Neon Blue-tailed Tree Lizard Glides Like A Feather, Thanks To Light Bubbly Bones

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ScienceDaily (July 22, 2009) — Most lacertid lizards are content scurrying in and out of nooks and crannies in walls and between rocks. However, some have opted for an arboreal life style. Neon blue tailed tree lizards (Holaspis guentheri) leap from branch to branch as they scamper through trees in the African forest. There are even anecdotes that the tiny African tree lizards can glide. But without any obvious adaptations to help them to upgrade a leap to a glide, it wasn't clear whether the reptiles really do take to the air and, if they do, how they remain aloft.

Intrigued by all aspects of lacertid locomotion, Bieke Vanhooydonck from the University of Antwerp and her colleagues, Anthony Herrel and Peter Aerts, decided to find out whether neon blue tailed tree lizards really glide. Recruiting undergraduate Greet Meulepas to the team, they began filming dainty neon blue tailed tree lizards, gliding geckos (Ptychozoon kuhli) and the common wall lizard (Podarcis muralis) as the animals leapt from a 2m high platform to see if the neon blue tailed tree lizards really could glide. Vanhooydonck and her colleagues publish their discovery that H. guentheri glide like feathers on 17 July 2009 in the Journal of Experimental Biology.
Unfortunately, filming the lizards was extremely difficult. Having startled the small animals into leaping off the platform, the team had little control over the animal's direction, and couldn't guarantee that it was parallel to their camera. It was also difficult to capture each trajectory with a single camera and tricky to get the lighting conditions right. But after weeks of persistence the team finally collected enough film, as the lizards leapt, to compare their performances.
At first, it didn't look as if the African lizard was gliding any better than the common wall lizard. Both animals were able to cover horizontal distances of 0.5m after leaping from the platform, while the gliding gecko covered distances greater than 1 m, aided by its webbed feet and skin flaps. But when the team compared the lizards' sizes, they noticed that there was a big difference between the common wall lizard and the tree lizard. The tiny tree lizard only weighed 1.5 g, almost 1/3 of the larger common wall lizard's weight and 1/10 the gliding gecko's mass, so Aerts calculated how far each lizard would travel horizontally if they fell like a stone. This time it was clear that the tiny tree lizard was travelling 0.2m further than Aerts would have expected if it were simply jumping off the platform. The tree lizard was definitely delaying its descent and landing more slowly than the common wall lizard; the tree lizard was gliding.
But how was the tiny tree lizard able to remain airborne for so long? Maybe the lizard was squashing itself flat while gliding to increase its surface area and generate more lift. But when the team analysed the lizards' trajectories, the tree lizard's shape did not change. And when Aerts calculated the amount of lift each lizard generated as they descended, it was clear that the tree lizard was unable to produce a lift force. The team realised that instead of increasing its surface area to generate lift, the tree lizard is able to glide because it is so light. The tree lizard's 'wing loading' (mass:surface area ratio) was the same as that of the gliding gecko (assisted by skin flaps and webbed feet) so the tree lizard was able to glide like a feather because it was so light.
Curious to find out why the tree lizard is so light, Herrel contacted Renaud Boistel, Paul Tafforeau and Vincent Fernandez at the European Synchrotron Radiation Facility to scan all three lizards' bodies. Visualising the animals' skeletons with X-rays, it was clear that the tree lizard's bones were packed full of air spaces, making the lizard's skeleton feather light for gliding.
Journal reference:
Vanhooydonck, B., Meulepas, G., Herrel, A., Boistel, R., Tafforeau, P., Fernandez, V. and Aerts, P. Ecomorphological analysis of aerial performance in a non-specialized lacertid lizard, Holaspis guentheri. J. Exp. Biol., 212, 2475-2482
Adapted from materials provided by Journal of Experimental Biology, via EurekAlert!, a service of AAAS. Original article written by Kathryn Knight.

King Crabs Go Deep To Avoid Hot Water

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ScienceDaily (July 19, 2009) — Researchers from the University of Southampton have drawn together 200 years' worth of oceanographic knowledge to investigate the distribution of a notorious deep-sea giant - the king crab. The results, published this week in the Journal of Biogeography, reveal temperature as a driving force behind the divergence of a major seafloor predator; globally, and over tens of millions of years of Earth's history.

In deep seas all over the world, around 100 species of king crabs live largely undiscovered. The fraction that have been found includes some weird and wonderful examples - Paralomis seagrantii has its eight walking legs and claws entirely covered in long fur-like setae; while related group Lithodes megacanthus grows to lengths of 1.5 metres, and has 15-20-cm long defensive spines covering its body. At temperatures of around 1- 4ºC, these crabs thrive in some of the colder waters on Earth; living and growing very slowly, probably to very old ages. Only in the cooler water towards the poles are king crabs found near the water surface - though temperatures found around some parts of the Antarctic (below 1ºC) are too extreme for their survival.
A paper, published 15 years ago in Nature is thought to show that king crabs evolved from shell-bound hermit crabs - similar to the familiar shoreline animals. Soft-bodied, but shell-free intermediate forms are found only in the shallow waters off Japan, Alaska, and Western Canada.
By looking at 200 years' worth of records from scientific cruises and museum collections, Sally Hall and Dr Sven Thatje from the University of Southampton's School of Ocean and Earth Science at the National Oceanography Centre, Southampton discovered that the soft-bodied forms can live at temperatures about ten degrees higher than the hard-bodied forms, but that both groups can only reproduce when temperature is between 1ºC up to 13-15ºC.
"It seems that most shallow-water representatives of this family are trapped in the coastal regions of the North Pacific because the higher sea surface temperatures further south prevent them from reproducing successfully and spreading," said Dr Thatje.
In order to leave this geographic bottleneck and spread around the world, the shallow water ancestors of current deep-sea groups had to go deep and adapt to the challenges of life in the deep sea. The process of adaptation to constant low temperatures (1-4ºC) prevailing in the deep sea seems to have narrowed the temperature tolerance range of the crabs where they have emerged to the surface waters in the Southern Hemisphere. With differences of only a couple of degrees in temperature affecting the distribution of the king crab, it is difficult to predict the consequences of range expansion in the warming waters around the Antarctic Peninsular region.
King crabs are of great commercial value, and fisheries are established in high latitude regions of both hemispheres. "Understanding their evolutionary history and ecology is key to supporting sustainable fisheries of these creatures," said research student Sally Hall. She adds: "Recent range extensions of king crabs into Antarctica, as well as that of the red king crab Paralithodes camtchaticus in the Barents Sea and along the coast off Norway emphasise the responsiveness of this group to rapid climate change."
This study reveals temperature as a driving force behind the speciation and radiation of a major seafloor predator globally and over tens of millions of years of Earth's history.
The study has been supported by the National Environment Research Council (UK) through a PhD studentship to Sally Hall, and a Research Grant from the Royal Society awarded to Dr Thatje.
Adapted from materials provided by University of Southampton.

Reintroduced Chinese Alligators Now Multiplying In The Wild In China

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ScienceDaily (July 18, 2009) — The Wildlife Conservation Society announced today that critically endangered alligators in China have a new chance for survival. The WCS's Bronx Zoo, in partnership with two other North American parks and the Department of Wildlife Conservation and Management of the State Forestry Administration of China, has successfully reintroduced alligators into the wild that are now multiplying on their own.

