King penguins find their way easily in the dark polar winter, say scientists. A team, led by Anna Nesterova from the National Centre for Scientific Research in France, found that penguins could move through a colony in total darkness and that they were "strongly motivated" to find their partners.
Some Aboriginal people have traditionally defined one of their seasons by the emergence of this common butterfly. (Paul Sunnucks)
Australian scientists say they have uncovered a "causal link" between the early emergence of a common butterfly and human-induced global warming.
Dr Michael Kearney of the University of Melbourne and his colleagues report their study on the butterfly heteronympha merope in this week's issue of Royal Society journal Biology Letters.
"It's now coming out about 10 days earlier than it was 60 years ago," Dr Kearney said.
"When you look at the air temperatures over that time, it's getting warmer."
Dr Kearney says the local Wurundjeri Aboriginal people have traditionally defined one of their seasons as beginning when they see the male of the common brown butterfly on the wing.
"That part of their calendar would be shifted 10 days earlier," he says.
Dr Kearney says that while previous studies have found a correlation between global warming and animals coming out earlier in spring, this study is the first to provide evidence of a causal link between this phenomenon and human-induced global warming.
He says his team has carried out laboratory experiments to quantify the physiological effect of rising temperatures on butterflies and has also shown the measured temperature increases are not due to natural climatic variation.
"It's causal all the way through," he said.
For the laboratory work, team member Natalie Briscoe spent hours in the lab, feeding caterpillars under different conditions to see how temperature affected their emergence into winged butterflies.
"The warmer it is, the faster they will emerge," Dr Kearney said.
This enabled the researchers to calculate how many days it would take a caterpillar to emerge given a particular temperature.
They then combined this laboratory evidence on butterfly physiology with historical temperature records, to predict how soon butterflies would have emerged each year between 1944 and 2005.
Dr Kearney and the team found these predictions matched butterfly emergence times as stated in museum records.
Records showed an increase of approximately 0.14 degrees Celsius per decade in the region and the shift in emergence date had shifted 1.6 days per decade over the same period, he said.
The final step taken by the researchers was to link the regional temperature changes with human-induced global warming.
Team member and climatologist Professor David Karoly applied global circulation models to the Melbourne region, taking into account local factors that influenced climate.
This suggested that the regional temperature changes observed over the decade were unlikely to be observed without the influence of human greenhouse emissions, Dr Kearney said.
He and the team used temperature records from the Laverton weather station, located on Melbourne's outer edge.
This weather station was used to avoid the "urban heat island" effect of the city of Melbourne on temperature records.
The research is part of an Australian Research Council-funded project to predict the response of species to shifts in climate.
Dr Kearney says the team hopes the findings from the butterfly study can be applied to other, less common, species.
Could Smell Play a Role in the Origin of New Bird Species?
ScienceDaily (Mar. 24, 2010) — Two recently diverged populations of a southern California songbird produce unique odors, suggesting smell could contribute to the reproductive isolation that accompanies the origin of new bird species. The Indiana University Bloomington study of organic compounds present in the preen oils of Dark-eyed Juncos is described in this month's Behavioral Ecology.
"There's so much we don't know about the role of smell in bird behavior," said biologist Danielle Whittaker, the study's lead author. "Differences in smell could be affecting sexual behavior, parental care and even contribute to speciation."
Whittaker is a postdoctoral researcher in IU Bloomington biologist Ellen Ketterson's research group.
Led by Whittaker, a team of IU Bloomington biologists and chemists examined the chemical composition of preen oil, which is a compound birds secrete and spread around their bodies to straighten, protect and waterproof their feathers. To analyze the odor chemistry of preen oil, the scientists isolated 19 volatile molecules that can achieve a gaseous, more sniff-friendly state. The chemical isolation and analysis portion of the interdisciplinary project was led by IU Bloomington Department of Chemistry Distinguished Professor Milos Novotny and Senior Scientist Helena Soini.
The scientists found that each junco possesses a unique and recognizable odor profile that was stable over a two-week period and that could be used to distinguish it from other individuals. The odor profiles of male birds differed from those of female birds, and birds' odor profiles differed depending on which population they were from.
"This is the most comprehensive study of its kind," Whittaker said. "And as far as we know, it is the first time anyone has looked closely at these chemical compounds at the population level in any bird."
Last year, Whittaker, Ketterson, and others reported in the Journal of Avian Biology that juncos can use preen oils to distinguish members of their own species from other species, and between individuals of their own species. The present Behavioral Ecology study went a step further to see whether the chemical composition of preen oil varies among individuals, sexes and populations -- which might be meaningful in an evolutionary context.
