19 October 2007
Corals spawning at night on the Great Barrier Reef
(caption & photo: ARC Centre of Excellence for Coral Reef Studies
…press release from ARC Centre of Excellence for Coral Reef Studies (CoECRS):
19 October 2007
Key Found To Moonlight Romance
An international team of Australian and Israeli researchers has discovered what could be the aphrodisiac for the biggest moonlight sex event on Earth.
An ancient light-sensitive gene has been isolated by researchers from the ARC Centre of Excellence for Coral Reef Studies (CoECRS) that appears to act as a trigger for the annual mass spawning of corals across a third of a million square kilometres of Australia’s Great Barrier Reef, shortly after a full moon.
The genes, known as a cryptochromes, occur in corals, insects, fish and mammals - including humans - and are primitive light-sensing pigment mechanisms which predate the evolution of eyes.
In a new paper published in the international journal Science today, the team, headed by Marie Curie Scholar Dr Oren Levy of CoECRS and the University of Queensland, reports its discovery that the Cry2 gene, stimulated by the faint blue light of the full moon, appears to play a central role in triggering the mass coral spawning event, one of nature’s wonders.
Professor Ove Hoegh-Guldberg, who leads the University of Queensland laboratory in which the genes were discovered, said “This is the key to one of the central mysteries of coral reefs. We have always wondered how corals without eyes can detect moonlight and get the precise hour of the right couple of days each year to spawn.”
What allows corals to spawn simultaneously along the immense length of the Great Barrier Reef - and also in other parts of the world - has been a scientific mystery till now, though researchers knew that tide, water temperature and weather conditions played a part, says Dr Levy. However the remarkable synchronisation of spawning occurring all along the Reef immediately following a full moon suggested that moonlight was a key factor.
Exposing corals to different colours and intensities of light and sampling live corals on reefs around the time of the full moon, Dr Levy found the Cry2 gene at its most active in Acropora corals during full moon nights. “We think these genes developed in primitive life forms in the Precambrian, more than 500 million years ago, as a way of sensing light,” he explains. “The fact they are linked with the system that repairs damage from ultraviolet (UV) radiation suggests they may evolved in eyeless creatures which needed to avoid high daytime UV by living deep in the water, but still needed to sense the blue light shed by the moon to synchronise their body clocks and breeding cycles.” “They are, in a sense, the functional forerunners of eyes,” Professor Hoegh-Guldberg said.
In humans, cryptochromes still operate as part of the circadian system that tunes us to the rhythms of our planet, though their light-sensing function appears lost to us, he went on to explain.
“They play important roles in regulating the body-clocks of many species, from corals to fruit flies, to zebra fish and mice. The proteins they produce are similar to those in humans and other mammals, though they appear to function more like those in the fruit fly,” says Professor David Miller of CoECRS and JCU.
The coral cryptochrome genes were initially identified by Dr Levy and Dr Bill Leggat working with Professor Hoegh-Guldberg (UQ) on Heron Island. Prof. Miller and Dr David Hayward, of the Australian National University, were able to add information on the coral cryptochromes from a large library of coral genes that they have been compiling (so far they have catalogued about 10,000 out of an estimated 20-25,000 genes in coral), and leading circadian clock biologists from Bar-Ilan and Tel-Aviv Universities in Israel played important roles in interpreting the data.
“Many of these genes developed in deep time, in the earliest phases of organised life on the planet,” Dr Leggat says. “They were preserved for hundreds of millions of years before being inherited by corals when they developed about 240 million years ago, and are still found today in modern animals and humans. They are an indicator that corals and humans are in fact distant relatives, sharing a common ancestor way back.”
Whether they have anything at all to do with human associations between the full moon and romance is not known, but cryptochromes probably still play a part in our body clock.
Link to Full Text of the Paper
18 October 2007
…press release from: Texas A&M University
Researchers studying how singing bats communicate
COLLEGE STATION, Oct. 18, 2007 – Bats are the most vocal mammals other than humans, and understanding how they communicate during their nocturnal outings could lead to better treatments for human speech disorders, say researchers at Texas A&M University.
Thousands of bats native to Central Texas fly overhead each night singing songs of complex syllables – but at frequencies too high for humans to hear.
Texas A&M researcher Michael Smotherman is trying to understand how Mexican Freetail bats organize syllables into songs and how their communication is linked to the brain. “If we can identify those areas in a bat brain [responsible for communication], we can learn more about how a normal [human] brain generates and orchestrates complex communication sequences,” Smotherman says. “And by understanding how that works, we can then come up with testable hypotheses about what might be going on in speech disorders.”
The researchers in Smotherman’s lab are studying two aspects of bat communication. In behavioral studies, they examine sex differences and seasonal variations in communication, and in physiology studies they try to locate the parts of the bat brain active during communication.
Mexican Freetail bats sing mostly in ultrasonic frequencies that are right above the upper limit of human hearing. Humans can sometimes hear little bits of bat songs, however, when parts of syllables drop low enough.
Bats communicate at such high frequencies because of their ability to echolocate, which means they project sound and use the echoes to determine the direction and distance of objects. As the frequency of the bat’s sound gets higher, it can detect a more detailed picture of its surroundings.