The alligator hatchlings—15 in number—are the offspring of a group of alligators that includes animals from the Wildlife Conservation Society's Bronx Zoo. The baby alligators represent a milestone for the 10-year effort to reintroduce the Chinese alligator on Chongming Island, located at the mouth of China's Yangtze River.
The announcement was made at the International Congress for Conservation Biology, convened by the Society for Conservation Biology in Beijing, China (July 11-16).
"We are grateful to our Chinese partners for their commitment to reintroduce Chinese alligators back into the wild," said Dr. Steven E. Sanderson, President and CEO of the Wildlife Conservation Society. "WCS has championed careful wildlife reintroductions for more than a century. The reintroduction of Chinese alligators is a great example of how WCS partners with governments and local communities around the world to save wildlife and wild places."
"This is fantastic news," said WCS researcher Dr. John Thorbjarnarson, one of the world's foremost experts on crocodilians and a participant in the project. "The success of this small population suggests that there's hope for bringing the Chinese alligator back to some parts of its former distribution."
Plans to reintroduce Chinese alligators started in 1999 with a survey conducted by WCS, the Anhui Forestry Bureau, and the East China Normal University in Anhui Province, the only remaining location where the reptiles are still found in the wild in what is a small fraction of the alligator's former range. The results of the survey were dire, with an estimate of fewer than 130 animals in a declining population.
An international workshop on the species was held in 2001, followed by recommendations for the reintroduction of captive bred alligators. The first three animals released in Hongxing Reserve of Xuancheng County in Anhui in 2003 were from the Anhui Research Center of Chinese Alligator Reproduction (ARCCAR).
To ensure the maximum genetic diversity for the effort, project participants imported 12 more animals to Changxing Yinjiabian Chinese Alligator Nature Reserve from North America, including four from the Bronx Zoo. From this group, three animals from the U.S. were released in 2007 along with three more alligators from Changxing. The alligators were given health examinations by veterinary professionals from WCS's Global Health Program and the Shanghai Wildlife Zoo and fitted with radio transmitters for remote monitoring before being released.
Experts reported that the reintroduced alligators successfully hibernated, and then in 2008, bred in the wild.
With a former range that covered a wide watershed area of East China, the Chinese alligator—or "tu long," which means "muddy dragon"—is now listed as "Critically Endangered" on IUCN's Red List of Threatened Species and is the most threatened of the 23 species of crocodilians in the world today. It is one of only two alligator species in existence (the other is the better known, and much better off, American alligator).
The Yangtze River, where the reintroduction of these alligators took place, is the third longest river in the world (after the Amazon and the Nile) and is China's most economically important waterway. The world's largest hydro-electric dam—the Three Gorges Dam—is also located on the river. The high levels of development along the river have become a challenge for native wildlife; in 2006, a comprehensive search for the Yangtze River dolphin, or baiji, didn't find any, although one isolated sighting of a dolphin was made in 2007.
Other participants in the project include the East China Normal University, Shanghai Forestry Bureau, Changxing Yinjiabian Chinese Alligator Nature Reserve, and Wetland Park of Shanghai Industrial Investment (Holdings) Co. Ltd.
The project is being supported by the Ocean Park Conservation Foundation, Hong Kong.
Adapted from materials provided by Wildlife Conservation Society.

Evolutionary Event Underlying Origin Of Dachshunds, Dogs With Short Legs, Discovered

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ScienceDaily (July 17, 2009) — A single evolutionary event appears to explain the short, curved legs that characterize all of today's dachshunds, corgis, basset hounds and at least 16 other breeds of dogs, a team led by the National Human Genome Research Institute (NHGRI), part of the National Institutes of Health, reported July 16. In addition to what it reveals about short-legged dogs, the unexpected discovery provides new clues about how physical differences may arise within species and suggests new approaches to understanding a form of human dwarfism.

In a study published in the advance online edition of the journal Science, the researchers led by NHGRI's Elaine Ostrander, Ph.D., examined DNA samples from 835 dogs, including 95 with short legs. Their survey of more than 40,000 markers of DNA variation uncovered a genetic signature exclusive to short-legged breeds. Through follow-up DNA sequencing and computational analyses, the researchers determined the dogs' disproportionately short limbs can be traced to one mutational event in the canine genome — a DNA insertion — that occurred early in the evolution of domestic dogs.
"Every species, including canine and human, carries an amazing record of evolution scripted in its genome that can teach us about the mechanisms at work in biology, as well as about human health and disease," said NHGRI Scientific Director Eric Green, M.D., Ph.D. "This work provides surprising evidence of a new way in which genome evolution may serve to generate diversity within a species."
Specifically, the researchers found that in contrast to other dog breeds, all short-legged dog breeds have an extra copy of the gene that codes for a growth-promoting protein called fibroblast growth factor 4 (FGF4). Although functional, the extra gene lacks certain parts of the DNA code, called introns, found in normal genes. These characteristics led researchers to conclude that the extra gene is a so-called retrogene that was inserted into the dog genome some time after the ancestor of modern dog breeds diverged from wolves.
To understand retrogenes, one first needs to understand how the cell normally makes proteins. To produce a protein, a gene's DNA code is transcribed into a molecule called messenger RNA (mRNA). The mRNA then leaves the cell's nucleus and enters the outer region of the cell, called the cytoplasm. There the mRNA is read by tiny molecular machines, called ribosomes, which use the information to assemble proteins.
Retrogenes are formed when the mRNA encounters something — often a type of virus called a retrovirus — that turns it back into DNA through a process referred to as reverse transcription. This new piece of DNA, which contains the same protein-coding information as the gene that produced the mRNA, may then be inserted back into the genome, usually at a much different place than the original gene. Depending on where it is inserted, this piece of DNA may or may not be capable of producing proteins. If it is functional, it is called a retrogene.
In the case of short-legged dogs, the inserted retrogene results in the overproduction of the FGF4 protein, which researchers hypothesize may turn on key growth receptors at the wrong times during fetal development. Veterinary researchers already know that in certain dog breeds the development of long bones is curtailed due to calcification of growth plates, resulting in short legs with a curved appearance. The trait, called disproportional dwarfism, or chondrodysplasia, is an American Kennel Club standard for more than a dozen domestic dog breeds, including the dachshund, corgi, Pekingese and basset hound. This trait is distinct from the uniformly miniature size of toy breeds, such as the toy poodle.
"Our findings suggest that retrogenes may play a larger role in evolution than has been previously thought, especially as a source of diversity within species," said the study's first author, Heidi G. Parker, Ph.D. of NHGRI. "We were surprised to find that just one retrogene inserted at one point during the evolution of a species could yield such a dramatic physical trait that has been conserved over time."
In the past, retrogenes have been recognized as an important source of changes that have fueled the divergence of species. However, the dog findings are the first example of a retrogene that has spurred significant and long-lasting variation within a single species.
The findings also may have implications for understanding human biology and disease. Researchers note that some people are affected by a similar appearing growth disorder, called hypochondroplasia, which belongs to a group of conditions commonly referred to as dwarfism. While about two-thirds of cases of human hypochondroplasia have been linked to a different gene, the cause of the other one-third remains a mystery.
"This study points to a new gene that should be investigated for its possible role in human hypochondroplasia," said Dr. Ostrander, the study's senior author and a senior investigator in NHGRI's Division of Intramural Research. "Our findings may prove valuable to scientists studying other aspects of human growth and development. The work also underscores the value of canine studies for uncovering new biological mechanisms that are likely relevant to human disease."
In addition to Ostrander and her colleagues at NHGRI, the team included researchers from Cornell University in Ithaca, N.Y.; the University of California, Los Angeles; Oregon Health and Science University, Portland; the Waltham Center for Pet Nutrition in Leicestershire, England; and Affymetrix Corporation, Santa Clara, Calif.
Adapted from materials provided by NIH/National Human Genome Research Institute.

Not Only Dogs, But Deer, Monkeys And Birds Bark To Deal With Conflict

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ScienceDaily (July 15, 2009) — Biologically speaking, many animals besides dogs bark, according to Kathryn Lord at the University of Massachusetts Amherst, but the evolutionary biologist also says domestic dogs vocalize in this way much more than birds, deer, monkeys and other wild animals that use barks. The reason is related to dogs’ 10,000-year history of hanging around human food refuse dumps, she suggests.

In her recent paper in a special issue of the journal, Behavioural Processes, Lord and co-authors from nearby Hampshire College also provide the scientific literature with its first consistent, functional and acoustically precise definition of this common animal sound.
As Lord, a doctoral candidate in organismic and evolutionary biology at UMass Amherst, explains, “We suggest an alternative hypothesis to one that many biologists seem to accept lately, which seeks to explain dog barking in human-centric terms and define it as an internally motivated vocalization strategy.” In the researchers’ view, however, barking is not a special form of communication between dogs and humans. “What we’re saying is that the domestic dog does not have an intentional message in mind, such as, ‘I want to play’ or ‘the house is on fire,’” explains Lord.
Rather, she and colleagues say barking is the auditory signal associated with an evolved behavior known as mobbing, a cooperative anti-predator response usually initiated by one individual who notices an approaching intruder. A dog barks because she feels an internal conflict―an urge to run plus a strong urge to stand her ground and defend pups, for example. When the group joins in, the barks intimidate the intruder, who often flees.
“We think dogs bark due to this internal conflict and mobbing behavior, but domestic dogs bark more because they are put, and put themselves into, conflicting situations more often,” she says.
The reason traces back to the first dogs that started hanging around human food dumps about 8,000 to 10,000 years ago. They would have experienced a serious disadvantage if they had run a mile away every time a human or other animal approached. As Lord explains, “In evolutionary terms, dogs self-selected the behavior of sticking around, overcoming their fear and being rewarded by getting to eat that meal before some other dog got it. Thus these animals allow people to get unusually close. The scared ones die while those less scared stay, eat, survive and reproduce. So they inherit the tendency.”
She adds, “By contrast, wild animals like wolves have a very long flight distance. They hear something and they run before you’d ever see them. Dogs hang around, but now they have committed to holding their ground and the closer an ‘intruder’ gets, the more likely mobbing is to occur rather than running away.”
An example of the domestic environment (rather than the dog’s own behavior) that increases barking is the animal stuck behind a fence with a person approaching, says Lord. “The dog may either feel anxiety or excitement at seeing a stranger but in either case the dog is prevented from approaching or fleeing. This creates conflict, and thus barking.”
Several technical pages of the researchers’ recent paper identify eight different parameters in three categories which must be met in order to classify a given vocalization as a bark. These include tonality, noise, pitch, volume or amplitude, abrupt onset and pulse duration, for example.
In their view, barking is not self-referential communication to convey a message, but a short, loud sound characterized by combining both noise and tonal sounds, which is unusual in animal calls. This definition widens the bark’s usefulness as a functional behavior seen in many animals, though domesticated dogs display it more often. “Using this definition, even birds bark, and certainly many mammals besides canines, including baboons and monkeys, rodents and deer also bark,” Lord explains. “In a whole bunch of mammals and birds, what they do in such conflicted situations is bark.”
This evolutionary view of barking does not sit well with some pet owners who insist that Buffy communicates with them by barking, the researchers acknowledge. “We understand the objection when people say their dogs bark for supper or to get out and play,” Lord says. “Dogs do quickly learn the simple cause-and-effect relationship between their bark at 10 p.m. and the fact that you’ll get right up and take them outdoors. It’s true, but in our view it’s going too far to suggest the animal is intentionally referring to a specific activity. Rather, it has just learned cues, as it does when it learns to sit or beg for a treat.”
Adapted from materials provided by University of Massachusetts Amherst.

