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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".
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.
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".
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
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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 (Glomeremus sp) 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
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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
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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
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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
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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
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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 the Proceedings of the Royal Society, show that sanctions against cheaters appears to be critical to maintain the relationship
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