To a mosquito, matchmaking means

Scientists have new insight into the sex lives of the much-maligned mosquitoes that are responsible for the vast majority of malaria deaths, as per a report published online on December 31st in Current Biology, a Cell Press publication. In finding a partner of the right species type, male and female mosquitoes depend on their ability to "sing" in perfect harmony. Those tones are produced and varied based on the frequency of their wing beats in flight.

"Everyone must be familiar with the maddening whine a mosquito makes as it hones in for a bite," said Gabriella Gibson of the University of Greenwich at Medway. "There's no doubt a number of of us have wondered why it makes its presence so obvioussurely, after all of these centuries of blood-feeding, selection should have favored a more stealthy approach that would leave mosquitoes less vulnerable to the defensive attacks of its unsettled host. Our findings suggest that mosquitoes rely on the sounds they make to attract a mate of the right species, a behavior that is far more vulnerable to selection than avoiding the risk of being squashed by the rare host that is still awake at feeding time".

The Anopheles gambiae mosquitoes in fact include a considerable amount of genetic diversity, representing a complex of seven species and several chromosomal forms. And that diversity comes with real consequences for humans, explained Gibson and Ian Russell of the University of Sussex. The complexity of malaria epidemiology and control is due in part to the mosquito's remarkable genetic plasticity, enabling its adaptation to a widening range of human-influenced habitats.

The new results help to explain how those different mosquito forms manage to reproductively isolate themselves and maintain that genetic diversity, even while some, including the "M" and "S" forms found in Burkina Faso that were the subject of the current study, can be found traveling together in the very same swarms.

Gibson and Russell's team first discovered that male and female mosquitoes harmonize with each other. Gibson said that this is analogous to two partially deaf singersone alto and the other sopranowho can hear low frequencies, but perhaps not their own or each other's songs. Instead, they listen to the terrible dissonance if one or the other goes a bit sharp or flat, which they can get rid of by adjusting their respective tones until the dissonance diminishes to nothing.

"They can do this even if they each sing a different note, say a 'middle C' and a 'G' four tones higher," Russell said. "By listening and subtly altering their pitch to minimize the dissonance, they achieve their goal of 'singing' in a perfect harmony that we, but not they, can hear".

The scientists have now shown that two mosquitoes don't harmonize successfully if they are of the same sex or if they are not the same type of mosquito. They might try for a while, Gibson explained, but they never find that harmony and eventually give up trying.

And that leads Gibson to another take-home of the study. "Even the most 'lowly creatures,' such as mosquitoes, have highly evolved neurosensory systems that can process relatively simple auditory inputs to produce motor outputs enabling them to distinguish between other types of mosquito that are so closely related we need to analyze their DNA to tell them apart".

Nervous culprit found for Tassie devil facial tumor disease

Cells that protect nerves are the likely origin of the Devil Facial Tumour Disease (DFTD) that has been devastating Australia's Tasmanian devil population, an international team of researchers has discovered.

Devil Facial Tumour Disease (DFTD) is a transmissible cancer that affects only Tasmanian devils and was first reported in 1996. It is spread by biting and quickly kills the animals. The disease is characterised by large tumours, mostly on the face and mouth, which often spread to internal organs.

The research collaboration, led by Australian scientists, has observed that DFTD originates from cells called Schwann cells, which protect peripheral nerve fibres.

The results have been published recently in the international journal Science
Through the discovery, the team has now identified a genetic marker that could be used to accurately diagnose the perplexing cancer, which has seen the devil listed as endangered and facing extinction.

Main author Dr Elizabeth Murchison from the Australian National University said the Schwann cell discovery was significant as there are currently no specific diagnostic tests, therapys or vaccines available for the disease.

"We took biopsies from devil tumours and extracted genetic data from them," Dr Murchison said.

Dr Tony Papenfuss from Melbourne's Walter and Eliza Hall Institute then led the team that determined which genes were switched on in the tumours and identified their genetic signature.

"When we compared the signature of the tumours to other normal tissues we found the tumours were most like Schwann cells," Dr Papenfuss said.

Associate Professor Greg Woods from the University of Tasmania's Menzies Research Institute said the Schwann cell find was an important step in the process to further understand the disease.

"Devils develop tumours of all different types and the genetic markers we have identified are useful for telling apart the tumours that occur in DFTD from other kinds of tumours," Associate Professor Woods said.

The Schwann cell research was conducted as part of the Save the Tasmanian Devil Program's efforts to further explore DFTD. It was supported by the National Health and Medical Research Council and the University of Tasmania's Dr Eric Guiler Tasmanian Devil Research Grant.

From crickets to whales

Researchers who compare insect chirps with ape calls may look like they are mixing aphids and orangutans, but scientists have found common denominators in the calls of hundreds of species of insects, birds, fish, frogs, lizards and mammals that can be predicted with simple mathematical models.

Compiling data from nearly 500 species, researchers with the University of Florida and Oklahoma State University have found the calls of crickets, whales and a host of other creatures are ultimately controlled by their metabolic rates in other words, their uptake and use of energy.

"Very few people have compared cricket chirps to codfish sounds to the sounds made by whales and monkeys to see if there were commonalities in the key features of acoustic signals, including the frequency, power and duration of signals," said James Gillooly, Ph.D., an assistant professor in the department of biology at UF's College of Liberal Arts and Sciences and a member of the UF Genetics Institute. "Our results indicate that, for all species, basic features of acoustic communication are primarily controlled by individual metabolism, which in turn varies predictably with body size and temperature. So, when the calls are adjusted for an animal's size and temperature, they even sound alike".

The finding, reported in today's Proceedings of the Royal Society B, will help researchers understand how acoustic communication evolved across species, uniting a field of study that has long focused on the calls of particular groups of animals, such as birds.

The results also provide insights regarding common energetic and neuromuscular constraints on sound production, and the ecological and evolutionary consequences of producing these sounds.

"Acoustic signals are used to transfer information among species that is mandatory for survival, growth and reproduction," Gillooly said. "This work suggests that this information exchange is ultimately governed by the rate at which an animal takes up and uses energy".

Animal communication is a long-studied area of biology, going back at least to the days of Aristotle. But generally the studies were species-specific, made in the context of courting calls or parental care of a certain type of animal nothing to relate an animal call across a variety of species.

"From my perspective this is one of the first true attempts to provide a general theoretical framework for acoustic communication," said Alexander G. Ophir, Ph.D., an assistant professor of zoology at Oklahoma State, who began the painstaking process of compiling data on animal calls in hundreds of different species while a postdoctoral student at UF. "This seems to provide unifying principles for acoustic communication that can be applied to virtually all species. In terms of producing sounds, we use vocal cords, but other mechanisms of sound production exist, such as insects that rub their legs together. Until now, these sounds have been treated differently. But by providing a general mathematical framework a baseline we have a reference point to compare those differences.

"So if we say one animal's call is loud, we can provide a predictive reference point to say whether it is truly loud when compared with other animal sounds," he said.

That common reference point can even predict what animals long extinct think of Tyrannosaurus rex of "Jurassic Park" fame may have truly sounded like.