Bee Colony Collapse Disorder: New Bait Lures Varroa Mite To Its Doom

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ScienceDaily (July 15, 2009) — Varroa mites could literally be walking into a trap—thanks to a new attractant developed by Agricultural Research Service (ARS) scientists in Gainesville, Fla.

The 1/16-inch long parasite, Varroa destructor, is a top pest of honey bees nationwide, hindering the beneficial insects' ability to pollinate almonds, blueberries, apples, zucchini and many other flowering crops.
At the ARS Chemistry Research Unit in Gainesville, research leader Peter Teal and colleagues are testing a bait-and-kill approach using sticky boards and natural chemical attractants called semiochemicals.
In nature, Varroa mites rely on these semiochemicals to locate—and then feed on—the bloodlike hemolymph of both adult honey bees and their brood. Severe infestations can decimate an affected hive within several months—and rob the beekeeper of profits from honey or pollinating services. But in this case, the mites encounter a more heady bouquet of honey bee odors that lure the parasites away from their intended hosts and onto the sticky boards, where they starve.
In preliminary tests, 35 to 50 percent of mites dropped off the bees when exposed to the attractants. Free-roving mites found the semiochemicals even more attractive, according to Teal.
Moreover, the extra dose of semiochemicals wafting through hives didn't appear to significantly interfere with the honey bees' normal behavior or activity, added Teal who, along with postdoctoral associate Adrian Duehl and University of Florida collaborator Mark Carroll, reported the results this past January at the 2009 North American Beekeeping Conference in Reno, Nev.
The team hopes ARS' patenting of the Varroa mite attractants will encourage an industrial partner to develop the technology further.
Adapted from materials provided by USDA/Agricultural Research Service.

Water Snake Startles Fish So They Flee Into Its Jaws

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ScienceDaily (July 14, 2009) — Forget the old folk tales about snakes hypnotizing their prey. The tentacled snake from South East Asia has developed a more effective technique. The small water snake has found a way to startle its prey so that the fish turn toward the snake's head to flee instead of turning away. In addition, the fish's reaction is so predictable that the snake actually aims its strike at the position where the fish's head will be instead of tracking its actual movement.

"I haven't been able to find reports of any other predators that exhibit a similar ability to influence and predict the future behavior of their prey," says Kenneth Catania, associate professor of biological sciences at Vanderbilt University, who has used high-speed video to deconstruct the snake's unusual hunting technique.
His observations are published the week of June 15 in the online early edition of the Proceedings of the National Academy of Sciences.
Catania, who is the recipient of a MacArthur "genius" award, studies the brains and behavior of species with extreme specializations. He was attracted to the tentacled snake because it is the only snake that comes equipped with a pair of short tentacles on its nose and he was curious about their function.
"Before I begin a study on a new species, it is my practice to spend some time simply observing its basic behavior," Catania explains. The snake forms an unusual "J" shape with its head at the bottom of the "J" when it is fishing. Then it remains completely motionless until a fish swims into the area near the hook of the "J." That is when the snake strikes.
The snakes' motions take only a few hundredths of a second and are too fast for the human eye to follow. However, its prey reacts even faster, in a few thousandths of a second. In fact, fish are famous for the rapidity of their escape response and it has been extensively studied. These studies have found that many fish have a special circuit in their brains that initiates the escape, which biologists call the "C-start." Fish ears sense the sound pressure on each side of their body. When the ear on one side detects a disturbance, it sends a message to the fishes' muscles causing its body to bend into a C-shape facing in the opposite direction so it can begin swimming away from danger as quickly as possible.
Catania is the first scientist to study this particular predator-prey interaction with the aid of a high-speed video camera. When he began examining the movements of the snake and its prey in slow motion, he saw something peculiar. When the fish that the snake targets turn to flee, most of them turn toward the snake's head and many literally swim into its jaws! In 120 trials with four different snakes, in fact, he discovered that an amazing 78 percent of the fish turned toward the snake's head instead of turning away.
Next, the biologist noticed that the first part of its body that the snake moves is not its head. Instead, it flexes a point midway down its body. Using a sensitive hydrophone that he put in the aquarium, he confirmed that this body fake produces sound waves intense enough to trigger the fish's C-start response. Because these sound waves come from the side opposite the snake's head, this reflex action drives the fish to turn and swim directly toward the snake's mouth.
"Once the C-start begins, the fish can't turn back," Catania says. "The snake has found a way to use the fish's escape reflex to its advantage."
As he studied the snake's actions even closer, he made an even more remarkable discovery. When it strikes, the snake doesn't aim for the fish's initial position and then adjust its direction as the fish moves – the way most predators do. Instead it heads directly for the location where it expects the fish's head to be.
"The best evidence for this is the cases when the snake misses," says Catania. "Not all the targeted fish react with a C-start and the snake almost always misses those that don't react reflexively."
Catania's next step will be to determine whether this predictive capability is hard-wired or learned. To do so, he hopes to obtain some baby snakes that have just hatched and videotape their first efforts to catch prey.
The research was supported by a grant from the National Science Foundation.
Adapted from materials provided by Vanderbilt University.

Fire Ant Outcompetes Other Species, Even In Its Native Habitat

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ScienceDaily (July 14, 2009) — Even in its native Argentina, the fire ant wins in head-to-head competition with other ant species more than three-quarters of the time, according to Agricultural Research Service (ARS) scientists.

ARS scientists at the South American Biological Control Laboratory (SABCL) in Hurlingham, Argentina, have been studying how different ant species fare against the fire ant as part of an effort to learn more about the behavior of this pest—an invasive species in its non-native United States.
Fire ants often attack in swarms--not only causing painful stings to humans, but can even kill small animals. Little has been known, however, about the fire ant's competitive nature or how it interacts with other ants.
SABCL biologist Luis Calcaterra, working closely with lab director Juan Briano, has been studying interactions between the red imported fire ant, Solenopsis invicta, and other aboveground foraging ants in two habitats in northeastern Argentina—using a combination of pitfall traps and baits to study day-to-day activity in ant communities.
The pitfall trap is a 50 milliliter plastic tube buried in the ground and half-filled with soapy water. The bait is one gram of canned tuna placed on a plastic card measuring five centimeters in diameter. The trap and bait gave the scientists a way to determine ant populations at the sites, and showed the dominance of each species.
Some 28 ant species coexisted with S. invicta in an open area of forest growing along a watercourse, whereas only 10 species coexisted with S. invicta in the dry forest grassland. The researchers found that the fire ants had the highest numbers in the open forest area along the watercourse.
Prior to these studies, it was thought that the fire ant—now established throughout the Americas—was not dominant in its native land. But the studies showed that the fire ants were the most ecologically dominant, winning 78 percent of the interactions with other ants, mostly against its most frequent competitor, the South American big-headed ant, Pheidole obscurithorax, an ant of northern Argentina and Paraguay also introduced in the United States. And in battles with the invasive Argentine ant, Linepithema humile, the fire ants were even more dominant, winning out 80 percent of the time.
This study was published in Oecologia, a journal that deals with plant and animal ecology.
Adapted from materials provided by USDA/Agricultural Research Service.

