kolbe.

"What we didn't know was how these evolutionary mechanisms interact with each other. What we learned is that the differences caused by the founder effects persist even as populations adapt to their new environments."

The founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It often results in the new population becoming genetically or morphologically different from the original population.

The scientists randomly collected brown anole lizards from a large island near Great Abaco and released one pair on each of seven nearby islands whose lizard populations had been cleared by a recent hurricane. The source island is forested while the other islands have short, scrub vegetation.

Previous research found that anoles living in forests had longer hind limbs than those found in scrub habitat. Lizards with longer limbs can run faster on the broad perches available in forests, while short-limbed lizards are more adept at moving on the narrower perches found in lower vegetation.

The scientists revisited each of the islands over the next four years to measure the lizards' limb length and collect tissue samples for genetic analysis. All of the new populations survived and increased an average of 13-fold in the first two years before leveling off.

"We noticed a founder effect one year after starting the experiment, which resulted in differences among the lizards on the seven islands," Kolbe said. "Some of the islands had lizards with longer limbs and some had lizards with shorter limbs, but that was random with respect to the vegetation on the new islands."

Because the structure of the vegetation on the islands differed from that of the source island, the scientists predicted that natural selection would lead the lizards to develop shorter limbs.

"Over the next four years, the lizards on all the islands experienced a decrease in leg length that is attributable to natural selection," Kolbe explained.

"But those that started out with the longest hind limbs still had the longest hind limbs. The fact that the populations maintained their order from longest to shortest limbs throughout the experiment means that both founder effects and natural selection contributed to their current differences."

According to Kolbe, founding effects are rarely observed in nature, with most previous studies being conducted in the laboratory.

"Ours is the first to study this process experimentally in a natural setting, and we were able to account for multiple evolutionary mechanisms through time," he said. "We manipulated the founding of these islands, but everything else about it was natural."

The next step in the research will be to determine how long the founder effects persist before other factors erase its signature.

]]> Wed, 08 FEB 2012 08:56:32 AEST Washington DC (SPX) Feb 07, 2012 - While researchers have long known of the incredible strength of spider silk, the robust nature of the tiny filaments cannot alone explain how webs survive multiple tears and winds that exceed hurricane strength.

Now, a study that combines experimental observations of spider webs with complex computer simulations has shown that web durability depends not only on silk strength, but on how the overall web design compensates for damage and the response of individual strands to continuously varying stresses.

Reporting in the cover story of the Feb. 2, 2012, issue of Nature, researchers from the Massachusetts Institute of Technology (MIT) and the Politecnico di Torino in Italy show how spider web-design localizes strain and damage, preserving the web as a whole.

"Multiple research groups have investigated the complex, hierarchical structure of spider silk and its amazing strength, extensibility, and toughness," says Markus Buehler, associate professor of civil and environmental engineering at MIT.

"But, while we understand the peculiar behavior of dragline silk from the 'nanoscale up'-initially stiff, then softening, then stiffening again-we have little insight into how the molecular structure of silk uniquely improves the performance of a web."

The spider webs found in gardens and garages are made from multiple silk types, but viscid silk and dragline silk are most critical to the integrity of the web. Viscid silk is stretchy, wet and sticky, and it is the silk that winds out in increasing spirals from the web center.

Its primary function is to capture prey. Dragline silk is stiff and dry, and it serves as the threads that radiate out from a web's center, providing structural support. Dragline silk is crucial to the mechanical behavior of the web.

Some of Buehler's earlier work showed that dragline silk is composed of a suite of proteins with a unique molecular structure that lends both strength and flexibility. "While the strength and toughness of silk has been touted before-it is stronger than steel and tougher than Kevlar by weight-the advantages of silk within a web, beyond such measures, has been unknown," Buehler adds.

The common spiders represented in the recent study-including orb weavers (Nephila clavipes), garden spiders (Araneus diadematus) and others-craft familiar, spiraling web patterns atop a scaffolding of radiating filaments. Building each web takes energy the spider cannot afford to expend often, so durability is key to the arachnid's survival.

Through a series of computer models matched to laboratory experiments with spider webs, the researchers were able to tease apart what factors play what role in helping a web endure natural threats that are either localized (such as a twig falling on a filament) or distributed (such as high winds).

"For our models, we used a molecular dynamics framework in which we scaled up the molecular behavior of silk threads to the macroscopic world. This allowed us to investigate different load cases on the web, but more importantly, it also allowed us to trace and visualize how the web fractured under extreme loading conditions," says Anna Tarakanova, who developed the computer models along with Steven Cranford, both graduate students in Buehler's laboratory.

"Through computer modeling of the web," Cranford adds, "we were able to efficiently create 'synthetic' webs, constructed out of virtual silks that resembled more typical engineering materials such as those that are linear elastic (like many ceramics) and elastic-plastic materials (which behave like many metals). With the models, we could make comparisons between the modeled web's performance and the performance seen in the webs made from natural silk. In addition, we could analyze the web in terms of energy, and details of the local stress and strain," which are traits experiments were able to reveal.