The team collected juvenile juncos from two populations, one that resides in and around the University of California San Diego campus in La Jolla, Calif., and another that lives in the Laguna Mountains, about 42 miles east. After capture, the birds were transported to aviaries in Bloomington, Ind., and raised under identical environmental conditions. The scientists used gas chromatography-mass spectrometry to isolate 19 volatile compounds from the preen oils which are secreted from the birds' uropygial glands near the base of the tail.
The researchers confirmed that individual birds sampled over time produce levels of each of the volatile compounds that remain more or less constant. They also found gross differences between males and females, and between juncos from the UC San Diego population and birds from the mountains. These population differences were found even though the birds were raised in identical conditions, suggesting that the odors have a genetic, rather than an environmental or developmental basis.
The particular suite of 19 compounds is, as far as the scientists know, unique to juncos. However, this area of research is so new that odor chemistry profiles have been documented for only a few species. This field of research is growing rapidly as biologists realize the potential importance of scent in bird communication and evolution.
Until just a few years ago, most bird biologists believed that smell played little or no role in bird behavior. The olfactory bulb -- a portion of vertebrate brain known to interpret odors -- is small relative to birds' brain sizes. Birds also lack the vomeronasal organ that many mammals (and reptiles) use to sense pheromones specifically.
Then came the discovery that sea-faring petrels can smell so well that they can identify other birds through sense of smell alone. This discovery kicked off a re-examination of several bird species, and preliminary results suggest smell in birds is a behavioral cue that has been overlooked for far too long.
"We still don't know how common it is for birds to use smell," Whittaker said. "The evidence so far suggests there is much for us to learn."
Also contributing to the report were biology graduate student Jonathan Atwell, IU Bloomington chemistry graduate student Craig Hollars. Milos Novotny, Soini, and Hollars are members of the Institute for Pheromone Research, which Novotny directs. Ketterson, Novotny and Soini are also members of IU's Center for the Integrative Study of Animal Behavior.
The project was funded by grants from the National Science Foundation, the National Institutes of Health, and the IU Faculty Research Support Program, with additional support from the Indiana METACyt Initiative and funds from the Lilly Chemistry Alumni Chair.
1. D. J. Whittaker, H. A. Soini, J. W. Atwell, C. Hollars, M. V. Novotny, E. D. Ketterson. Songbird chemosignals: volatile compounds in preen gland secretions vary among individuals, sexes, and populations. Behavioral Ecology, 2010; DOI: 10.1093/beheco/arq033
Bird bones have evolved special features to make them stiffer and stronger than mammal bones, including high bone density, fusion of some bones and altered shape. Studies show that the main bone in the bird wing, the humerus, is quite round in cross-section, making it stronger and more resistant than a flat-sided bone would be to twisting forces encountered in flying. (Credit: Betsy Dumont, UMass Amherst)
ScienceDaily (Mar. 23, 2010) — For centuries biologists have known that bird bones are hollow, and even elementary school children know that bird skeletons are lightweight to offset the high energy cost of flying. Nevertheless, many people are surprised to learn that bird skeletons do not actually weigh any less than the skeletons of similarly sized mammals. In other words, the skeleton of a two-ounce songbird weighs just as much as the skeleton of a two-ounce rodent.
Bird biologists have known this for a long time, but it took a modern bat researcher, Elizabeth Dumont of the University of Massachusetts Amherst, to explain how bird skeletons can look so delicate and still be heavy. The answer is that bird bones are denser than mammal bones, which makes them heavy even though they are thin and sometimes even hollow.
Her findings, supported by bone density measurements, are published in the March 17 issue of Proceedings of the Royal Society B. As Dumont explains, "The fact that bird bones are denser than bones in mammals not only makes them heavier for their size, but it may also make them stiffer and stronger. This is a new way to think about how bird skeletons are specialized for flying and solves the riddle of why bird skeletons appear so lightweight and are still relatively heavy. This has never been explained fully and so has never gotten into the textbooks. I'd like to see that change."
Dumont measured the density of the cranium, the upper arm bone or humerus and the thigh or femur bones in song birds, rodents and bats by measuring bone mass and volume. "I found that, on average, these bones are densest in birds, followed closely by bats. Many other studies have shown that as bone density increases, so do bone stiffness and strength. Maximizing stiffness and strength relative to weight are optimization strategies that are used in the design of strong and stiff but lightweight man-made airframes," she points out. Density is a measure of mass per unit of volume; dense bones are both heavier and stronger, much as a titanium toothpick would be stronger than a wooden one.
Over time bird bones have evolved specializations that maximize stiffness and strength, Dumont says. These specializations include high bone density, a reduction in the total number of bones, fusion of some bones, and changes in bone shape. For example, a long history of studies have shown that the main bone in the bird wing, the humerus, is quite round in cross-section. This makes it stiffer in the same way that a round toothpick is harder to snap than a flat one.