Darwin’s Mystery Of Appearance Of Flowering Plants Explained

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ScienceDaily (July 14, 2009) — The appearance of many species of flowering plants on Earth, and especially their relatively rapid dissemination during the Cretaceous (approximately 100 million years ago) can be attributed to their capacity to transform the world to their own needs.

In an article in Ecology Letters, Wageningen ecologists Frank Berendse and Marten Scheffer postulate that flowering plants changed the conditions during the Cretaceous period to suit themselves. The researchers have consequently provided an entirely new explanation for what Charles Darwin considered to be one of the greatest mysteries with which he was confronted.
During the Cretaceous, the Earth's surface underwent one of its greatest changes in vegetation composition, a change which also took place with unprecedented speed. Frank Berendse (Professor of Nature Conservation and Plant Ecology), and Marten Scheffer, (Professor of Aquatic Ecology), both at Wageningen University, wanted to understand how this happened. They looked for the explanation in a totally unconventional direction.
Before the early Cretaceous, the vegetation consisted primarily of gymnosperms and ferns. These plants were largely replaced by an entirely new group of plants: the angiosperms (flowering plants). During the early Cretaceous – approximately 125 million years ago – the first flowering plants evolved. Soon thereafter, the gymnosperms in the tropics were replaced almost entirely by the angiosperms. And by the end of the Cretaceous (65 million years ago), the empire of the flowering plants had become definitively established in much of the rest of the world. The gymnosperms continued to exist only in the far north – which is the case even today.
The rapid increase in the fantastic diversity of flowering plants – linked to their rapid conquest of the Earth – was one of the greatest puzzles faced by Charles Darwin. In a letter to Joseph Hooker dated 22 July 1879, he referred to an "abominable mystery". The great diversity of fossil flowering plants from the late Cretaceous, while there were virtually no fossils known from the early Cretaceous, appeared to be completely in conflict with his vision that the emergence of new species could only take place very gradually.
The big question was how this massive change could have taken place with such unprecedented speed. Was it because – just before the Cretaceous – that the big Sauropods were forced out by the much smaller Ornithischian dinosaurs, which then systematically ate all the seedlings of the gymnosperms? Or was it because the flowering plants could evolve simultaneously with many insect species that could pollinate their flowers?
According to Berendse and Scheffer, we must think in a totally different direction. They postulate that the flowering plants were able to change the world to suit their own needs. They grew more rapidly and therefore required more nutrients. In a world that was poor in nutrients and was entirely dominated by the gymnosperms, that kept the soil poor - with their poorly degradable litter - flowering plants had great difficulties to establish. But at some locations where the gymnosperms had temporarily disappeared, for example due to floods, fires or storms, the angiosperms could increase so that they were capable of improving their own conditions with their easily degradable litter.
According to the theory of Berendse and Scheffer, this led to positive feedback; as a result, the flowering plants could increase even more rapidly and were capable of replacing the angiosperms in much of the world. Ultimately, the improved edibility of the leaves and fruits of the flowering plants led to a tremendous increase in the number of plant eaters on the Earth, which opened the way to the rapid evolution of mammals, and finally to the appearance of humans.
Journal reference:
Frank Berendse and Marten Scheffer. The angiosperm radiation revisited, an ecological explanation for Darwin's 'abominable mystery'. Ecology Letters, Published Online: 2 Jul 2009 DOI: 10.1111/j.1461-0248.2009.01342.x
Adapted from materials provided by Wageningen University and Research Centre, via AlphaGalileo.

Scientists Are Learning More About Big Birds From Feathers

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ScienceDaily (July 13, 2009) — Catching adult eagles for research purposes is no easy task, but a Purdue University researcher has found a way around the problem, and, in the process, gathered even more information about the birds without ever laying a hand on one.

"Many birds are small, easy to catch and abundant," said Andrew DeWoody, associate professor of forestry and natural resources. "With eagles, the effort can be 100 to 1,000 times greater than catching chickadees."
Eagles can be hard to find, they often require live bait to attract and, with sharp talons and beaks capable of snapping off human fingers, they pose a risk to their would-be captors.
Instead of catching eagles, DeWoody collects their feathers and uses the small amount of DNA in them to create a tag that corresponds to a particular bird. Those tags can be used to determine population, parentage, roosting patterns and sex ratio.
"In an afternoon, you can go out and pick up hundreds of feathers," DeWoody said, "As field work goes, it's about as easy as it gets."
DeWoody's method is described in a chapter of the Handbook of Nature Conservation: Global and Economic Issues, which was released this week. The chapter is a compilation of his research on the topic.
Most birds are studied by catching them in nets and attaching tracking devices. Researchers can then follow the birds and use radio technology to triangulate their locations.
Eagles and other large birds present several challenges, however, even beyond catching them.
"Eagles will literally fly hundreds of miles in two days," DeWoody said. "They fly in areas where you can't track them in a pickup truck."
Capturing a bird as large as an eagle can often be traumatic to the animal.
"They're wild animals that don't want to be caught," DeWoody said. "They can get hurt as well. Using feathers, you avoid all that."
And costs can be as high as $5,000 for the tracking technology that researchers must attach to eagles, a prohibitive cost if studying more than a few birds.
DeWoody's studies were done in Kazakhstan with imperial eagles, a top predator of international concern because its population is declining.
The feathers give a good picture of recent eagle habits because they do not survive long in Kazakhstan's winters. Any feathers collected after the winter thaw, then, had to have been recently dropped. In one study, DeWoody's team found that an area thought to have about 40 juvenile eagles living in it based on human observation actually had closer to 300.
The work also helped researchers understand more about the roosting habits of some eagles that use a nest for months at a time versus others who float around from roost to roost. Another study showed that DNA could be used to distinguish eagle species from one another, and that imperial, golden and white-tailed eagles often utilized the same roosts at the same time.
The National Geographic Society and the National Birds of Prey Trust funded DeWoody's research.
Journal reference:
Jamie A. Rudnick, Todd E. Katzner and J. Andrew DeWoody. Genetic Analyses of Noninvasively Collected Feathers Can Provide New Insights Into Avian Demography and Behavior. Handbook of Nature Conservation: Global and Economic Issues, 2009
Adapted from materials provided by Purdue University.

Male Seahorses Like Big Mates

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ScienceDaily (July 13, 2009) — Male seahorses have a clear agenda when it comes to selecting a mating partner: to increase their reproductive success. By being choosy and preferring large females, they are likely to have more and bigger eggs, as well as bigger offspring, according to Beat Mattle and Tony Wilson from the Zoological Museum at the University of Zurich in Switzerland.

Seahorses have a unique mode of reproduction: male pregnancy. Male seahorses provide all post-fertilization parental care, yet despite the high levels of paternal investment, they have long been thought to have conventional sex roles, with females choosing mating partners and males competing for their attention. However, clutch, egg and offspring size all increase with female body size in seahorses, suggesting that males may obtain fecundity benefits by mating with large-bodied females.
Mattle and Wilson investigated the mating behavior of the pot-bellied seahorse (Hippocampus abdominalis), concentrating on the importance of partner body size in mate selection. A total of 10 female and 16 male sexually mature seahorses, obtained from a captive breeding facility in
Tasmania, took part in the experiment. Individuals of both sexes were presented with potential mating partners of different sizes. Mating preferences were quantified in terms of time spent courting each potential partner.
Mattle and Wilson found striking differences in courtship behavior between male and female seahorses, with choosy males and indiscriminate females.
Male seahorses were highly active and showed a clear preference for larger partners. In contrast, females were significantly less active and showed ambiguous mating preferences.
The authors conclude: "The strong male preferences for large females demonstrated here suggest that sexual selection may act strongly on female body size in wild populations of H. abdominalis, consistent with predictions on the importance of female body size for reproductive output in this species."
Their findings have just been published online in Springer's journal Behavioral Ecology and Sociobiology.
Adapted from materials provided by Springer Science+Business Media, via AlphaGalileo.

Southern Elephant seals responded rapidly to climate and habitat change.

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ScienceDaily (July 12, 2009) — Southern Elephant seals responded rapidly to climate and habitat change and established a new breeding site thousands of kilometres from existing breeding grounds, according to new research.