"These findings say if you give me information about an animal of a certain body size and the mechanisms it uses to make sounds, I can give you a rough idea of what it sounds like," said Jeffrey Podos, Ph.D., an associate professor of biology at the University of Massachusetts Amherst, who did not participate in the study. "It allows us to imagine where the evolution of acoustic signals might go, and where it might have come from. Further study will probably put these principles in a more explicit evolutionary framework, but this is an interesting idea and presented with such a broad view. I can't think of anyone in at least 30 years who has tied together data from such a diversity of species. These authors are really trying to see the forest instead of the trees".

About salmon migration

A new acoustic telemetry system tracks the migration of juvenile salmon using one-tenth as a number of fish as comparable methods, suggests a paper reported in the January edition of the American Fisheries Society journal Fisheries The paper also explains how the system is best suited for deep, fast-moving rivers and can detect fish movement in more places than other tracking methods.

The Juvenile Salmon Acoustic Telemetry System (JSATS) estimated the survival of young, ocean-bound salmon more precisely than the widely used Passive Integrated Transponder (PIT) tags during a 2008 study on the Columbia and Snake rivers, as per the results of a case study discussed in the paper. The paper also concludes that fish behavior is affected least by light-weight JSATS tags in comparison to larger acoustic tags.

"Fisheries managers and scientists have a number of technologies to choose from when they study fish migration and survival," said main author Geoff McMichael of the Department of Energy's Pacific Northwest National Laboratory.

"JSATS was specifically designed to understand juvenile salmon passage and survival through the swift currents and noisy hydroelectric dams on the Columbia River," McMichael continued. "But other systems might work better in different circumstances. This paper demonstrates JSATS' strengths and helps scientists weigh the pros and cons of the different fish tracking methods available today".

Researchers at PNNL and the U.S. Army Corps of Engineers' Portland District co-authored the paper. PNNL and NOAA Fisheries began developing JSATS for the Corps in 2001.

JSATS is an acoustic telemetry system that includes the smallest available acoustic transmitting tag, which weighs 0.43 grams. Its battery-powered tags are surgically implanted into juvenile salmon and send a uniquely coded signal every few seconds. Receivers are strategically placed in waterways to record the signal and track when and where tagged fish travel. A computer system also calculates the precise 3-D position of tagged fish using data gathered by the receivers.

PIT tags are also implanted into juvenile salmon for migration and survival studies, but don't use batteries to actively transmit signals. Instead, PIT tags send signals when they become energized while passing by PIT transceiver antennas.

For the paper's case study, scientists implanted 4,140 juvenile Chinook salmon with both JSATS and PIT tags. They also placed just PIT tags inside another 48,433 juveniles. All of the case study's tagged fish were released downstream of Lower Granite Dam on the Snake River in April and May 2008.

A significantly greater percentage of JSATS tags were detected than PIT tags, the case study demonstrated. For example, about 98 percent of JSATS-tagged fish were detected at Ice Harbor Dam on the Snake River. About 13 percent of PIT-tagged fish were detected in the same stretch of river. As a result, studies using JSATS require using roughly one-tenth as a number of fish as those employing PIT tags, which helps further conserve the salmon population.

Survival estimates were similar between JSATS and PIT tags. Forty-eight percent of the JSATS-tagged fish were estimated to have survived migration between Lower Granite Dam and Bonneville Dam, which is the last dam on the Columbia before the Pacific Ocean. For PIT-tagged fish, 43 percent were estimated to have reached the same area.

Having flexibility in where receivers can be placed is advantageous, the authors reported. JSATS receivers can be located in both rivers and dams, while PIT antennas commonly can only go inside fish bypasses at dams. Scientists can estimate fish survival for an entire river system when receivers are placed in more locations, the paper explains.

The team also compared JSATS' technical features with those of another acoustic telemetry system, the VEMCO system being used for the Pacific Ocean Shelf Tracking (POST) project along North America's West Coast. The VEMCO system is best suited for use in the slow-moving, open ocean when observing small numbers of large fish, the authors wrote. In contrast, JSATS was developed to study the migration of larger quantities of small juvenile fish in fast-moving rivers.

A key difference between the JSATS and VEMCO systems is dry tag weight. JSATS tags weigh 0.43 grams and are the smallest acoustic tags available. VEMCO tags that have been used in Columbia River juvenile salmon weighed 3.1 grams. Prior research shows fish can bear a tag that weighs up to 6.7 percent of their body weight without significant adverse survival effects. That means JSATS tags can be implanted into fish as light as 6.5 grams, while VEMCO tags should be used in fish that weigh no less than 46.3 grams.

Another advantage of JSATS is that it is non-proprietary and available for anyone to manufacture or use. Because several companies have been able to competitively bid for the opportunity to produce the system's components, its cost has dropped in recent years. JSATS tags, for example, have gone from $300 per tag in 2005 to $215 in 2008. And JSATS tags cost $40 to $135 less than other commercially available acoustic tags in 2008. Proprietary interests have hindered the development of acoustic telemetry equipment in certain areas, the team wrote.

"JSATS has helped us get a clearer, more complete picture of how salmon migrate and survive through the Columbia and Snake rivers to the Pacific Ocean," McMichael said. "But we're continuing to develop JSATS and hope others will find it useful in studies of other aquatic animals. There's an opportunity for all aquatic telemetry technologies to be improved".

Cricket as an orchid pollinator

An orchid researcher based on the island of Reunion in the Indian Ocean and collaborating with scientists at the Royal Botanic Gardens, Kew (RBG Kew) has used motion sensitive night cameras to capture the first known occurrence of a cricket functioning as a pollinator of flowering plants. Not only is this the first time this behaviour has been documented in a member of the Orthoptera order of insects who are better known for eating plants but the 'raspy cricket' is also entirely new to science. The discovery is revealed in a paper published recently (12 January 2010) in Annals of Botany
In 2008 Claire Micheneau, a RBG Kew-associated PhD student studying how the epiphytic orchid genus Angraecum has adapted to different pollinators on Reunion Island, and Jacques Fournel, her collaborator, shot the remarkable footage. It shows a raspy cricket (Glomeremussp) carrying pollen on its head as it retreats from the greenish-white flowers of Angraecum cadetii
The genus Angraecum is best known for Darwin's study of the comet orchid, Angraecum sesquipedale of Madagascar, and his hypothesis that it was pollinated by a bizarre, long-tongued moth pollinator a theory that was later proved to be true a number of years after his death.

Says Claire Micheneau, "We knew from monitoring pollen content in the flowers that pollination was taking place. However, we did not observe it during the day. That's why we rigged up a night camera and caught this raspy cricket in action. Watching the footage for the first time, and realising that we had filmed a truly surprising shift in the pollination of Angraecum, a genus that is mainly specialised for moth pollination, was thrilling.

"The moths that are the main Angraecum pollinators on Madagascar are not found on Reunion and until we started our research the pollination of this genus on Reunion had always been an open question".

Micheneau's research also revealed that two other species of Reunion Island Angraecumorchids (A. bracteosum and A. striatum) are pollinated by two species of small white eye songbirds (Zosterops borbonicus and Zosterops olivaceus).