The study showed that, as one might expect, when any part of a web is perturbed, the whole web reacts. Such sensitivity is what alerts a spider to the struggling of a trapped insect. However, the radial and spiral filaments each play different roles in attenuating motion, and when stresses are particularly harsh, they are sacrificed so that the entire web may survive.

"The concept of selective, localized failure for spider webs is interesting since it is a distinct departure from the structural principles that seem to be in play for many biological materials and components," adds Dennis Carter, the NSF program director for biomechanics and mechanobiology who helped support the study.

"For example, the distributed material components in bone spread stress broadly, adding strength. There is no 'wasted' material, minimizing the weight of the structure. While all of the bone is being used to resist force, bone everywhere along the structure tends to be damaged prior to failure."

In contrast, a spider's web is organized to sacrifice local areas so that failure will not prevent the remaining web from functioning, even if in a diminished capacity, says Carter. "This is a clever strategy when the alternative is having to make an entire, new web!," he adds. "As Buehler suggests, engineers can learn from nature and adapt the design strategies that are most appropriate for specific applications."

Specifically, when a radial filament in a web is snagged, the web deforms more than when a relatively compliant spiral filament is caught. However, when either type fails-under great stress-it is the only filament to fail.

The unique nature of the spider-silk proteins enhances that effect. When a filament is pulled, the silk's unique molecular structure-a combination of amorphous proteins and ordered, nanoscale crystals-unfurls as stress increases, leading to a stretching effect that has four distinct phases: an initial, linear tugging; a drawn out stretching as the proteins unfold; a stiffening phase that absorbs the greatest amount of force; and then a final, stick-slip phase before the silk breaks.

According to the researchers' findings, the failure of silk threads occurs at points where the filament is disturbed by that external force, but after failure, the web returns to stability - even in simulations using broad forces, like hurricane-force winds.

"Engineered structures are typically designed to withstand large loads with limited damage - but extreme loads are more difficult to account for," says Cranford. "The spider has uniquely solved this problem by allowing a sacrificial member to fail under high load. One of the first questions a structural engineer must ask is 'What is the design load?' For a spider web, however, it doesn't matter if the load is just strong enough to cause failure, or one hundred times higher - the net effect is the same. Allowing a sacrificial member to fail removes the unpredictability of 'extreme' loads from the design equation."

]]> Wed, 08 FEB 2012 08:56:32 AEST St. Louis MO (SPX) Feb 07, 2012 - Today's alarmingly high rate of plant extinction necessitates an increased understanding of the world's biodiversity. An estimated 15 to 30 percent of the world's flowering plants have yet to be discovered, making efficiency an integral function of future botanical research-but how is this best accomplished?

Botanist Dr. Gerrit Davidse, John S. Lehmann Curator of Grasses at the Missouri Botanical Garden in St. Louis has collaborated with eight British botanists to quantify the role of plant collectors in the discovery of plant diversity.

Their findings show a disproportionately high percentage of the world's plant discoveries have been made by just two percent of the world's most prolific and experienced collectors, implying that identifying and funding this small number of experts in the right geographic locations is vital to any effective strategy to document the world's flora. The study was published Wednesday in the British scientific journal "Proceedings of the Royal Society B" (Proc. R. Soc. B.).

"The Global Strategy for Plant Conservation set forth by the Convention on Biological Diversity has outlined its target of a complete online world flora by 2020," said Dr. Bob Magill, senior vice president of science and conservation at the Missouri Botanical Garden. "The conclusion of this study can provide framework for the botanical community as to how we go about achieving this incredibly important goal."

Scientists are increasingly reliant on electronic databases to communicate globally about the extensive amounts of plant specimen data that have been amassed. These central repositories of data have afforded scientists the opportunity to raise novel questions that were not possible before, exploring the dynamics of plant collecting in relation to our knowledge of how new plant species are discovered.

The study looked at four datasets from some of the world's major plant collections-the Missouri Botanical Garden, Royal Botanic Garden Edinburgh, Royal Botanic Gardens Melbourne and The Natural History Museum, London-and in all four instances found a huge difference in the distribution of types of specimens discovered by plant collectors.

Roughly two percent of plant collectors were responsible for half of all types of specimens discovered, while approximately half of all plant collectors had each contributed only a single type of specimen. While this pattern has become slightly less marked in recent years, it is nonetheless remarkable for having persisted so strongly over time.

Closer examination of prolific plant collectors outlines a number of significant traits possessed by the group. The number of plant species discovered increases with the years of collection experience; the median number of species discovered per year by plant collectors active for less than a decade was just one, compared with nine to 18 species for collectors active for a decade or more.

However, this increase in efficiency with experience is not correlated to the length of time actually spent in the field. The rate of species discovery for these prolific plant collectors actually decreases over the duration of collection activity; that is, they discover more in a shorter amount of time.