An international research team, including post-doctorate Dr Mark de Bruyn and collaborators from the US, South Africa and Italy, led by Professor Rus Hoelzel from the School of Biological and Biomedical Sciences, Durham University, found that when the Antarctic ice sheets of the Ross Sea Embayment retreated in the Holocene period 8,000 years ago, elephant seals, Mirounga leonina, adopted the emergent habitat and established a new population which flourished.
DNA sequences from the ancient remains of seals from the now extinct Antarctic colony showed high levels of genetic diversity, probably due to the very large population size sustained there. The study, published in the academic journal PLoS Genetics, and funded by the US National Science Foundation, shows how environmental change can drive the demographic and evolutionary processes that determine diversity within and among species.
Tracking these processes during periods of change reveals mechanisms for the establishment of populations, and provides predictive data on response to potential future impacts, including those caused by climate change.
Professor Rus Hoelzel said: "In general, this approach of looking to the past to understand what might happen in the future, has good potential for predicting the impact of environmental change in both marine and terrestrial systems.
"We've shown how a highly mobile marine species responded to the gain and loss of new breeding habitat. The new habitat was quickly adopted, probably because seals migrate annually into Antarctic waters to feed. However, when the ice returned and the habitat was lost, only a small proportion returned to the original source population. The Antarctic population crashed and much diversity was lost."
This habitat was released after the retreat of the grounded ice sheet in the Ross Sea Embayment 7,500-8,000 years ago, and is within the range of modern foraging excursions from the Macquarie Island colony. Using ancient mtDNA and evolutionary models, the research team tracked the population dynamics of the now extinct colony and the connectivity between this and modern breeding sites.
The team found clear signs of rapid expansion in the new colony 8,000 years ago. This was followed by directional migration away, coupled with a loss of diversity 1,000 years ago, when the sea ice is thought to have expanded. The data suggest that the new colony seals came initially from Macquarie Island, and that some returned there, but in much smaller numbers, when the new colony habitat was lost 7,000 years later.
In order to understand how biodiversity is generated and maintained over time, the team has set out to understand the process by which the seal populations formed and diverged. They analysed data from ancient DNA to show how elephant seal populations responded when new breeding habitat was gained and then lost over the course of approximately 7,000 years.
Professor Rus Hoelzel said: "Using ancient DNA, we were able to track the dynamics and diversity of a population from its foundation, through to its extinction, in the context of Holocene climate change. We learned that new habitat emerging within the species' migratory range could be quickly taken advantage of, but that the reverse was not true. The movement patterns of seals from this Antarctic breeding site would have been unlikely to take them near other potential breeding sites, and so when their breeding site was lost, their numbers crashed.
"The seals that discovered the new breeding site had things good, because food was abundant and nearby, however when the ice returned, the new colony collapsed and only a few seals made it back to their original home.
"This illustrates the importance of understanding the behaviour and life history of a species, in order to model how it may be able to respond to rapid change."
The key factors in the expansion of the new colony were likely to be the abundant local food resource and extensive physical habitat that allowed rapid expansion after the initial founder event, and a tendency for females to return to annual breeding sites in this species.
When the ice expanded again 1,000 years ago, the seals returned to their origins but in much smaller numbers.
Adapted from materials provided by Durham University, via EurekAlert!, a service of AAAS.

A new way of estimating species richness.

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ScienceDaily (July 12, 2009) — Ask biologists how many species live in a pond, a grassland, a mountain range or on the entire planet, and the answers get increasingly vague. Hence the wide range of estimates for the planet's biodiversity, predicted to be between 2 million and 50 million species.

A new way of estimating species richness reported this month in the journal Ecology Letters by University of California, Berkeley, ecologist John Harte and colleagues, will make such estimates more precise for habitats of all sizes and types, from deserts to tropical rainforests.
"We know how to census the number of species in a square-meter plot or within an acre, but a major problem in conservation biology and ecology is estimating the diversity of biota at very large spatial scales, such as in the Amazon," said Harte, UC Berkeley professor of energy and resources. "This theory provides a much more accurate means of doing that."
The method, derived from the field of information theory, will affect not only conservation efforts to save species facing habitat loss, but also estimates of the impact of global warming, Harte said.
"Quantifying the magnitude of the extinction crisis involves estimating the richness of life in different habitats," he said. "The new theory is probably going to reduce the direness of the predictions of species loss under either habitat loss or climate change at the largest spatial scales, but it will increase (the direness) of estimates of loss at smaller scales."
Losing half of a small biome, for example, will have a worse impact than people think, while losing half of a large area would turn out better, he said.
Harte, who spends his summers in the Rocky Mountains studying the impact of climate change on plants, has for decades mulled over the problem of extrapolating from small study plots to large areas. Census takers have mastered this art, profiling the U.S. population by sampling small representative subsets. When biologists try to profile specific animals, plants or microbes of the Amazon, however, the estimates based on a small number of meter- or acre-size plots can vary by a factor of 10.
Ecological estimates of the number of species at large scales come from a hypothetical curve based on fractals, which predicts that the number of species will increase with area, but increase more slowly for larger and larger areas - a power-law rise with the number of species proportional to the ¼ power of the area.
"You can sample an area and count the number of species, and then double the area and find more species, but not twice as many, because the species overlap," Harte said.
He and colleague Jessica Green showed in 2003 that the theory of fractals, which posits that physical patterns such as the distribution of plants look similar on small and large scales, does not explain species richness over large areas. In addition, experimental tests of the species-area relationship showed that the curve has to be tweaked for every class of organisms and habitat studied.
Harte and colleagues Adam Smith of UC Berkeley and David Storch of Charles University in Prague, Czech Republic, decided to approach the problem from the perspective of information theory, which has provided key insights into thermodynamics and statistical mechanics.
In their report, they say that maximizing the information entropy - making full use of what is known from small plots without assuming anything about the unknown, larger areas - "provided a formal and robust derivation of the relationship between number of species and area."
The method not only scales up from measurements in small plots to provide more precise estimates of the number of species over large areas, but provides a universal species-area relationship, Harte emphasized.
"People have been finding different curves when looking at different organisms or in different habitats, but in fact, all these curves are the same," he said. "There really is a universal curve people are sampling, they are just sampling along different parts of the curve depending on the habitat or class of organisms."
Harte, Smith and Storch tested their theory with data from one of the few areas on Earth that has been thoroughly studied on both the small and large scale - the Western Ghats mountain range of India overlooking the Arabian Sea. A "biodiversity hotspot" of nearly 60,000 square kilometers, the Western Ghats are partially protected and have been studied extensively by Indian scientists in small sections - 48 quarter-hectare plots - and through large-scale surveys, Harte said.
While earlier species-area theories predict between 400 and 500 species of trees throughout the range of low hills, Harte's theory estimates around 1,070. To date, Indian scientists have documented more than 900 tree species in the preserve. Because a handful of new species is discovered each year, scientists guess that the Western Ghats contain between 1,000 and 1,100 species in all, Harte said.
"Before our publication, there really was no solidly-based theory that provided a means of making such estimates," he said.
The newly derived relationship between number of species and area is mathematically more complicated, but it does predict that as the area increases, the number of new species found approaches zero. This is more realistic than the previous species-area curve, which theoretically predicts an infinite number of species.
Harte has already received several dozen requests for reprints, and he predicts "it will generate a lot of discussion. I think the debate is going to be interesting."
The study was supported by the National Science Foundation, the Czech Ministry of Education and the Academy of Sciences of the Czech Republic, of which Storch is a member.
Adapted from materials provided by University of California - Berkeley.

Mystery Of Bat With An Extraordinary Nose Solved

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ScienceDaily (July 7, 2009) — A research paper co-written by a Virginia Tech faculty member explains a 60-year mystery behind a rare bat's nose that is unusually large for its species.

The article, "Acoustic effects accurately predict an extreme case of biological morphology," by Z. Zhang, R. Müller, and S.N. Truong, details the adult Bourret's horseshoe bat (known scientifically as the "Rhinolophus paradoxolophus," meaning paradoxical crest), and it's roughly 9 millimeters in length nose. The typical horseshoe bat's nose is half that long, said Rolf Mueller, an associate professor with the Virginia Tech mechanical engineering department and director for the Bio-inspired Technology (BIT) Laboratory in Danville, Va. "This nose is so much larger than anything else," among other bats of the region, he said.
Mueller's findings show that the bat uses its elongated nose to create a highly focused sonar beam. Bats detect their environment through ultrasonic beams, or sonar, emitted from their mouths -- or noses, as in the case of the paradoxolophus bat. The echoes of the sound wave convey a wealth of information on objects in the bat's environment. This bat from the remote rainforests of South East Asia received its name 58 years ago because of its mysterious trait.
Much like a flashlight with an adjuster that can create an intense but small beam of light, the bat's nose can create a small but intense sonar beam. Mueller and his team used computer animation to compare varying sizes of bat noses, from small noses on other bats to the large nose of the paradoxolophus bat. In what Mueller calls a perfect mark of evolution, he says his computer modeling shows the length of the paradoxolophus bat's nose stops at the exact point the sonar beam's focal point would become ineffective.
"By predicting the width of the ultrasonic beam for each of these nose lengths with a computational method, we found that the natural nose length has a special value: All shortened noses provided less focus of the ultrasonic beam, whereas artificially elongated noses provided only negligible additional benefits," Mueller said. "Hence, this unusual case of a biological shape can be predicted accurately from its physical function alone."
The findings with the paradoxolophus bat are part of a larger study of approximately 120 different bat species and how they use sonar to perceive their environment. Set to finish in February 2010, it is hoped the study's focus on wave-based sensing and communication in bats will help spur groundwork for innovations in cell phone and satellite communications, as well as naval surveillance technology.
Mueller worked on the study with engineers and scientists from China's Shandong University, where he held a professorship when the research project began, and the Vietnamese Academy of Sciences. The article will appear in Physical Review Letters' print edition on July 17 and on the Web site on July 14.
Adapted from materials provided by Virginia Tech, via EurekAlert!, a service of AAAS.