She continues, "My studies have shown that the raspy cricket is also a surprisingly efficient pollinator with higher rates of pollination and fruit set in Angraecum cadetii than those recorded in its bird-pollinated sister-species." (1).

There is a close match in size between the raspy cricket's head and Angraecum cadetii's nectar-spur opening (2). These wingless raspy crickets reach the flowers by climbing up the leaves of the orchid or jumping across from neighbouring plants. They use long very long antenna to explore their surroundings.

Just why the raspy cricket developed a taste for orchid nectar is still a key question for Micheneau. "Eventhough crickets are typically omnivorous and eat both plant material and other insects, we think the raspy cricket has evolved to eat nectar to compensate for the general scarcity of other insects on Reunion".

Impacts of Climate and Development

California butterflies are reeling from a one-two punch of climate change and land development, says an unprecedented analysis led by UC Davis butterfly expert Arthur Shapiro.

The new analysis, scheduled to be published online this week in the journal Proceedings of the National Academy of Sciences, gives insights on how a major and much-studied group of organisms is reacting to the Earth's warming climate.

"Butterflies are not only charismatic to the public, but also widely used as indicators of the health of the environment worldwide," said Shapiro, a professor of evolution and ecology. "We found a number of lowland species are being hit hard by the combination of warmer temperatures and habitat loss".

The results are drawn from Shapiro's 35-year database of butterfly observations made twice monthly at 10 sites in north-central California from sea level to tree line. The Shapiro butterfly database is unique in science for its combination of attributes: one observer (which reduces errors), very long-term, multiple sites surveyed often, a large number of species (more than 150), and attendant climatological data.

Shapiro's co-authors include three other UC Davis scientists and two former Shapiro graduate students, including lead analyst Matthew Forister, now an assistant professor of biology at the University of Nevada, Reno.

Their most significant findings:

• Butterfly diversity (the number of different species present) is falling fast at all the sites near sea level. It is declining more slowly or holding roughly constant in the mountains, except at tree line.
• At tree line, butterfly diversity is actually going up, as lower-elevation species react to the warming climate by moving upslope to higher, cooler elevations.
• Diversity among high-elevation butterflies is beginning to fall as temperatures become uncomfortably warm for them and, Shapiro says, "There is nowhere to go except heaven."

Using a battery of statistical approaches, Shapiro and colleagues concluded that climate change alone cannot account in full for the deteriorating low-elevation numbers. Land-use data show that the butterfly losses have been greatest where habitat has been converted from rural to urban and suburban types.

He added that one of the most surprising findings was that ruderal ("weedy") butterfly species that breed on "weedy" plants in disturbed habitats and are highly mobile are actually declining faster than "non-weedy" species -- those that specialize in one habitat type.

This is particularly true in the mountains, where such species do not persist over winter but must recolonize every year from lower altitudes. As their numbers drop in the valleys, fewer are available to disperse uphill, and the rate of colonization drops.

"Butterfly folks generally consider these ruderal species to be 'junk species,' sort of the way bird watchers think of pigeons and starlings," said Shapiro. "So it came as a shock to discover that they were being hit even harder than the species that conservationists are used to thinking about.

"Some of the 'weedy' species have been touted as great success stories, in which native butterflies had successfully adapted to the changed conditions created by European colonization of California. That was the case for a number of decades, but habitat loss has apparently caught up with them now".

The study, "Compounded effects of climate change and habitat alteration shift patterns of butterfly diversity," will be online at http://www.pnas.org. It was funded by the National Science Foundation.

Tilapia feed on Fiji's native fish

The poster child for sustainable fish farmingthe tilapiais actually a problematic invasive species for the native fish of the islands of Fiji, as per a newly released study by the Wildlife Conservation Society and other groups.

Researchers suspect that tilapia introduced to the waterways of the Fiji Islands appears to be gobbling up the larvae and juvenile fish of several native species of goby, fish that live in both fresh and salt water and begin their lives in island streams.

The recently published paper appears in Aquatic Conservation: Marine and Freshwater Ecosystems The authors include: Stacy Jupiter and Ingrid Qauqau of the Wildlife Conservation Society; Aaron P. Jenkins of Wetlands International-Oceania; and James Atherton of Conservation International.

"A number of of the unique freshwater fishes of the Fiji Islands are being threatened by introduced tilapia and other forms of development in key water catchment basins," said Dr. Jupiter, a co-author of the study and one of the researchers examining the effects of human activities on the native fauna. "Conserving the native fishes of the islands will require a multi-faceted collaboration that protects not only the waterways of the islands, but the ecosystems that contain them." .

The most surprising finding of the study centers on the tilapia, a member of the cichlid family of fishes from Africa that has become one of the most important kinds of fish for aquaculture, due in large part to its rapid rate of growth and palatability. Aside from its value as a source of protein, the tilapia is sometimes problematic to native fish species in tropical locations.

To gauge the impacts of tilapia and other human activities on native fish species in the Fiji Archipelago, scientists surveyed the fish species and other denizens of 20 river basins on the major islands of Vitu Levu, Vanua Levu, and Taveuni. In addition to catching and identifying fishes with gill and seine nets, the researchers also rated other environmental factors such as: the potential of erosion due to loss of forest cover and riparian vegetation; road density near rivers and streams; the distances and complexity of nearby mangroves and reefs; and the presence or absence of invasive species (tilapione of the majorly).

The team observed that streams with tilapia contained 11 fewer species of native fishes than those without; species most sensitive to introduced tilapia included the throat-spine gudgeon, the olive flathead-gudgeon, and other gobies. In general, sites where tilapia were absent had more species of native fish.

Since tilapia are known to consume the larvae and juvenile fish, the scientists assume that the introduced species appears to be consuming the native ones as they make their way upstream and down. Absence of forest cover adjacent to streams was also corcorrelation to fewer fish species.

Based on the spatial information compiled in the study, the scientists observed that remote and undeveloped regionswith waterways containing a full complement of native species and no tilapiaon the three islands should be considered priority locations for management. The main management activities, the authors recommend, should include conserving forests around waterways and keeping the tilapia out.

"Protecting marine and aquatic biodiversity takes more than managing isolated rivers or coral reefs," said Dr. Caleb McClennen, Director of the Wildlife Conservation Society's Marine Program. "A holistic conservation approach is needed, one that incorporates freshwater systems, the surrounding forest cover, coastal estuaries and seaward coral reefs. As aquaculture continues to develop worldwide, best practices must include precautionary measures to keep farmed species out of the surrounding natural environment." .

Tracking paw prints of selective breeding

From the Dachshund's stubby legs to the Shar-Pei's wrinkly skin, breeding for certain characteristics has left its mark on the dog genome. Scientists have identified 155 regions on the canine genome that appear to have been influenced by selective breeding.

With more than 400 distinct breeds, dogs come in a wide range of shapes, sizes, fur-styles, and temperaments. The curly-haired toy poodle, small enough to sit in a teacup, barely looks or acts like the smooth-coated Great Dane tall enough to peer like a periscope out of a car's sunroof. Not so apparent are breed differences in how the dogs' bodies function and their susceptibility to various diseases.