Geography also plays a part in explaining the success of prolific plant collectors. Although these experienced researchers tend to visit more countries, the vast majority of their plant species discoveries come from a single country. This cannot be attributed to their unique focus on a country with high plant diversity, as prolific collectors were no more likely to collect from highly diverse countries than other, less prolific collectors.

Prolific plant collectors are typically generalists, although the most new species come from their most-collected families. However, a few collectors are highly specialized in the plants of a single family: Carl Luer of the Missouri Botanical Garden, an orchid specialist responsible for hundreds of species of orchids, is a notable example.

Prolific collectors also show a significant increase in their discoveries towards the end of their careers. Most specialize on a particular country, which leads to an increased knowledge of the flora in a particular area. The more years they collect plants, the better and faster they become at collecting new species.

This observation highlights the critical role of the expertise gained from many years in the field. Experienced collectors many not collect as large a quantity of plants as novice collectors, but their accumulated botanical knowledge provides them with the skill to be selective, thus increasing the number of new species found.

Plant collecting is a specific part of the three-step process of plant species discovery (collection, recognition and publication), and as the numbers of professional taxonomists who classify plants decline, there has been a massive increase in the utilization of non-professionals to aid in this work.

This study suggests that as science pushes for more rapid documentation of the world's flora, policy makers and funders must examine how best to develop the experience and skills of selected individuals to catalog undiscovered plants more efficiently.

"One way for institutions to encourage the development of these skills is in performance evaluations, rewarding effective field work on an equal footing with number of papers published and grants obtained," notes Davidse.

Today, 153 years after opening, the Missouri Botanical Garden is a National Historic Landmark and a center for science, conservation, education and horticultural display. With scientists working in 35 countries on six continents around the globe, the Missouri Botanical Garden has one of the three largest plant science programs in the world and a mission "to discover and share knowledge about plants and their environment in order to preserve and enrich life."

]]> Wed, 08 FEB 2012 08:56:32 AEST Durham NC (SPX) Feb 07, 2012 - Biologists who released lizards on tiny uninhabited islands in the Bahamas have uncovered a seldom-observed interaction between evolutionary processes.

Jason Kolbe, a biologist at the University of Rhode Island (URI)--along with colleagues at Duke University, Harvard University and the University of California, Davis--found that the lizards' genetic and morphological (form and structural) traits were determined by both natural selection and a phenomenon called the founder effect.

Their research results are published online in the journal Science.

The founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It often results in the new population becoming genetically or morphologically different from the original population.

"We rarely observe the founder effect as it happens in nature, but we know that it occurs because islands are colonized by new species over time," said Kolbe.

"What we didn't know was how these evolutionary mechanisms [natural selection and the founder effect] interact with each other."

The scientists learned that differences caused by the founder effect persist even as populations adapt to new environments.

"Evolutionary biologists have been debating the importance of founder effects for more than 70 years," said Sam Scheiner, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research.

"This study is the first to definitively demonstrate those effects for ecologically important traits."

Kolbe and colleagues randomly collected brown anole lizards from a large island near Great Abaco in the Bahamas, and released one pair on each of seven nearby islands whose lizard populations had been cleared by a recent hurricane.

The source island is forested, while the other islands have short, scrubby vegetation.

Previous research had found that anole lizards living in forests had longer hind limbs than those found in scrub habitat.

Lizards with longer limbs can run faster on the broad perches available in forests, while short-limbed lizards are more adept at moving on the narrower perches found in lower vegetation.

The scientists revisited each of the islands over the next four years to measure the lizards' limb length and collect tissue samples for genetic analysis.

All the new populations survived and increased an average of 13-fold in the first two years, before leveling off.

"We noticed a founder effect one year after starting the experiment, which resulted in differences among the lizards on the seven islands," Kolbe said.

"Some of the islands had lizards with longer limbs and some had lizards with shorter limbs, but that was random with respect to the vegetation on the new islands."

Because the structure of the vegetation on the islands differed from that of the source island, the scientists predicted that natural selection would lead the lizards to develop shorter limbs.

"Over the next four years, the lizards on all the islands experienced a decrease in leg length that is attributable to natural selection," Kolbe explained. "But those that started out with the longest hind limbs still had the longest hind limbs."

The fact that the populations maintained their order from longest to shortest limbs throughout the experiment means that both the founder effect and natural selection contributed to their current differences.

According to Kolbe, the founder effect is rarely observed in nature, with most previous research conducted in the laboratory.

"Ours is the first to study this process experimentally in a natural setting, and we were able to account for multiple evolutionary mechanisms through time," he said. "We manipulated the founding of these islands, but everything else about it was natural."

The next step in the research will be to determine how long the founder effect persists before other factors erase its signature.

Co-authors of the paper are Kolbe; Manuel Leal of Duke University; Thomas Schoener and David Spiller of the University of California, Davis; and Jonathan Losos of Harvard.

The study was also funded by the National Geographic Society.

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