Mangrove-dependent Animals Globally Threatened

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ScienceDaily (July 7, 2009) — Substantial numbers of terrestrial vertebrates are restricted to mangrove forests. Many of these specialized species are listed as threatened by the International Union for the Conservation of Nature. Prospects for mangrove-restricted animals are bleak, because more than two percent of mangrove forests are lost each year.

More than 40 percent of a sample of amphibians, reptiles, mammals, and birds that are restricted to mangrove ecosystems are globally threatened with extinction, according to an assessment published in the July/August issue of BioScience. The study, by David A. Luther of the University of Maryland and Russell Greenberg of the Smithsonian Migratory Bird Center, was based on an extensive literature search and expert consultations.
The conclusions emphasize the vulnerability of animals that are dependent on a habitat rapidly being lost or degraded through coastal development, overexploitation, pollution, and changes in sea level and salinity.
Mangroves, which are salt-tolerant woody plants concentrated along coastal margins, generally in warm regions, have long been known to support many species of animals. Hundreds of vertebrates are sometimes found in mangroves, but Luther and Greenberg concentrated on the 69 terrestrial vertebrate species and subspecies that seem restricted to mangroves: 48 birds, 14 reptiles, 6 mammals, and 1 amphibian. These include several species with striking adaptations, such as specialized glands to excrete salt. The ground foragers among them feed primarily on crabs, but many of the birds feed on insects. For unclear reasons, mangrove-restricted species and subspecies are concentrated in Asia and Australia.
Between the early 1980s and 2001, between 19 and 35 percent of the world's mangrove forest area was lost. At this rate of loss--about 2 percent each year--mangroves could be extinct in 100 years. Only 27 of the terrestrial vertebrates that are dependent on mangroves have been assessed by the IUCN (International Union for the Conservation of Nature), and 13 of those are classified as threatened on the IUCN Red List, Luther and Greenberg report. They urge research aimed at predicting how continuing changes to mangrove forests are likely to affect the species found there: such information could guide attempts to conserve these specialized ecosystems.
Journal reference:
David A. Luther and Russell Greenberg. Mangroves: A Global Perspective on the Evolution and Conservation of Their Terrestrial Vertebrates. BioScience, July/August
Adapted from materials provided by American Institute of Biological Sciences, via EurekAlert!, a service of AAAS.

New Monkey Discovered In Brazil -- Threatened By Proposed Dams And Other Development In Region

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ScienceDaily (July 7, 2009) — The Wildlife Conservation Society (WCS) announced on July 7 the discovery of a new monkey in a remote region of the Amazon in Brazil.

The monkey is related to saddleback tamarins, which include several species of monkeys known for their distinctively marked backs. The newly described distinct subspecies was first seen by scientists on a 2007 expedition into the state of Amazonas in northwestern Brazil.
The discovery was published in the June online edition of the International Journal of Primatology. Authors of the study include Fabio Röhe of the Wildlife Conservation Society, José de Sousa e Silva Jr. of Museu Paraense Emílio Goeldi, Ricardo Sampaio of the Instituto Nacional de Parquisas de Amaozônia, and Anthony B. Rylands of Conservation International.
Researchers have dubbed the monkey Mura's saddleback tamarin (Saguinus fuscicollis mura) named after the Mura Indians, the ethnic group of Amerindians of the Purus and Madeira river basins where the monkey occurs. Historically this tribe was spread through the largest territory of any of the Amazonian Indigenous peoples, extending from the Peruvian frontier today (Rio Yavari) east to the Rio Trombetas.
The monkey is mostly gray and dark brown in color, with a distinctly mottled "saddle." It weighs 213 grams (less than ¾ of a pound) and is 240 millimeters (9 inches tall) with a 320 millimeter (12.6 inch) tail.
"The Wildlife Conservation Society is extremely proud to be part of this exciting discovery in the Amazon," said Dr. Avecita Chicchon, Director of WCS's Latin America Programs. "We hope that the discovery will draw attention to conservation in this very fragile but biodiverse region."
According to the study's authors, the monkey is threatened by several planned development projects in the region, particularly a major highway cutting through the Amazon that is currently being paved. Conservationists fear the highway could fuel wider deforestation in the Amazon over the next two decades. Other threats to the region include a proposed gas pipeline and two hydroelectric dams currently in the beginning stages of construction.
"This newly described monkey shows that even today there are still major wildlife discoveries to be made," said the study's lead author, Fabio Röhe of the Wildlife Conservation Society. "This discovery should serve as a wake-up call that there is still so much to learn from the world's wild places, yet humans continue to threaten these areas with destruction."
Journal reference:
Fabio Röhe, José de Sousa e Silva, Ricardo Sampaio and Anthony B. Rylands. A New Subspecies of Saguinus fuscicollis (Primates, Callitrichidae). International Journal of Primatology, 2009; DOI: 10.1007/s10764-009-9358-x
Adapted from materials provided by Wildlife Conservation Society, via EurekAlert!, a service of AAAS.

Battle Of The Sexes Benefits Offspring, Says Research In Birds

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ScienceDaily (July 6, 2009) — Parents compensate for a lazy partner by working harder to bring up their offspring, but not enough to completely make up for the lack of parenting, says research by bird biologists at the University of Bath.

In nature, it is quite rare for both parents to be involved in raising young, but it is very common in birds, some fish and primates including humans. Researchers therefore wanted to find out why, for some animals, parents stick together.
The study, published in the Journal of Evolutionary Biology, analysed more than 50 previous studies of birds to understand why and how they share their parental duties.
The research was led by Dr Freya Harrison and Professor Tamás Székely at the Biodiversity lab at the University of Bath, in collaboration with researchers from the University of Bristol and the University of Debrecen (Hungary).
Dr Harrison explained: “Caring for offspring is essential for their survival in many species, but it is also very costly in time and effort. Time spent bringing up your young means lost opportunities for remating and having more offspring, so parents face a trade-off between caring for current offspring and creating future offspring.
“This creates a conflict of interest between parents, since each parent would benefit by leaving their partner holding the baby whilst they go off and start a new brood elsewhere.
“This is exactly what happens in most animal species, so we wanted to understand how and why animals like birds and primates have evolved the tendency to share their parental duties.”
The researchers analysed data published over the last 30 years on parenting in birds to see if there was a common pattern in the behaviour of all the species studied.
Dr Harrison said: “In our study we found that if one parent starts slacking off or deserts, its mate works harder to bring up the brood, but not so hard as to completely compensate for their partner’s laziness.
“Some say that marriage is a state of antagonistic cooperation - in this case we found that the secret to a stable pairing was to only partially compensate for your lazy partner’s failings, to make sure that they stick around.”
Professor Innes Cuthill, Professor of Behavioural Ecology at the University of Bristol, added: “Of course, we are not claiming that fish and birds, or even humans, are necessarily making a consciously calculated decision.
“More likely there are innate rules for responding, perhaps modified through learning, that allow successful participation in joint activities without leaving room for being exploited.”
The researchers hope that this work could help scientists better understand how biparental care has evolved in humans.
The study was supported by the European Commission coordination action project: Integrating Cooperation Research Across Europe (INCORE).
Journal reference:
Harrison et al. How is sexual conflict over parental care resolved? A meta-analysis. Journal of Evolutionary Biology, 2009; DOI: 10.1111/j.1420-9101.2009.01792.x
Adapted from materials provided by University of Bath.

Once-a-month Pill For Both Fleas And Ticks In Dogs And Cats

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ScienceDaily (July 6, 2009) — Scientists in New Jersey are describing discovery and successful tests of the first once-a-month pill for controlling both fleas and ticks in domestic dogs and cats.