Eventhough domestication of dogs began over 14,000 years ago, as per Dr. Joshua Akey, University of Washington (UW) assistant professor of genome sciences, the spectacular diversity among breeds is thought to have originated during the past few centuries through intense artificial selection of and strict breeding for desired characteristics. Akey is the main author of the effort to map canine genome regions that show signs of recent selection and that contain genes that are prime candidates for further investigation. Those genes are being examined for their possible roles in the most conspicuous variations among dog breeds: size, coat color and texture, behavior, physiology, and skeleton structure.

The scientists performed the largest genome-wide scan to date for targets of selection in purebred dogs. The genomes came from 275 unrelated dogs representing 10 breeds that were very unlike each other. The breeds were: Beagle, Border Collie, Brittany, Dachshund, German Shepherd, Greyhound, Jack Russell Terrier, Labrador Retriever, Shar-Pei, and Standard Poodle.

The study was conducted, the scientists said, because the canine genome, the product of centuries of strong selection, contains a number of important lessons about the genetic architecture of physical and behavioral variations and the mechanisms of rapid, short-term evolution. The findings, the scientists said, "provide a detailed glimpse into the genetic legacy of centuries of breeding practices".

Their results were published Jan. 11 in the Proceedings of the National Academy of Science, in the article "Tracking footprints of artificial selection in the dog genome".

The scientists catalogued more than 21,000 tiny variations in the genome. In investigating the relationships among the 10 breeds, they observed that, genetically, the German Shepherd, Shar-Pei, Beagle, and Greyhound were particularly distinct.

Their list of most differentiated regions of the dog genome included five genes already associated with hallmark traits of certain breeds: one for small size, one for short limbs like those in Dachshunds and other stubby-legged dogs, and three for coats.

In calculating the overlap of the signatures marking selection in the genome, the scientists observed that approximately 66 percent occurred in only one or two breeds. They noted it was likely that these genome regions contain genes that confer qualities that distinguish a breed, such as skin wrinkling in the Shar-Pei. In contrast, signatures of selection found in five or more breeds tended to sort the dogs into classes, and include, for example, a gene that governs the miniature size of breeds in the toy group.

A gene linked to dwarfism in mice, the study reports, appears to mediate variations in dog breed size and weight. Small-size breeds, like Dachshund, Beagle, Jack Russell Terrier, and Brittany have enormous differentiation in this gene, in comparison to larger-size breeds. Another region of peak differentiation in the dog genome, in an area thought to regulate muscle cell formation in embryos, seems to separate the German Shepherd, Jack Russell Terrier, Border Collie and Greyhound from the Dachshund, Beagle, Brittany, and Shar-Pei.

The 155 regions of the genome that appear to have been influenced by selective breeding contain 1,630 known or predicted protein-coding genes. The scientists tried to obtain a broad overview of the molecular functions of these genes. The were surprised to discover that genes involved in immunity and defense were overrepresented in the 155 regions, a phenomenon also discovered in genome analysis of selection in natural populations. Natural and artificial selection were not expected to act on similar classes of genes, the scientists noted, but immune-related genes appears to be frequent targets of selection because of their critical role in defending against ever-changing infections.

The scientists honed in on a particular genome region in the Shar-Pei. A number of of these dogs have excessive wrinkles, but some are smooth. The degree of skin folding correlates with levels of certain molecules whose production appears to be governed by a gene in this region. Rare mutations in this same gene also cause severe skin wrinkling in people. Tiny genetic variations in this gene seemed associated with whether a Shar-Pei would be smooth or wrinkled, and a rare genetic mutation was found in the Shar-Pei but not in other dogs.

The scientists explained, that, despite the a number of insights emerging from their data, there were several limitations to their study and in interpreting the findings. They pointed out that a pattern of variation that is unusual to the dog genome at large doesn't prove that specific genome region is under selection.

A major impetus behind studying dog genomics, the scientists pointed out, is its potential to advance knowledge about the genetic basis of human form variations and of differences in disease susceptibility among people. In a number of cases, the scientists said, it appears to be easier to locate the genetic targets of selection in dogs, and then map these to related regions in the human genome. Researchers are intrigued by the possibility that recent selection may have affected genome regions common to both human and dog lineages.

"This research has shown that artificial selection in dogs has acted on a number of of the same genes as natural selection in humans, and that a number of of these genes are regulators of gene activity," said Dr. Irene Eckstrand, who oversees evolution grants at the National Institute of General Medical Sciences at the National Institutes of Health. "The statistical and computational approaches used in this study will be of great value in deciphering the organization of human genetic variation, and in identifying the genetic basis of human characteristics".

The scientists also said that a better understanding of artificial selection in dogs may reveal the molecular mechanisms of rapid, short-term evolution. Future work, they hope, may uncover the gene activities responsible for shaping the incredible diversity among the world's dogs.

Why leopards can't change their spots

The leopard cannot change its spots, nor can the tiger change its stripes, but a new research report reported in the January 2009 issue of the journal GENETICS tells us something about how cats end up with their spots and stripes. It demonstrates for the first time that at least three different genes are involved in the emergence of stripes, spots, and other markings on domestic cats. Scientists have also determined the genomic location of two of these genes, which will allow for further studies that could shine scientific light on various human skin disorders.

"We hope that the study opens up the possibility of directly investigating the genes involved in pattern formation (i.e., the establishment of stripes, spots, and other markings) on the skin of mammals, including their structure, function, and regulation," said Eduardo Eizirik, a researcher involved in the work from the Pontifical Catholic University of Rio Grande do Sul, Brazil. "From these studies, we hope to understand how the different coat patterns have evolved in different mammalian groups, and to be able to investigate their roles in adaptation to different environments, such as their importance for camouflage in wild cat species."

Researchers crossed domestic cats with different coat patterns, such as stripes and blotches, and tracked the inheritance of these patterns among their offspring. Genetic samples were collected and used to type various molecular markers. Results showed that specific markers were inherited by a kitten every time a given coat pattern appeared, suggesting that the marker and the gene causing the coat pattern were located in the same region of the genome. Using statistical procedures called linkage mapping, researchers determined the genomic location of two genes involved in these traits. By clarifying the inheritance of markings in one mammalian species, scientists hope to identify and characterize the implicated genes and then determine if they apply to other mammals, such as humans. The hope is that this discovery will shed new light on human skin diseases that appear to follow standardized patterns.

"Coat color and markings of animals are obvious traits that have long attracted the interest of geneticists" said Mark Johnston, Editor-in-Chief of the journal GENETICS, "and this study in cats may ultimately help us better understand the genetics behind hair and skin color in other mammals. In turn, this understanding could lead to new therapeutic strategies to correct skin problems in people".

Plant-pollinator relationship

Figs and the wasps that pollinate them present one of biologists' favorite examples of a beneficial relationship between two different species. In exchange for the pollination service provided by the wasp, the fig fruit provides room and board for the wasp's developing young. However, wasps do not always pollinate the fig. Fig trees "punish" these "cheaters" by dropping unpollinated fruit, killing the wasp's offspring inside, report scientists working at the Smithsonian Tropical Research Institute.