Galileo described bird bones as lightweight in 1683, Dumont says. Her new data help to dispel the common misconception that bird skeletons are lightweight relative to body mass. Instead, bird and bat skeletons only appear to be slender and delicate -- because they are dense, they are also heavy. Being dense, strong and stiff is one more way that birds' and bats' bones are specialized for flight.
1. Elizabeth R. Dumont. Bone density and the lightweight skeletons of birds. Proceedings of The Royal Society B Biological Sciences, 2010; DOI: 10.1098/rspb.2010.0117
How Bats Avoid Collisions: Making Mental Templates of Sound and Echo
A Brown University-led team strapped microphones onto heads of big brown bats and recorded the sounds they emitted and the echoes that returned to learn how bats detect objects in space and successfully maneuver around them. (Credit: James Simmons Lab, Brown University)
ScienceDaily (Mar. 29, 2010) — For years, Brown University neuroscientist James Simmons has filmed bats as they flew in packs or individually chased prey in thick foliage. All the while, he asked himself why the bats never collided with objects in their paths or with each other.
"You wonder, how do they do it?" he said.
After a series of innovative experiments designed to mimic a thick forest, Simmons and colleagues at Brown and in Japan have discovered how bats are so adept at avoiding objects, real or perceived. In a paper published in the Proceedings of the National Academy of Sciences early edition, the scientists report that echolocating bats minimize sound wave interference by tweaking the frequencies of the sounds they emit -- their broadcasts -- to detect and maneuver around obstacles. The scientists also found that bats make mental templates of each broadcast and the echo it creates, to differentiate one broadcast/echo set from another.
The research is important, because it may lead to the design of better sonar and radar systems by capitalizing on the bats' natural ability to ferret out duplicative echoes in environments that otherwise could produce "phantom" objects.
The group created a 13-row long by 11-row wide U-shaped grid of ceiling-to-floor chain links to test big brown bats' ability to locate obstacles at various distances in their flight path and to make nearly instantaneous adjustments. The researchers ussed a miniature radio microphone created by the Japanese authors and attached it to the bats' heads to record their sounds (which are made in pairs). Other microphones placed in the room recorded the echoes produced from the bats' broadcasts, giving the researchers a comprehensive, accurate recording of the bats' echo-processing methods. The scientists also filmed the bats with high-resolution video cameras.
The team noticed almost immediately that the bats were confronted with overlapping echoes to their rapid firing of broadcasts. That could create confusion where obstacles were located and even produce objects that weren't really there.
"When there are a lot of obstacles in the environment, a bat needs to emit sounds quickly," said Mary Bates, a fourth-year graduate student at Brown and a contributing author on the paper. "It can't wait for another sound to return before updating its image" (of the scene in which it's flying).
An echo from the bat's first broadcast could masquerade as the echo from a subsequent broadcast. The bat overcomes this potentially confusing cascade of signals by making a template, or mental fingerprint, of each broadcast and corresponding echo, the team learned. That way, the bat needs only to slightly alter the frequency of its broadcast to create a broadcast/echo template that doesn't match the original. The team found that bats change the frequency of their broadcasts by no more than 6 kilohertz. That's a good thing, as bats' frequency range covers only roughly 20 to 100 kilohertz.
"They've evolved this, so they can fly in clutter," said Simmons, professor of neuroscience. "Otherwise, they'd bump into trees and branches."
Shizuko Hiryu and Hiroshi Riquimaroux from Doshisha University in Japan are contributing authors on the paper. The research was funded by the National Institutes of Health, the National Science Foundation, the Office of Naval Research, Rhode Island Space Grant, the Japan Society for the Promotion of Science, the Japanese Ministry of Education, Culture, Sports, Science and Technology, the Special Research Grants for the Development of Characteristic Education from the Promotion and Mutual Aid Corporation for Private Schools of Japan and the Innovative Cluster Creation Project.
1. Shizuko Hiryu, Mary E. Bates, James A. Simmons, and Hiroshi Riquimaroux. FM echolocating bats shift frequencies to avoid broadcast-echo ambiguity in clutter. Proceedings of the National Academy of Sciences, March 29, 2010 DOI: 10.1073/pnas.1000429107
Two crayfish fight in a cloud of visualized urine. (Credit: Fiona Berry)
ScienceDaily (Mar. 30, 2010) — Walking through urine drives crayfish into an aggressive sexual frenzy. Researchers writing in the open access journal BMC Biology suggest that a urine-mediated combination of aggressive and reproductive behaviour ensures that only the strongest males get to mate.