Peter Meinke and colleagues at Merck Research Laboratories note the need for better ways of controlling fleas and ticks, driven in part by increases in pet ownership. Estimates suggest that there were 71 million pet dogs and 81 million pet cats in the United States alone in 2007 — up from 61 million and 70 million in 2001.
Although many powders, sprays and other topical agents are on the market, many pet owners prefer the convenience of pills. Products given orally can reach more parts of an animal's body, do not wash off in rain or bath water, and don't transfer from pets to people. At least one existing pill fights fleas in pets, but does not appear effective for ticks.
In tests on fleas and ticks in dogs and cats, a single dose of the new pill was 100 percent effective in protecting against both fleas and ticks for a month. There were no signs of toxic effects on the animals. Scientists obtained the flea and tick fighter from a substance first found in a fungus that "has the potential to usher in a new era in the treatment of ecoparasitic [ticks and fleas, for instance] infestations in companion animals."
Journal reference:
Meinke et al. Discovery of the Development Candidate N-tert-Butyl Nodulisporamide: A Safe and Efficacious Once Monthly Oral Agent for the Control of Fleas and Ticks on Companion Animals. Journal of Medicinal Chemistry, 2009; 52 (11): 3505 DOI: 10.1021/jm801334v
Adapted from materials provided by American Chemical Society.

World's First 'Self-Watering' Plant: Desert Rhubarb

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ScienceDaily (July 5, 2009) — Researchers from the Department of Science Education-Biology at the University of Haifa-Oranim have managed to make out the "self-irrigating" mechanism of the desert rhubarb, which enables it to harvest 16 times the amount of water than otherwise expected for a plant in this region based on the quantities of rain in the desert. This is the first example of a self-irrigating plant worldwide.

The desert rhubarb grows in the mountains of Israel's Negev desert, where average precipitation is particularly low (75 mm per year). Unlike most of the other desert plant species, which have small leaves so as to minimize moisture loss, this plant is unique in that its leaves are particularly large; each plant's rosette of one to four leaves reaches a total diameter of up to one meter. Prof. Simcha Lev-Yadun, Prof. Gidi Ne'eman and Prof. Gadi Katzir came across this unique plant growing in the desert while studying the field area with students of the Department of Science Education-Biology of the University of Haifa-Oranim, and noticed that its leaves are unusually large and covered with a waxy cuticle. They observed an exceptionally ridged structure on each leaf, forming a leaf structure that resembles the habitat's mountainous topography.
The scientists explained that these deep and wide depressions in the leaves create a "channeling" mountain-like system by which the rain water is channeled toward the ground surrounding the plant's deep root. Other desert plants simply suffice with the rain water that penetrates the ground in its immediate surroundings.
The findings have shown that the natural selection process has resulted in the evolution of this plant's extremely large leaves, which improved its ability to survive in the arid climate of the desert.
The results of experiments and analysis of the plant's growth - in an area with an average annual rainfall of 75 mm - showed that the desert rhubarb is able to harvest quantities of water that are closer to that of Mediterranean plants, reaching up to 426 mm per year. This is 16 times the amount of water harvested by the small-leafed plants of the Negev desert region. When the research team watered the plant artificially, they observed how the water flows along the course of the leave's depressed veins to the ground surrounding the plant's single root and then penetrates the ground to a depth of 10 cm or more. Under the experimental conditions, water penetrated the ground only as deep as 1 cm.
"We know of no other plant in the deserts of the world that functions in this manner," the researchers concluded.
Adapted from materials provided by University of Haifa.

Climate Change And The Mystery Of The Shrinking Sheep

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ScienceDaily (July 4, 2009) — Milder winters are causing Scotland's wild breed of Soay sheep to get smaller, despite the evolutionary benefits of possessing a large body, according to new research.

The new study provides evidence for climate change as the cause of the mysterious decrease in the size of wild sheep on the Scottish island of Hirta, first reported by scientists in 2007. The researchers believe that, due to climate change, survival conditions on Hirta are becoming less challenging, which means slower-growing, smaller sheep are more likely to survive the winters than they once were. This, together with newly-discovered so-called 'young mum effect' whereby young ewes produce smaller offspring, explains why the average size of sheep on the island is decreasing.
Classical evolutionary theory suggests that over time the average size of wild sheep increases, because larger animals tend to be more likely to survive and reproduce than smaller ones, and offspring tend to resemble their parents. However, among the Soay sheep of Hirta, a remote Scottish island in the St Kilda archipelago, average body size has decreased by approximately 5% over the last 24 years.
The research team analysed body size and life history data, which records the timing of key milestones throughout an individual sheep's life, for Soays on Hirta over this 24 year period. They found that sheep on the island are not growing as quickly as they once did, and that smaller sheep are more likely to survive into adulthood. This is bringing down the average size of sheep in the population over all.
Professor Coulson suggests that this is because shorter, milder winters, caused by global climate change, mean that lambs do not need to put on as much as weight in the first months of life to survive to their first birthday as they did when winters were colder.
He explains: "In the past, only the big, healthy sheep and large lambs that had piled on weight in their first summer could survive the harsh winters on Hirta. But now, due to climate change, grass for food is available for more months of the year, and survival conditions are not so challenging - even the slower growing sheep have a chance of making it, and this means smaller individuals are becoming increasingly prevalent in the population."
Their results suggest that the decrease in average body size seen in Hirta's sheep is primarily an ecological response to environmental changes over the last 25 years; evolutionary change has contributed relatively little.
In addition, the research team also discovered that the age at which a female sheep gives birth affects the size of her offspring. They realised that young Soay ewes are physically unable to produce offspring that are as big as they themselves were at birth. This 'young-mum' effect had not been incorporated into previous analyses of natural selection, which explains in part why the sheep of Hirta are defying biologists' expectations.
"The young mum effect explains why Soay sheep have not been getting bigger, as we expected them to," concludes Professor Coulson, "But it is not enough to explain why they're shrinking. We believe that this is down to climate change. These two factors are combining to override what we would expect through natural selection."
The research was carried out in collaboration with scientists from the Universities of Leeds, Cambridge, Edinburgh and Stanford. It was funded in the UK by the Natural Environment Research Council (NERC).
Journal reference:
Arpat Ozgul et al. The Dynamics of Phenotypic Change and the Shrinking Sheep of St. Kilda. Science, July 3, 2009
Adapted from materials provided by Imperial College London, via EurekAlert!, a service of AAAS.

Small Heat-Shielded Habitats Could Help Threatened Species Survive Climate Change

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ScienceDaily (July 3, 2009) — Intelligent countryside management could improve the survival chances of animal and plant species threatened by climate change. The creation of small heat-shielded habitats and better links between habitats would counteract a moderate temperature increase and give threatened species more time to adapt better and/or to migrate to cooler regions.