Their results, reported in theProceedings of the Royal Society, show that sanctions against cheaters appears to be critical to maintain the relationship.

"Relationships require give and take. We want to know what forces maintain this 80-million-year-old arrangement between figs and their wasp pollinators." said main author, Charlotte Jandr, graduate student in Cornell University's Department of Neurobiology and Behavior, who conducted the study as a Smithsonian pre-doctoral fellow. "What prevents the wasps from reaping the benefits of the relationship without paying the costs?".

Some wasp species passively carry pollen that sticks to their bodies. Others actively collect pollen in special pouches. Jandr reviewed the ability of six different fig tree-fig wasp species pairs to regulate cheating. She introduced either a single pollen-free wasp, or a wasp carrying pollen, into a mesh bag containing an unpollinated fig. The wasps entered the figs to lay their eggs. Jandr observed that trees often dropped unpollinated figs before young wasps could mature.

"This is really about the all-too-human theme of crime and punishment. We observed that in actively pollinated fig specieswhen wasps expend time and energy to collect and deposit pollen-- wasps that did not provide the basic service of pollination were sanctioned. However, in passively pollinated specieswhen the wasps do not need to make an effort to pollinate--sanctions were absent," said Allen Herre, STRI staff scientist. "Eventhough we still need to clearly understand the costs linked to applying sanctions, it seems like sanctions were only present where needed." .

"Sanctions seem to be a necessary force in keeping this, and other, mutually-beneficial relationships on track when being part of a mutualism is costly," said Jandr. "In our study, we saw less cheating when sanctions were stronger. Similar results have been found among human societies and in social insects. It is very appealing to believe that the same general principles could help maintain cooperation both within and among species".

Zebrafish helps drug development

By combining the tools of medicinal chemistry and zebrafish biology, a team of Vanderbilt researchers has identified compounds that may offer therapeutic leads for bone-related diseases and cancer.

The findings, reported in ACS Chemical Biology, support using zebrafish as a novel platform for drug development.

In 2007, Charles Hong, M.D., Ph.D., and his colleagues described using fish embryos to screen for compounds that interfere with signaling pathways involved in early development pathways known to play roles in a variety of disease processes. They discovered the compound "dorsomorphin" and demonstrated that it blocked BMP (bone morphogenetic protein) signaling, which has been implicated in anemia, inflammatory responses and bone-related disorders.

But in examining dorsomorphin further, the researchers observed that it had other "off-target" effects it also blocked the VEGF (vascular endothelial growth factor) receptor and disrupted zebrafish blood vessel development, a process called angiogenesis.

"Off-target effects contribute to side effects and limit the therapeutic potential of small molecule signaling inhibitors," said Hong, assistant professor of Medicine and Pharmacology.

To find compounds that were more selective BMP inhibitors (didn't have the off-target effects), Hong and his colleagues opted to use their zebrafish drug discovery screen as a drug development/optimization tool.

Craig Lindsley, Ph.D., director of Medicinal Chemistry for the Vanderbilt Program in Drug Discovery, Corey Hopkins, Ph.D., associate director, and their colleagues used the dorsomorphin "backbone" as a starting point to synthesize a number of different analogs subtly different dorsomorphin-like compounds.

Then Hong and his team tested these compounds for their effects on zebrafish embryonic development.

"We quickly discovered that the two effects of dorsomorphin could be separated some analogs only affected patterning and some only affected angiogenesis," Hong said. The researchers biochemically characterized compounds of both types and found very selective and potent BMP inhibitors and selective VEGF inhibitors.

The zebrafish embryo, Hong said, is very good at assessing a compound's selectivity for a certain signaling pathway. Mixed signals from compounds that are not selective (they hit multiple targets) are toxic to the embryo it "shuts down development".

The team identified a VEGF inhibitor, for example, that outperformed an existing VEGF inhibitor that was being developed for cancer treatment (blocking angiogenesis cuts off the "supply lines" for a growing tumor) but was pulled from development during a Phase III trial.

"If they (the pharmaceutical company) had tested that compound in zebrafish, they would have quickly learned that it wasn't potent or selective," Hong said.

"Using zebrafish is a novel way to do a structure-activity relationship study" a study that examines a series of analog compounds to determine which is the most selective and most potent, he added.

Traditionally, pharmaceutical companies perform these types of studies in vitro, with isolated proteins or cells. But Hong points out that in vitro studies assess only "one dimension" of the biology. Compounds that have great activity in vitro often fail later because they have poor selectivity or because they do not have chemical properties that make them good drugs (they are not "bioavailable").

"The zebrafish assesses selectivity and bioavailability all at the same time," Hong says. "What the traditional approach takes months to do, the zebrafish does in a day".

Because BMP and VEGF inhibitors have therapeutic potential for a variety of diseases, the researchers will begin to test the drug candidates in mouse models.

Hong praised Vanderbilt leaders for putting into place the drug discovery infrastructure that made the work possible.

"Having medicinal chemists and zebrafish biologists together in the same building really fostered our collaboration," he said. "This kind of collaboration would not be likely at the majority of medical institutions".

Sexual reproduction versus asexual reproduction

Living organisms have good reason for engaging in sexual, rather than asexual, reproduction as per Maurine Neiman, assistant professor of biology in the UI College of Liberal Arts and Sciences and researcher in the Roy J. Carver Center for Genomics.

In an article published in a recent issue of the journal Molecular Biology and Evolution, she and her colleagues, including John M. Logsdon Jr., associate professor of biology, examined the theory that sexual reproduction, while requiring more time and energy than asexual reproduction, is also much more common among living organisms and, therefore, must be very beneficial.

The study looked at sexual, as well as asexual, varieties of a New Zealand freshwater snail (left), Potamopyrgus antipodarum, by sequencing mitochondrial genomes and observed that the sexually reproducing snails had accumulated harmful DNA mutations at about half the rate of the asexual snails.

"This is the first study to compare mutation accumulation in a species where sexual individuals and asexual individuals regularly coexist, and thus provides the most direct evidence to date that sex helps to counter the accumulation of harmful mutations," said Neiman.

Neiman plans to continue her evolutionary biology research such that a clearer understanding of the advantages of sex will offer a better understanding of the value of preserving genetic diversity within and among populations, species, and ecological communities.

Parasite of the Day

My colleague at the American Museum of Natural History, Susan Perkins, has started an ambitious new blog. She will be introducing a new parasite to the world each day in Parasite of the Day. Unfortunately, perhaps, for the hosts of the world, Susan has plenty of subject matter and should be busy for quite some time. A recent paper in PNAS (Dobson et al. 2008) states that eventhough they "estimate that there are between 75,000 and 300,000 helminth species parasitizing the vertebrates. [They] have no credible way of estimating how a number of parasitic protozoa, fungi, bacteria, and viruses exist. At least the helminths parasites of vertebrates will keep Susan busy for the next 821 years or so.
The photo above is of Neoechinorhynchus emyditoides a species of acanthocephalan, or thorny-headed worm, by Mike Barger.