Fiona Berry and Thomas Breithaupt from the University of Hull, UK, investigated the effects of urine-based chemical signaling on sexually active crayfish. Breithaupt said, "Our results confirm that females initiate courtship behavior; males will only attempt to mate if they receive urinary signals from the female. Females, however, send a mixed message by releasing an aphrodisiac while also acting very aggressively towards the males."
Females could profit in different ways from displaying such conflicting signals. By stimulating aggressive behaviour in males, females can gauge male size and strength and thereby ensure that only the fittest males get to fertilise their eggs.
According to the researchers, "Timing seems to be key to this interaction as urine induces aggression in both sexes. Males will discontinue urine release early in the sexual encounter, which may mitigate the female's antagonism and enhance mating success."
1. Fiona C Berry and Thomas Breithaupt. To signal or not to signal? Chemical communication by urine-borne signals mirrors sexual conflict in crayfish. BMC Biology, (in press)
Two hyenas "giggle" over an antelope spine. (Credit: Theunissen et al., BMC Ecology)
ScienceDaily (Mar. 30, 2010) — Acoustic analysis of the 'giggle' sound made by spotted hyenas has revealed that the animals' laughter encodes information about age, dominance and identity. Researchers writing in the open access journal BMC Ecology recorded the calls of 26 hyenas in captivity and found that variations in the giggles' pitch and timbre may help hyenas to establish social hierarchies.
Frédéric Theunissen, from the University of California at Berkeley, USA, and Nicolas Mathevon, from the Université Jean Monnet, St. Etienne, France worked with a team of researchers to study the animals in a field station at Berkeley. Theunissen said, "The hyena's laugh gives receivers cues to assess the social rank of the emitting individual. This may allow hyenas to establish feeding rights and organize their food-gathering activities."
The researchers found that while the pitch of the giggle reveals a hyena's age, variations in the frequency of notes can encode information about dominant and subordinate status. These vocalizations are mainly produced during food contests by animals that are prevented from securing access to a kill, and have been considered a gesture of submission.
Theunissen and colleagues also suggest that the giggle may be a sign of frustration and that it may be intended to summon help. He said, "Lions often eat prey previously killed by hyenas. A solitary hyena has no chance when confronted by a lion, whereas a hyena group often can 'mob' one or two lions and get their food back. Giggles could therefore allow the recruitment of allies. Cooperation and competition are everyday components of a hyena's life. When hearing a giggling individual, clan-mate hyenas could receive information about who is getting frustrated (in terms of individual identity, age, status) and decide to join the giggler, or conversely to ignore it or move away."
The researchers plan to further test these hypotheses with playback experiments in the field.
1. Nicolas Mathevon, Aron Koralek, Mary Weldele, Steve E Glickman and Frederic E Theunissen. What the hyena's laugh tells: Sex, age, dominance and individual signature in the giggling call of Crocuta crocuta. BMC Ecology, 2010; (in press)
ScienceDaily (Apr. 8, 2010) — The vivid colors and designs animals use to interact with their environments have awed and inspired since before people learned to draw on the cave wall.
But how different creatures in the animal kingdom -- from colorful birds and reef fish to butterflies and snakes -- make and deploy their artful designs is one of nature's deepest secrets. Now, however, a team of researchers from the Howard Hughes Medical Institute at the University of Wisconsin-Madison has exposed the fine details of how animals make new body ornamentation from scratch. The work, the result of years-long and laborious experimentation, is published April 7 in the journal Nature.
"How do you generate complex patterns? This is a question that has interested biologists for a really long time," says Sean Carroll, a UW-Madison molecular biologist and the senior author of the Nature report. "In this case, we at first had no clue. But now we think we've figured out all the key ingredients and we believe they are generally applicable (to many animals)."
The new study is important because it is the first to provide concrete evidence for a long-hypothesized system for generating animal color patterns, be they stripes, spots or any of the myriad designs animals use to camouflage themselves or find a mate. In particular, the Wisconsin group is the first to identify a color-inducing morphogen, a diffusible protein that tells certain cells to make pigment.
To ferret out the secret of animal ornamentation, Carroll and his UW-Madison colleagues, Thomas Werner and Shigeyuki Koshikawa, and Thomas Williams, now at the University of Dayton, pried loose the molecular details and evolutionary history of how a species of North American fruit fly, Drosophila guttifera, generates a complex pattern of 16 wing spots.
The group discovered a morphogen, a protein present in embryonic tissue and encoded by a gene known as Wingless, which seems to be a linchpin of wing decoration. Late in wing development, the Wingless morphogen is produced and diffuses through tissue where it prompts cells in certain areas of the wing to make pigment. "It acts by triggering responding cells to do things, in this case make color," Carroll explains.