This is the conclusion drawn by scientists at the Helmholtz Centre for Environmental Research (UFZ) from a British study on saving the Large Blue butterfly (Maculinea arion). This butterfly became extinct in Britain in 1979 and was reintroduced there 25 years ago. Since then, the butterfly's reintroduction is seen as a model for the conservation of endangered insects.
A form of countryside management that creates cooler microclimatic conditions, for example through taller grass in today's meadows, should mitigate the effects of global warming in the short and medium term, say the researchers, writing in the current issue of Science. This is, however, not a long-term solution – just a stop-gap for the next few decades.
The Large Blue butterfly (Maculinea arion) is rather rare throughout many European countries. It is found in meadows and pastures where thyme grows because the caterpillars eat only this plant or its close relative, wild marjoram (Origanum vulgare). The butterfly's survival depends on a large number of factors - as it belongs to the genus Maculinea. This means that it is dependent not only on a specific food plant for the caterpillars, but also on a particular species of ant. The caterpillars trick the ants into carrying them into their nest where they feed on the ants' brood through the winter.
However, this trick works only on one very specific type of ant – only Myrmica sabuleti is tricked by the scent of the caterpillars' of the Large Blue. Other ants see through the disguise and remove any caterpillars that have been carried into their nest. During the decline of the Large Blue in Britain, M. sabuleti ants were crowded out by a competing species of ant, M. scabrinoides, which copes better with lower soil temperatures. "A change in the height of the grass by one or two centimetres can result in a two or three degree temperature change in the ants' brood chambers just below the surface," explains Prof. Jeremy A. Thomas of Oxford University. The biologist spent decades studying the complicated interplay and his findings have now been published in the same issue of Science - in a publication to which the Helmholtz scientists refer.
The soil temperature dropped because the meadows on which the butterflies and ants had lived together for so long were grazed less, and because an epidemic among the wild rabbits, which used to keep the grass short, caused their numbers to plummet. A change in land use had thrown the sensitive interplay between the species off balance. By the time this was realised, it was already too late for the Large Blue in Britain. Once the precise reasons for the disappearance of the butterfly populations became known, scientists kept a lookout for suitable donor populations in other European countries so that the butterfly could be reintroduced. Eventually, butterflies were brought in from Sweden and the meadows were kept short in line with the scientific findings.
It was this that turned the reintroduction of the Large Blue into a success story. There are now more butterflies of this highly endangered species living in the UK than there were when records began in the 1950s. "The fact that it was possible to stop and reverse the decline could make this a model for many other insect conservation projects," hopes Jeremy Thomas.
His fellow scientists from the UFZ go a step further in a second article published in Science. The problem with the Large Blue butterfly was that the longer grass made the soil cooler. However, climate change will pose the opposite problem, and many species could simply find it too hot. "We could counter this by simply letting the grass grow longer. Then the microclimate at soil level would remain constant," suggests Dr Josef Settele of the UFZ, one of the two authors of the article. "This may sound trivial, but it is a very simple example of how modified countryside management can cushion against climate changes to give many species a breathing space to adapt or to migrate." Settele coordinates a number of large research projects investigating risks to biodiversity.
In order to recognise environmental changes like these in good time, researchers are now relying on more intensive environmental monitoring. This includes a butterfly monitoring programme in which thousands of volunteers in countries like the UK, the Netherlands and Germany count and record butterflies using the same method. The Europe-wide butterfly-monitoring programme is being coordinated by Butterfly Conservation Europe. In Germany the Helmholtz Centre for Environmental Research (UFZ) has taken on the coordination of the German butterfly-monitoring programme (Tagfalter-Monitoring Deutschland, TMD). "Systematic records, like the ones kept for the Large Blue in England, show the potential offered by data that has been recorded systematically over the long term.
The first four years of the German butterfly-monitoring programme have been very successful. The active participation of around 600 volunteers makes us optimistic that we will be able to make many more statements about a large number of species and large areas in a few years' time," says Elisabeth Kühn, co-author of the UFZ's contribution to Science. In the long term, the TMD data will form an important basis for realistic modelling, e.g. to show the impacts of climate and land use change on butterfly communities. This will provide an opportunity to make forecasts.
The Large Blue butterfly has been included in the European Grassland Butterfly Indicator, which provides information about the ecological status of meadows and pastures by recording typical butterflies. If monitoring can be firmly established as an early-warning system in the long term, there will be a greater chance of preventing species and populations from disappearing entirely, following the British example – ideally before they die out and have to be reintroduced. The UFZ authors therefore highlight the significance of the British study for insect conservation in general: many specialist species, which are frequently endangered, can be conserved only with the help of good ecological data and countryside management which has been derived from it – usually at landscape level.
Journal references:
Josef Settele and Elisabeth Kühn. Insect Conservation. Science, 325, 41-42.
Thomas et al. Successful Conservation of a Threatened Maculinea Butterfly. Science, 2009; 325 (5936): 80 DOI: 10.1126/science.1175726
Dover et al. The influences of landscape structure on butterfly distribution and movement: a review. Journal of Insect Conservation, 2009; 13 (1): 3 DOI: 10.1007/s10841-008-9135-8
Adapted from materials provided by Helmholtz Association of German Research Centres, via EurekAlert!, a service of AAAS.

Salamanders, Regenerative Wonders, Heal Like Mammals, People

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ScienceDaily (July 2, 2009) — The salamander is a superhero of regeneration, able to replace lost limbs, damaged lungs, sliced spinal cord -- even bits of lopped-off brain.

But it turns out that remarkable ability isn't so mysterious after all -- suggesting that researchers could learn how to replicate it in people.
Scientists had long credited the diminutive amphibious creature's outsized capabilities to "pluripotent" cells that, like human embryonic stem cells, have the uncanny ability to morph into whatever appendage, organ or tissue happens to be needed or due for a replacement.
But in a paper set to appear July 2 in the journal Nature, a team of seven researchers, including a University of Florida zoologist, debunks that notion. Based on experiments on genetically modified axolotl salamanders, the researchers show that cells from the salamander's different tissues retain the "memory" of those tissues when they regenerate, contributing with few exceptions only to the same type of tissue from whence they came.
Standard mammal stem cells operate the same way, albeit with far less dramatic results -- they can heal wounds or knit bone together, but not regenerate a limb or rebuild a spinal cord. What's exciting about the new findings is they suggest that harnessing the salamander's regenerative wonders is at least within the realm of possibility for human medical science.
"I think it's more mammal-like than was ever expected," said Malcolm Maden, a professor of biology, member of the UF Genetics Institute, and author of the paper. "It gives you more hope for being able to someday regenerate individual tissues in people."
Also, the salamanders heal perfectly, without any scars whatsoever, another ability people would like to learn how to mimic, Maden said.
Axolotl salamanders, originally native to only one lake in central Mexico, are evolutionary oddities that become sexually reproducing adults while still in their larval stage. They are useful scientific models for studying regeneration because, unlike other salamanders, they can be bred in captivity and have large embryos that are easy to work on.
When an axolotl loses, for example, a leg, a small bump forms over the injury called a blastema. It takes only about three weeks for this blastema to transform into a new, fully functioning replacement leg -- not long considering the animals can live 12 or more years.
The cells within the blastema appear embryonic-like and originate from all tissues around the injury, including the cartilage, skin and muscle. As a result, scientists had long believed these cells were pluripotential -- meaning they came from a variety of sites and could make a variety of things once functioning in their regenerative mode.
Maden and his colleagues at two German institutions tested that assumption using a tool from the transgenic kit: the GFP protein. When produced by genetically modified cells, GFP proteins have the useful quality of glowing livid green under ultraviolet light. This allows researchers to follow the origin, movement and destination of the genetically modified cells.
The researchers experimented on both adult and embryonic salamanders.
With the embryos, the scientists grafted transgenic tissue onto sites already known to develop into certain body parts, then observed how and where the cells organized themselves as the embryo developed. This approach allowed them to see, literally, what tissues the transgenic tissue made. In perhaps the most vivid result, the researchers grafted GFP-modified nerve cells onto the part of the embryo known to develop into the nervous system. Once the creatures developed, ultraviolet light exams of the adults revealed the GFP cells stretched only along nerve pathways -- like glowing green strings throughout the body
With the adults, they took tissue from specific parts or organs from transgenic GFP-producing axolotls, grafted it onto normal axolotls, then cut away a chunk of the grafted tissue to allow regeneration. They could then determine the fate of the grafted green cells in the emerging blastema and replacement tissue.
The researchers' main conclusion: Only 'old' muscle cells make 'new' muscle cells, only old skin cells make new skin cells, only old nerve cells make new nerve cells, and so on. The only hint that the axolotl cells could revamp their function came with skin and cartilage cells, which in some circumstances seemed to swap roles, Maden said.
Maden said the findings will help researchers zero in on why salamander cells are capable of such remarkable regeneration. "If you can understand how they regenerate, then you ought to be able to understand why mammals don't regenerate," he said.
Maden said UF researchers will soon begin raising and experimenting on transgenic axolotls at UF as part of the The Regeneration Project, an effort to treat human brain and other diseases by examining regeneration in salamanders, newts, starfish and flatworms.
Journal reference:
Martin Kragl et al. Cells keep a memory of their tissue origin during axolotl limb regeneration. Nature, July 2, 2009 DOI: 10.1038/nature08152
Adapted from materials provided by University of Florida, via EurekAlert!, a service of AAAS.

Keeping Fish in Home Aquariums: Two Is Not Company, As Far As Fish Are Concerned

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ScienceDaily (July 2, 2009) — It might be assumed that aquarium fish don't mind who or what they encounter in their tanks from one minute to the next, if their famously (but incorrectly) short memory is to be believed. Scientists at the Universities of Plymouth and Exeter have carried out research to show this is not the case and are striving to improve conditions for keeping fish in home aquaria.

In line with the aim to establish welfare guidelines for fish, these researchers have been collaborating with the WALTHAM Centre for Pet Nutrition, examining healthy stocking densities and the use of novel objects with fish commonly kept in home aquaria. This current research, to be presented on the 29th of June 2009 at the Society for Experimental Biology Meeting in Glasgow, looked at two common aquaria species, neon tetras and white cloud mountain minnows.
As Dr Katherine Sloman from the University of Plymouth explains 'fish kept alone or in pairs show higher levels of aggression than those kept in groups of ten or more; large groups are also more likely to exhibit natural behaviours such as shoaling'.
Further research is needed to ascertain the criteria for fish welfare in home aquaria; the results of these studies, funded by the WALTHAM Centre for Pet Nutrition, should go some way to improving welfare for these environmentally, economically and socially important and interesting animals.
Adapted from materials provided by Society for Experimental Biology, via EurekAlert!, a service of AAAS.