Bat researchers no longer flying blind

Midwife toads that live in the mountains are highly likely to die from a serious fungal infection, called chytridiomycosis, whereas their infected relatives in the lowlands are not, as per new research published recently inEcology Letters
The authors of the study, from Imperial College London, the Zoological Society of London and the BiodivERsA project RACE, say their findings suggest conservationists appears to be able to limit the impact of the disease in the mountains by ensuring tourists do not transfer it between lakes.

During the five year study, the scientists observed that no midwife toads at low altitudes died as a result of fungal infection, whereas up to 100 per cent of those at high altitudes died. The mortality rate of toads at high altitudes fluctuated over the five years.

The fungus Batrachochytrium dendrobatidis (Bd), also known as chytrid fungus, grows in the skin of amphibians, causing a disease called chytridiomycosis. The fungus has caused a number of species of frog and toad to become extinct and human activity has spread the fungus across the world, affecting an estimated 50 per cent of amphibian species.

Eventhough infection commonly is invisible to the naked eye, it can cause skin discolouration and ulceration and lead to convulsions. Prior research shows that infection kills amphibians by causing heart failure. The fungus is especially prevalent in Australia and the Americas, where its spread is well studied. However, little was known about Bd in Europe before today's study.

In the newly released study, the scientists found no dead toads at low altitudes. However, in mountain regions up to 100 per cent of infected toads died of the fungus infection, and the disease is known to have caused the extinction of some of the populations in the region. The authors of the study, which was funded by the Natural Environment Research Council and BiodivERsA, say this means it is vital for conservationists to ensure that the fungus does not spread to new mountain ranges, as it could be devastating to the toad populations living there.

In the new research, the researchers studied the spread of Bd in midwife toads (Alytes obstetricians) living on the Iberian Peninsula, which includes Spain and Portugal. Midwife toads are common in Europe and are a vital part of the ecosystem, providing predators with food and preying on insect pests. The newly released study shows that the disease is spread patchily across much of the area but in some locations, such as the Pyrenees, the disease is found in clusters, where it is threatening local toad populations. Eventhough the scientists found no link between the presence of infection and climate, they did show that the disease is much more dangerous for toads living at high altitudes. Eventhough no midwife toads died at low altitudes in the region covered by this study, the disease has been fatal to other amphibian species in lowland areas around the world.

Dr Matthew Fisher, corresponding author of the study from the Department of Infectious Disease Epidemiology at Imperial College London, said: "Chytridiomycosis is a serious problem for amphibians all over the world and the disease is causing extinctions at a shocking rate. At the moment, we have no prevention or cure for Bd infection in the wild so we need to act fast to stop it from spreading to otherwise healthy populations.

"We identified infected midwife toads across the Iberian Peninsula, but the infection was much more likely to be fatal in toads that live at high altitudes, such as in mountain ranges. These areas are often tourist hotspots, and if people are walking along footpaths and visiting different lakes, they appears to be spreading the infection unwittingly.

"In order to limit the devastation this fungus could potentially cause, we need to invest money and expertise in stopping it from spreading. Simple measures, such as disinfecting tourists' boots when they cross infected areas, and providing them with uninfected sources of water so they don't spread fungal spores between lakes appears to be effective ways of tackling this problem. We are also concerned that stocking high-altitude lakes with artificially-reared fish appears to be introducing the disease to uninfected areas, and would like to see further research to investigate whether this is occurring," added Dr Fisher.

For today's study, the scientists took skin swabs of 3016 tadpole and adult midwife toads from 126 locations across the Iberian Peninsula between 2003 and 2008. They analysed the samples in the laboratory, using a sensitive molecular technique called polymerase chain reaction (PCR) and found Bd infection at 31 of the sites.

The scientists looked at the genetic fingerprints of the fungi causing a cluster of infections and deaths in the Pyrenees and found they were all identical. This suggests that the disease was introduced to the area relatively recently.

The scientists then used mathematical models to determine whether environmental factors, such as minimum and maximum temperatures, rainfall and altitude affected the probability of infection or the risk of fatality. The results showed no link between environmental factors and probability of infection, but infected toads living at high altitude were more likely to die as a result of their infection than those living at lower altitudes.

The authors of the study say the increase in risk of mortality could be because the toads are less able to fight off infection in the mountains, where temperatures are colder, or that the fungus is better adapted to cold environments. The scientists now plan to investigate this further.

Environmental threats to blue crabs

The Atlantic blue crab, Callinectes sapidus, long prized as a savory meal at a summer party or seafood restaurant, is a multi-million dollar source of income for those who harvest, process and market the crustacean along the U.S. Atlantic and Gulf coasts. Unfortunately, the blue crab population has been declining in recent years under the assault of viruses, bacteria and man-made contaminants. The signs of the attack often are subtle, so scientists from the National Institute of Standards and Technology (NIST) and the College of Charleston (CofC) are at work trying to identify the clues that will finger specific, yet elusive, culprits.

Pathogens and pollutants impair the blue crab's metabolic processes, the chemical reactions that produce energy for cells. These stresses should cause tell-tale changes in the levels of metabolites, small chemical compounds created during metabolism. Working at the Hollings Marine Laboratory (HML) in Charleston, S.C., the NIST/CofC research team is using a technology similar to magnetic resonance imaging (MRI) to identify and quantify the metabolites that increase in quantity under common environmental stresses to blue crabsmetabolites that could be used as biomarkers to identify the specific sources.

In a recent paper in Metabolomics,* the HML research team describes how it used nuclear magnetic resonance (NMR) spectroscopy to study challenges to one specific metabolic process in blue crabs: oxygen uptake. First, the scientists simulated an environmentally acquired bacterial infection by injecting crabs with the bacterium Vibrio campbellii. This pathogen impairs the crab's ability to incorporate oxygen during metabolism. Using NMR spectroscopy to observe the impact on metabolite levels, the scientists observed that the yield of glucose, considered a reliable indicator of mild oxygen starvation in crustaceans, was raised.

In a second experiment, the HML team mimicked a chemical pollutant challenge by injecting blue crabs with a chemical** known to inhibit oxidative phosphorylation, a metabolic process that manufactures energy. This time, the metabolite showing up in response to stress was lactate, the same compound seen when our muscles need energy and must take in oxygen to get more produced. A rise in the amount of lactate proved that the crabs were increasing their oxygen uptake in response to the chemical exposure.

"Having the glucose and lactate biomarkersand the NMR spectroscopy technique to accurately detect themis important because the blue crab's responses to mild, non-lethal metabolic stresses are often so subtle that they can be missed by traditional analyses," says Dan Bearden, corresponding author on the HML paper.

The Low Calorie Pet Foods

Dog and cat owners buying weight-control diets for their overweight pets are faced with a confusing two hundred percent variation in calorie density, recommended intake, and wide range cost of low-calorie pet foods, as per a research studyby the Cummings School of Veterinary Medicine at Tufts University.