In Drosophila guttifera, the morphogen acts in proximity to existing physical landmarks such as the intersections of veins and cross veins on the wing. The positioning of the spots, in short, is dictated by these pre-existing patterns, notes Carroll: "The Wingless molecule is deployed in this species at specific points in time and in specific places -- the places where the spots are going to be."
The role of the Wingless morphogen was detailed by the painstaking genetic manipulation of flies that took three years and the injection of nearly 20,000 fly embryos to accomplish. Complicating the project is the fact that Drosophila guttifera is little used in research and its genome has not been sequenced.
However, by inserting the Wingless gene into different parts of the fly's genome, the team was able to successfully manipulate the decoration of the fly's wing, creating stripes instead of spots, and patterns not seen in nature. "We can make custom flies," notes Carroll. By manipulating the gene, "we can make striped flies out of spotted flies."
In addition to working out the molecular details of how the fly colors its wings, Carroll's group was also able to deduce the evolutionary history of wing coloring in Drosophila guttifera.
In short, says Carroll, the patterns found on the wings of Drosophila guttifera came about through the fly's manipulation of the Wingless gene: "It evolved by simply turning this gene on in places where it hadn't been on before."
Although the study was conducted in a lowly fruit fly, the principles uncovered by Carroll's group, he argues, very likely apply to many animals, everything from butterflies to boa constrictors. "This is animal color patterning, how they are generated, how they evolved."
1. Thomas Werner, Shigeyuki Koshikawa, Thomas M. Williams & Sean B. Carroll. Generation of a novel wing colour pattern by the Wingless morphogen. Nature, 2010; DOI: 10.1038/nature08896
Alcathoe's bat, first identified in Greece in 2001 and thought too weak to cross Channel, found in Yorkshire and Sussex
* Martin Wainwright * guardian.co.uk, Tuesday 20 April 2010 15.39 BST
Alcathoe's bat Alcathoe's bat: has defied experts predictions by crossing the Channel. Photograph: PA
A bat the size of a thumbprint has been found for the first time in Britain, after crossing the Channel in defiance of experts' predictions.
Alcathoe's bat is the smallest of Europe's whiskered bats and the most recently discovered. It was identified as a separate species in Greece only in 2001, after tests on the frequency of its radar call, which is used by all bats to navigate and catch prey.
Named after a Greek princess who was changed into a bat after refusing to worship the god Dionysus, or Bacchus, the tiny mammal has been found in caves in North Yorkshire and Sussex. The sites are already celebrated in bat lore and were rigorously checked by ecologists from Leeds and Sheffield universities as part of a bat survey covering Europe.
The Yorkshire cave is hidden in woodland in Ryedale and was home to Britain's last-known colonies of rare barbastelle and lesser horseshoe bats in the 1960s. The Sussex site, also in woodland on the South Downs, is an area known to house a number of other rare bat species.
Both colonies will automatically receive the stringent protection enjoyed by other British bats.
Prof John Altringham of Leeds University said that the bats almost certainly existed elsewhere in the United Kingdom, but had been overlooked because of their close resemblance to other whiskered species.
"Identification based on appearance alone can be difficult even for the expert," he said. "In the end, only some subtle physical differences and Alcathoe's distinctive echo-location call, which terminates at a significantly higher frequency than those of its relatives (43-46khz) makes identification possible without genetic analysis."
Alcathoe was previously thought to be too small and weak to have crossed the Channel, but the survey suggests that the British population may be quite large. The bats were trapped as they flew into underground swarming sites where thousands of bats from many species mate before hibernating for winter.
Brian Walker, wildlife officer for the Forestry Commission in the North York Moors national park, said: "We have some incredibly rich bat habitats here. It was only a few years ago that work locally helped to confirm that the common pipistrelle bat was actually made up of two different species."
The discovery of Alcathoe's bat takes the number of British species to 17, making bats the most diverse of the country's wild mammals.
Diverse: there are at least three distinct species of killer whale (Aquatic Blue Charters)
They may all look similar, but new genetic evidence shows that killer whales, also known as orcas, include several distinct species.
Tissue samples from 139 killer whales from around the world point to at least three distinct species, say researchers in the journal Genome Research.
Researchers had suspected this may be the case. The distinctive black-and-white or grey-and-white mammals have subtle differences in their markings and also in feeding behaviour.
Orcas as a group are not considered an endangered species, but some designated populations of the predators are. A new species designation could change this and affect conservation efforts.
One of the newly designated species preys on seals in the Antarctic while another eats fish, said Phillip Morin of the US National Oceanic and Atmospheric Administration's (NOAA) South-west Fisheries Science Centre in La Jolla, California, who led the research.
His team sequenced the DNA from the whales' mitochondria, a part of the cell that holds just a portion of the DNA. Mitochondrial DNA is passed down with very few changes from mother to offspring.
New sequencing methods finally made it possible to do so, Dr Morin said in a statement.
"The genetic make-up of mitochondria in killer whales, like other cetaceans, changes very little over time, which makes it difficult to detect any differentiation in recently evolved species without looking at the entire genome," he said.
"But by using a relatively new method called highly parallel sequencing to map the entire genome of the cell's mitochondria from a worldwide sample of killer whales, we were able to see clear differences among the species."
The 139 whales whose DNA was sequenced came from the North Pacific, the North Atlantic and Antarctica.
The genetic evidence suggests two different species in Antarctica and also separates out mammal-eating "transient" killer whales in the North Pacific.
Other types of orca may also be separate species or subspecies, but it will take additional analysis to be sure, the researchers said.
NOAA has designated a population of killer whales that lives in the Pacific off the coast of Washington state as endangered.
Long-Distance Journeys out of Fashion? Global Warming May Be Causing Evolutionary Changes in Bird Migration
The locomotory activity (restlessness) of migratory birds can be recorded quantitatively in environment-controlled chambers. Such cages are equipped with movable perches, which are coupled to micro-switches. (Credit: Max Planck Institute for Ornithology)
ScienceDaily (Apr. 23, 2010) — The results of genetic studies on migratory birds substantiate the theory that in the case of a continued global warming, and within only a few generations, migratory birds will -- subject to strong selection and microevolution -- at first begin to fly shorter distances and at a later stage, stop migrating, and will thus become so-called "residents."
In a selection experiment with blackcaps from southwest Germany, Francisco Pulido and Peter Berthold at the Max Planck Institute for Ornithology in Radolfzell were able to show that first non-migratory birds are to be found in a completely migratory bird population after only two generations of directional selection for lower migratory activity. The strong evolutionary reduction in migration distance found in this study is in line with the expected adaptive changes in bird migration in response to environmental alterations caused by climatic change.
The research is published in the Proceedings of the National Academy of Sciences (April 5, 2010).
For generations, humans have been watching flocks of migrating birds flying to their winter quarters in the autumn, and awaiting their loud songs announcing their happy return in the spring. The timing of their migration is adjusted to the availability of resources, such as food and habitats, in the stopover areas as well as in the non-breeding and breeding areas. For migratory birds it is essential to be in the right place at the right time.
For some years, it has been possible to demonstrate using data collected in the wild that some species of migratory birds respond to the increase in temperature and to the subsequent changes in the environment. The blackcap is one of the species where changes in migratory behaviour have been most consistent. Today, blackcaps return to their breeding sites earlier, lay their eggs earlier, and leave us later in the autumn. One population even established a new wintering area in the British Isles, instead of flying all the way to Spain. Because of its large genetic variation, the researchers expected rapid adaptation to altered environmental conditions in this species, which is a model for investigating the evolution of bird migration.
The scientists at the Max Planck Institute for Ornithology wanted to find out what the mechanisms were for adjusting to global warming, whether there were measurable changes in migratory behaviour within a period with a strong temperature increase, and whether these changes, above all the reduced migratory distance, were an individual adjustment to altered environmental conditions, or whether the genetic composition of the populations would change.
During the period 1988 -- 2001, which were years with particularly high temperatures, blackcap nestlings were taken from their nests each year (757 birds in total) and reared by hand in the lab. The seasonal changes in light-dark transition were simulated and the migratory restlessness of the inexperienced young birds was measured in autumn. The duration of their restless behaviour during the night, i.e. the fluttering and hopping along the perch corresponded approximately to the duration of the flight to their winter quarters.
The birds that were taken from their natural habitat during these 14 years showed a significant reduction in their migratory activity. In their natural habitat this would be equivalent to a shortening of flying distance. This reduction, as the researchers were able to prove, was based on a change in the genetic composition of the population, i.e. evolution.
In a second experiment, the scientists simulated the selection process they had observed in nature in the laboratory, but in "time lapse." The birds with the least migratory activity and their offspring were paired over four generations. In order to avoid inbreeding, the researchers paired 50% of this line with birds in their natural habitat that showed a particularly weak migratory restlessness. After two generations, the first "resident" birds were already to be found in this population. Hence, directional selection for lower migratory activity leads to the evolution of partial migratory populations and, finally, to populations that do not leave their breeding areas at all.