The study, published this month in the Journal of the American Veterinary Medical Association, examined nearly 100 commercially available diets with weight management claims. Among their findings is that dry dog foods range in calorie density from 217 to 440 kilocalories per cup (kcal/cup) and a recommended intake that ranged from 0.73 to 1.47 times the dog's resting energy requirement. The diets also varied wildly in price-from 4 cents to more than $1.10 per kilocalorie.

Similar findings were made in wet dog food (189-398 kcal/can) and cat food (235-480 kcal/cup) marketed for weight control. The results appears to be significant for owners whose cats or dogs are overweight or obese, as per Lisa M. Freeman, DVM, PhD, DACVN, the study's co-author along with 2010 Cummings School graduate Deborah E. Linder, DVM. Nearly 50% of domesticated animals are overweight or obese.

"There is so much information-and misinformation-about pet foods, it's understandable that people are confused about what to feed their dogs and cats," said co-author Dr. Lisa Freeman, professor of nutrition at Tufts University's Cummings School of Veterinary Medicine. "To counteract these myths, people are accustomed to turning to the labels on food-but, as this study shows, packaging might not always be a reliable source of information".

Under federal guidelines, pet foods labeled "lite," "light," "low calorie," "less calorie," or "low calorie" must provide the caloric content. Foods with a light, lite, or low-calorie designation must also adhere to a maximum kilocalorie per kilogram restriction. However, Freeman points out that more than half of the foods reviewed in the study exceeded this maximum. Foods without these designations currently are allowed, but not required, to provide the caloric content on the label. Efforts are currently underway to make this information mandatory on all pet food labels.

Another important issue identified in this study was the high variability in feeding recommendations for weight loss based on the labels that were reviewed. In fact, for most of the diets, pets would not lose weight or would actually gain weight if owners adhered to the labels' feeding directions and did not adjust as per their pet's individual calorie requirements.

Obesity in companion animals is linked to numerous diseases, including pancreatitis, osteoarthritis, dermatologic disease, diabetes, and respiratory tract diseases-and may contribute to a shorter lifespan, as per earlier published studies.

Figs and fig wasps

Figs and fig wasps have evolved to help each other out: Fig wasps lay their eggs inside the fruit where the wasp larvae can safely develop, and in return, the wasps pollinate the figs.

But what happens when a wasp lays its eggs but fails to pollinate the fig?

The findings suggest that when one species in a mutually beneficial relationship fails to hold up its end of the bargain, sanctions appears to be a necessary part of maintaining the relationship.

"We want to know what forces maintain this 80 million-year-old mutualism between figs and their wasp pollinators," said main author Charlotte Jandr, a Cornell graduate student in neurobiology and behavior, who conducted the study as a Smithsonian Tropical Research Institute predoctoral fellow. Edward Allen Herre, a staff scientist at the Smithsonian institute in Panama, co-authored the paper.

"What prevents the wasps from cheating and reaping the benefits of the relationship without paying the costs?" Jandr added.

More than 700 species each of fig trees and wasps have co-evolved in the tropics worldwide, with each fig tree species having its own species of pollinating wasp. Jandr worked on six fig tree-fig wasp pairs for the study. Some wasp species passively carry pollen that sticks to their bodies, while others actively collect pollen in special pouches.

The scientists observed that in passively pollinated pairings, the tree almost never aborted its fruit, and the wasp always carried pollen. However, the scientists observed that in actively pollinated pairings, where the wasp needs to expend energy to collect pollen, the tree dumped the fruit and killed the offspring when the wasps did not carry pollen.

The scientists also observed that among the actively pollinated fig species, pollen-free wasps were much more common when the trees had weak sanctions.

"Sanctions seem to be a necessary force in keeping this and other mutually beneficial relationships on track when being part of a mutualism is costly," said Jandr. "In our study, we saw less cheating when sanctions were stronger. Similar results have been found among human societies and social insects. It is very appealing to believe that the same general principles could help maintain cooperation both within and among species".

Deadly fish virus now found in all Great Lakes

A deadly fish virus that was first discovered in the Northeast in 2005 has been found for the first time in fish from Lake Superior, report Cornell researchers. That means that the virus has now been documented in all of the Great Lakes.

The viral hemorrhagic septicemia virus (VHSV), which causes fatal anemia and hemorrhaging in a number of fish species, poses no threat to humans, said Paul Bowser, professor of aquatic animal medicine at Cornell's College of Veterinary Medicine.

Bowser and his colleagues recently tested 874 fish from seven sites in Lake Superior in collaboration with the U.S. Geological Survey (USGS) Western Fisheries Research Center in Seattle. Fish from Paradise and Skanee in Michigan and St. Louis Bay and Superior Bay in Wisconsin tested positive. Some of the results have been corroborated by other laboratories; others have tests still under way.

The virus, which has been identified in 28 freshwater fish species in the Great Lakes watershed, has reached epidemic proportions in the Great Lakes and threatens New York's sport-fishing industry, said Bowser, estimated to contribute some $1.4 billion annually to New York's economy.

"People come from all over the eastern United States to fish the Great Lakes," said Bowser, noting that the virus has also been found in a few inland waters as well, including lakes, streams and a family-owned earthen pond. "The economy of a number of of these areas ebbs and flows with the season and perceived value of outdoor recreational opportunities. The value of these opportunities is dependent on how successful we are at managing the health of wild fish. On a worldwide basis, VHSV is considered one of the most serious pathogens of fish, because it kills so a number of fish, is not treatable and infects a broad range of fish species".........

The Low Calorie Pet Foods

Dog and cat owners buying weight-control diets for their overweight pets are faced with a confusing two hundred percent variation in calorie density, recommended intake, and wide range cost of low-calorie pet foods, as per a research studyby the Cummings School of Veterinary Medicine at Tufts University.

The study, published this month in the Journal of the American Veterinary Medical Association, examined nearly 100 commercially available diets with weight management claims. Among their findings is that dry dog foods range in calorie density from 217 to 440 kilocalories per cup (kcal/cup) and a recommended intake that ranged from 0.73 to 1.47 times the dog's resting energy requirement. The diets also varied wildly in price-from 4 cents to more than $1.10 per kilocalorie.

Similar findings were made in wet dog food (189-398 kcal/can) and cat food (235-480 kcal/cup) marketed for weight control. The results appears to be significant for owners whose cats or dogs are overweight or obese, as per Lisa M. Freeman, DVM, PhD, DACVN, the study's co-author along with 2010 Cummings School graduate Deborah E. Linder, DVM. Nearly 50% of domesticated animals are overweight or obese.

"There is so much information-and misinformation-about pet foods, it's understandable that people are confused about what to feed their dogs and cats," said co-author Dr. Lisa Freeman, professor of nutrition at Tufts University's Cummings School of Veterinary Medicine. "To counteract these myths, people are accustomed to turning to the labels on food-but, as this study shows, packaging might not always be a reliable source of information".........

Environmental threats to blue crabs

The Atlantic blue crab, Callinectes sapidus, long prized as a savory meal at a summer party or seafood restaurant, is a multi-million dollar source of income for those who harvest, process and market the crustacean along the U.S. Atlantic and Gulf coasts. Unfortunately, the blue crab population has been declining in recent years under the assault of viruses, bacteria and man-made contaminants. The signs of the attack often are subtle, so scientists from the National Institute of Standards and Technology (NIST) and the College of Charleston (CofC) are at work trying to identify the clues that will finger specific, yet elusive, culprits.

Pathogens and pollutants impair the blue crab's metabolic processes, the chemical reactions that produce energy for cells. These stresses should cause tell-tale changes in the levels of metabolites, small chemical compounds created during metabolism. Working at the Hollings Marine Laboratory (HML) in Charleston, S.C., the NIST/CofC research team is using a technology similar to magnetic resonance imaging (MRI) to identify and quantify the metabolites that increase in quantity under common environmental stresses to blue crabsmetabolites that could be used as biomarkers to identify the specific sources.

In a recent paper in Metabolomics,* the HML research team describes how it used nuclear magnetic resonance (NMR) spectroscopy to study challenges to one specific metabolic process in blue crabs: oxygen uptake. First, the scientists simulated an environmentally acquired bacterial infection by injecting crabs with the bacterium Vibrio campbellii. This pathogen impairs the crab's ability to incorporate oxygen during metabolism. Using NMR spectroscopy to observe the impact on metabolite levels, the scientists observed that the yield of glucose, considered a reliable indicator of mild oxygen starvation in crustaceans, was raised.........

Bees recognize human faces

Going about their day-to-day business, bees have no need to be able to recognise human faces. Yet in 2005, when Adrian Dyer from Monash University trained the fascinating insects to associate pictures of human faces with tasty sugar snacks, they seemed to be able to do just that. But Martin Giurfa from the Universit de Toulouse, France, suspected that that the bees weren't learning to recognise people. 'Because the insects were rewarded with a drop of sugar when they chose human photographs, what they really saw were strange flowers. The important question was what strategy do they use to discriminate between faces,' explains Giurfa. Wondering whether the insects might be learning the relative arrangement (configuration) of features on a face, Giurfa contacted Dyer and suggested that they go about systematically testing which features a bee learned to recognise to keep them returning to Dyer's face photos.

Teaming up with Aurore Avargues-Weber, the team first tested whether the bees could learn to distinguish between simple face-like images. Using faces that were made up of two dots for eyes, a short vertical dash for a nose and a longer horizontal line for a mouth, Avargues-Weber trained individual bees to distinguish between a face where the features were cramped together and another where the features were set apart. Having trained the bee to visit one of the two faces by rewarding it with a weak sugar solution, she tested whether it recognised the pattern by taking away the sugar reward and waiting to see if the bee returned to the correct face. It did.

So the bees could learn to distinguish patterns that were organised like faces, but could they learn to 'categorize' faces? Could the insects be trained to classify patterns as face-like versus non-face like, and could they decide that an image that they had not seen before belonged to one class or the other? To answer these questions, Avargues-Weber trained the bees by showing them five pairs of different images, where one image was always a face and the other a pattern of dots and dashes. Bees were always rewarded with sugar when they visited the face while nothing was offered by the non-face pattern. Having trained the bees that 'face-like' images gave them a reward, she showed the bees a completely fresh pair of images that they had not seen before to see if the bees could pick out the face-like picture. Remarkably they did. The bees were able to learn the face images, not because they know what a face is but because they had learned the relative arrangement and order of the features.

But how robust was the bees' ability to process the "face's" visual information? How would the bees cope with more complex faces? This time the team embedded the stick and dot faces in face-shaped photographs. Would the bees be able to learn the arrangements of the features against the backgrounds yet recognise the same stick and dot face when the face photo was removed? Amazingly the insects did, and when the team tried scrambling real faces by moving the relative positions of the eyes, nose and mouth, the bees no longer recognised the images as faces and treated them like unknown patterns.

So bees do seem to be able to recognise face-like patterns, but this does not mean that they can learn to recognise individual humans. They learn the relative arrangements of features that happen to make up a face-like pattern and they may use this strategy to learn about and recognize different objects in their environment.

What is really amazing is that an insect with a microdot-sized brain can handle this type of image analysis when we have entire regions of brain dedicated to the problem. Giurfa explains that if we want to design automatic facial recognition systems, we could learn a lot by using the bees' approach to face recognition.

New light on our earliest fossil ancestry

Decaying corpses are commonly the domain of forensic scientists, but palaeontologists have discovered that studying rotting fish sheds new light on our earliest ancestry.

The researchers, from the Department of Geology at the University of Leicester, devised a new method for extracting information from 500 million year old fossils -they studied the way fish decompose to gain a clearer picture of how our ancient fish-like ancestors would have looked. Their results indicate that some of the earliest fossils from our part of the tree of life may have been more complex than has previously been thought.

Their findings have been published recently, Sunday Jan 31, ahead of print in Advance Online Publication (AOP) of the science journal Nature on www.nature.com The work was funded by the Natural Environment Research Council (NERC).

Dr Rob Sansom, main author of the paper explains: "Interpreting fossils is in some ways similar to forensic analysis we gather all the available clues to put together a scientific reconstruction of something that happened in the past. Unlike forensics, however, we are dealing with life from millions of years ago, and we are less interested in understanding the cause or the time of death. What we want to get at is what an animal was like before it died and, as with forensic analysis, knowing how the decomposition that took place after death altered the body provides important clues to its original anatomy."

This is something that palaeontologists sometimes overlook, as per Sansom, "probably because spending hundreds of hours studying the stinking carcasses of rotting fish is not something that appeals to everyone." But the rewards are worth the discomfort.

Fish-like fossils from half a billion years ago are recognised as being part of our evolutionary history because they possess characteristic anatomical features, such as a tail, eyes and the precursor of a backbone. Sansom continues: "It seems contradictory, but decomposition is an important part of the process by which animals become preserved and fossilized, so by knowing how these important anatomical features change as they rot, we are better able to correctly interpret the most ancient fossils representing the lowest branches of our part of the evolutionary tree".

"These fossils provide our only direct record of when and how our earliest vertebrate ancestors evolved" adds Dr Mark Purnell, one of the leaders of the study. "Did they appear suddenly, in an evolutionary explosion of complexity, or gradually over millions of years? What did they look like? in what ways did they differ from their worm-like relatives and how did this set the stage for later evolutionary events? Answers to these fundamental questions - the how, when and why of our own origins - remain elusive because reading the earliest vertebrate fossil record is difficult."

The scarcity of branches in this part of the evolutionary tree could reflect rapid, explosive evolution or the simple fact that, because they lacked bones or teeth, the earliest vertebrates left few fossils.

This is the area in which Dr Sarah Gabbott, who with Purnell conceived the Leicester study, is an expert: "Only in the most exceptional circumstances do soft-tissues, such as eyes, muscles and guts, become fossilized, yet it is precisely such remains that we rely on for understanding our earliest evolutionary relatives: half-a-billion years ago it's pretty much all our ancestors had".

The results published recently in Nature, show that some of the characteristic anatomical features of early vertebrate fossils have been badly affected by decomposition, and in some cases may have rotted away completely. Knowing how decomposition affected the fossils means our reconstructions of our earliest ancestors will be more scientifically accurate.