The advantages for the birds are obvious: The shortening of migration distance saves energy and time. Moreover, because shorter days, as experienced in more northern wintering areas, induce an advancement of migratory activity and reproduction, birds migrating shorter distances will occupy the best breeding territories and may produce multiple broods in a year. "We assume that the reduction in migration distance is the first and most significant evolutionary mechanism that migratory birds have for adapting to changed climatic conditions," explains Francisco Pulido. "For birds that migrate short to average distances of approximately 1,000 km, and in which migratory behaviour is genetically determined, as is the case with most songbirds, this can be a successful strategy for survival. However, for long-distance migrants, for which successful migration will depend on overcoming ecological barriers such as desert or sea, this mechanism of adaptation cannot work, as a reduction of migration distance would mean spending the winter in a hostile environment, in which they cannot not survive."
1. Francisco Pulido and Peter Berthold. Current selection for lower migratory activity will drive the evolution of residency in a migratory bird population. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.0910361107
Monkeys feast on swarm of locusts By Jody Bourton Earth News reporter
Geladas have been filmed feasting on a swarm of locusts in the highlands of Ethiopia, behaviour rarely seen before.
Scientists recorded the extraordinary scenes with a video camera as millions of desert locusts invaded the grasslands where the geladas live.
The primates are known to feed almost exclusively on grass, so eating insects this way is highly unusual.
The intensive feeding raises concerns that using pesticides to limit locusts can have adverse affects on wildlife.
The study is published in the journal Primates. Fast food
The event occurred in June 2009 on the Guassa Plateau, Ethiopia, located on the western edge of the Great Rift Valley.
Air currents allowed millions of locusts to travel up from from the Rift Valley to the alpine grassland 3500 metres above sea level.
Researchers have been studying gelada monkeys ( Theropithecus gelada ) in this location for years.
The 220 geladas around me uttered a series of screams, suggesting that they were initially afraid of what was happening Dr Peter Fashing California State University, Fullerton, US
"The desert locust invasion at Guassa was the most amazing biological event I have witnessed in 17 years of studying primates in Africa," says Dr Peter Fashing from California State University, Fullerton, California, US.
Dr Fashing describes how a loud humming sound could be heard before the sky began to darken and massive numbers of the pinkish-brown locusts ( Schistocerca gregaria ) appeared.
"The 220 geladas around me uttered a series of screams, suggesting that they were initially afraid of what was happening," Dr Fashing says.
"They then began running rapidly and chaotically in pursuit of the locusts. It was remarkable to see geladas leaping high into the air to catch the locusts or pouncing on the locusts that had landed on the ground."
The researchers write that due to the chaotic nature of the event and the high speed of the animals it was difficult to follow and study individual geladas.
Dr Fashing undertook the research along with Dr Nga Nguyen also from California State University, Fullerton and Dr Norman Fashing of the College of William and Mary, Williamsburg, Virginia, US.
Other species joined the geladas to feed on the locusts, including an extremely rare Ethiopian wolf ( Canis simensis ) and thick-billed ravens ( Corvus crassirostris ).
"Feasting on locusts by geladas is interesting because geladas are known for being extreme dietary specialists," Dr Fashing says.
Geladas are the only primates known to subsist mostly on grass.
Though many birds species have been known to prey and sometimes track desert locusts swarms, little is known about the extent to which other vertebrates feed opportunistically on these insect aggregations.
The scientists explain the large influx of locusts meant animals were able to take the opportunity to switch diet and take advantage of the large source of protein. Poison meal
However, the researchers' amazement is also tempered with concern.
"While, on the surface, the locust invasion at Guassa was a huge source of protein for the animals who ate them, our concern is that desert locusts are still primarily treated with pesticides in most of Africa, including Ethiopia when outbreaks occur," Dr Fashing says.
That means these pesticides may be passed onto species such as geladas or Ethiopian wolves, as not all of the locusts die during spraying operations.
"We have to be concerned about possible adverse affects that pesticide spraying might have on some of Ethiopia's most spectacular endemic wildlife," Dr Fashing says.
"Indeed, Ethiopian wolves and geladas are the two main flagship species for the conservation of the threatened Ethiopian Highlands ecosystem."
Increases to locust swarm activity in the highlands due to possible changes in climate could also make the situation worse.
"Desert locust invasions have never before been reported at elevations anywhere near as high as at Guassa," Dr Fashing says.
"We cautiously raise the issue in the paper of whether the invasion that occurred at Guassa could be linked to global warming.
"Only time will tell based on whether more desert locust invasions are reported in the future in the Ethiopian Highlands."
Page last updated at 7:55 GMT, Wednesday, 5 May 2010 8:55 UK
By Rebecca Morelle Science reporter, BBC News
A naked mole rat, one of the world's strangest mammals "They look a bit like a sabre-toothed sausage," says Dr Chris Faulkes, as we enter the naked mole rat laboratory at Queen Mary, University of London.
Scuttling around in a maze of tubes are dozens of small rodents. They appear to be hairless, covered with wrinkly, pink skin and they have beady, black eyes. But the thing that really catches your attention is their enormous, protruding teeth.
At first glance, it's clear that Dr Faulkes' description is spot on.
"It's a really, really bizarre looking animal," admits the scientist, who has spent the past 20 years studying naked mole rats.
These rodents, which belong to the African mole rat family, are found in parts of Kenya, Ethiopia and Somalia.
They live in huge underground burrows, which goes some way to explaining why these creatures look like they do - they use their giant teeth to help them dig.
Dr Faulkes says: "They are amazingly well adapted to living underground."
Busy as a bee
But it isn't just their unusual appearance that attracts attention: their behaviour is about as strange as it gets in the mammalian world.
For a start, these little creatures live in huge groups. On average, you will find colonies made up of 80-100 individuals, but sometimes they can grow to a 300-strong group.
More bizarre still is their social structure.
Dr Faulkes points to a mole rat that looks almost twice as large as any nearby. And it is clearly pushing around some of its punier companions.
"That's the queen," he says. "Even in these really huge colonies, there is only a single female that breeds. And she mates with one or two, or sometimes three, breeding males.
"And then the rest of the colony, of both sexes, have their reproduction suppressed and never ever breed."
But the sex-free mole rats have another job, he explains.
"The small ones tend to act as workers, so they carry out colony maintenance activities," says Dr Faulkes.
The larger animals seem to adopt a more defensive role, he adds, keeping predators, such as snakes, at bay.
And if this kind of set up sounds rather familiar, that's because it is.
Dr Faulkes explains: "They behave like the mammalian equivalent of a social insect - they have many, many similarities with bees, ants, wasps and termites."
Throw in on top of this the fact that naked mole rats also live for an unfeasibly long time for a small rodent - 30 years in captivity - and that they also seem to be resistant to cancer, so it is easy to see why scientists are so interested in them.
"There are so many aspects of their biology that are extreme," says Dr Faulkes.
The scientist and his colleagues in Pretoria and at King's College London have used this as the basis to find out what lies behind the naked mole rats' behaviour, and in turn, to start to look at how this might relate to other mammals - including humans.
And one way that they have been doing this is to compare naked mole rats with another member of the African mole rat family, the Cape mole rat.
Where the naked mole rat is a highly social animal and forms long-term social bonds, especially between the queen and her select suitors, the Cape mole rat is solitary and aggressive, and sexually, rather promiscuous.
Dr Faulkes says: "They represent both ends of the spectrum in sociability."
Earlier research carried out on voles had suggested that differences in the way that two hormones, oxytocin and vasopressin, were expressed could make a huge impact on social behaviour, including determining whether a species was likely to be monogamous or promiscuous.
So the team decided to look at whether these hormones could also be linked to the differences in behaviour between the two mole rat species.
Dr Faulkes explains: "We found that the naked mole rats and the Cape mole rats had substantially different patterns.
"The solitary, highly aggressive Cape mole rats had their oxytocin receptors distributed in a different part of the brain to the naked mole rats, while the naked mole rats' oxytocin receptors were found in the same region as monogamous voles."
He added: "This is really telling us that these kinds of systems of differing patterns of distribution for the oxytocin receptors are an important part of what underlies different kinds of social behaviour across mammals."
And while this research has focussed on mole rats, other research groups have been looking at the effects of these hormones on humans, including a recent study that suggested men who inhaled oxytocin became as empathetic as women.
Dr Faulkes says: "It seems even in humans that such changes can actually alter human reproductive behaviour, such as how stable relationships are.
"Some people have even linked mutations in the oxytocin receptor gene to certain types of autism." Big questions Naked mole rat (SPL) The mole rat could help us to answer many questions
But scientists are not just looking at social behaviour. They also think that naked mole rats could help us to sniff out answers to a whole host of questions linked to the human condition.
Some researchers are trying to find out whether the animals hold the key to longevity; others are looking at the clues they might give us in the fight against cancer; while some scientists want to see if they can help us to answer questions about reproduction and fertility.
Dr Faulkes says: "Although it might seem a bit of a stretch of the imagination to go from a naked mole rat to humans, the underlying biology is very, very similar.
"And they are just so unusual and there are so many aspects of their biology that are extreme that they could help us to extend our knowledge across so many species and disciplines."
The lantern shark's glow is controlled by hormones that "switch on" light-emitting cells in its skin. A study led by Julien Claes from the Catholic University of Louvain in Belgium revealed that the unique light control probably evolved when the sharks colonised deeper, darker waters.