Smotherman says Mexican Freetail bats use between 15 and 20 syllables to create calls. Every male bat has its own unique courtship song. The pattern of all courtship songs is similar, but each male bat uses a different syllable in its distinctive song. Bats also use sophisticated vocal communication to draw territorial borders, define social status, repel intruders, instruct offspring and recognize each other.
“No other mammals besides humans are able to use such complex vocal sequences to communicate,” Smotherman says.
The songs bats sing are similar to bird songs. Scientists have understood the link between bird songs and the bird brain for years, but “the architecture of a bird brain is very different from that of a mammal brain,” Smotherman explains, “so it is difficult to apply knowledge about bird communication to human speech.”
The brains of all mammals are organized in basically the same way, so a bat brain has many of the same structures as a human brain. This makes it easier to infer things about human speech from studying bat communication. The researchers’ first goal is to locate the part of the bat brain responsible for singing. “The bat brain has to have some higher vocal center that’s responsible for organizing these [vocal] sequences and patterns, and we just don’t know where it is yet,” Smotherman says. “So we’re using molecular techniques to identify which regions of the brain are most active during singing.”
Smotherman and his team maintain about 75 bats in their lab. They usually collect the bats from schools and churches that report bats in their buildings. “[By doing this,] we don’t have to feel like we’re taking them out of the wild,” Smotherman says. He adds that the bats are not aggressive and are a “fantastic bat for the lab because they are quite friendly.”
Smotherman hopes that over the next decade, the group can apply its research to knowledge of human speech and help shed light on language disorders. “The fact that human speech is so unique has really constrained research in this area,” Smotherman says. “Compared to other areas of neuroscience, we’re way behind in understanding even the most basic issues of how [speech] works.”
17 October 2007
UCSB researchers discover the dawn of animal vision
(Santa Barbara, Calif.) -- By peering deep into evolutionary history, scientists at the University of California, Santa Barbara have discovered the origins of photosensitivity in animals.
The findings are published in this week’s issue of the scientific journal PLoS ONE. The scientists studied the aquatic animal Hydra, a member of Cnidaria, which are animals that have existed for hundreds of millions of years. The authors are the first scientists to look at light-receptive genes in cnidarians, an ancient class of animals that includes corals, jellyfish, and sea anemones.
“Not only are we the first to analyze these vision genes (opsins) in these early animals, but because we don’t find them in earlier evolving animals like sponges, we can put a date on the evolution of light sensitivity in animals,” said David C. Plachetzki, first author and a graduate student at UC Santa Barbara. The research was conducted with a National Science Foundation dissertation improvement grant.
“We now have a time frame for the evolution of animal light sensitivity. We know its precursors existed roughly 600 million years ago,” said Plachetzki.
Senior author Todd H. Oakley, assistant professor of biology at UCSB, explained that there are only a handful of cases where scientists have documented the very specific mutational events that have given rise to new features during evolution.
Oakley said that anti-evolutionists often argue that mutations, which are essential for evolution, can only eliminate traits and cannot produce new features. He goes on to say, “Our paper shows that such claims are simply wrong. We show very clearly that specific mutational changes in a particular duplicated gene (opsin) allowed the new genes to interact with different proteins in new ways. Today, these different interactions underlie the genetic machinery of vision, which is different in various animal groups.”
Hydras are predators, and the authors speculate that they use light sensitivity in order to find prey. Hydra use opsin proteins all over their bodies, but they are concentrated in the mouth area, near the tip of the animal. Hydras have no eyes or light-receptive organs, but they have the genetic pathways to be able to sense light.
16 October 2007
LSU professor studies army-ant-following birds
Certain tropical birds entirely dependent on ant swarms to flush out prey
BATON ROUGE – In the jungles of Central and South America, a group of birds has evolved a unique way of finding food – by following hordes of army ants and letting them do all the work.
Robb Brumfield, assistant curator of genetic resources at the LSU Museum of Natural Science and assistant professor of biological sciences, first witnessed this peculiarity in 1989 when he accompanied then-LSU graduate student Ken Rosenberg to Peru as an assistant.
“Rosenberg’s project investigated dead-leaf-foraging, which is a specialized way that some tropical bird species have devised to find food. These species find their insect prey by probing dead, curled leaves suspended in vine tangles,” Brumfield said. But as he walked endless jungle trails each day in search of these dead-leafing birds, he became captivated by another novel approach some applied to hunting for food: army-ant following.
With this type of specialization, flocks of birds track army-ant swarms through the forest. “When millions of these army ants are on the move, they consume every insect, spider and lizard they come across,” said Brumfield. “Naturally, any animal that hears them coming – and they’re very, very loud – runs the other way. The army-ant-following birds have learned to take advantage of the swarm by perching above it and preying on insects and other small animals trying to escape. It’s reminiscent of the mockingbird that follows me when I’m mowing the grass, picking off the insects that had been hiding there.”
Now, nearly 20 years after that first trip to Peru, Brumfield has again teamed up with Rosenberg, who is now at Cornell University’s Laboratory of Ornithology, along with Jose Tello of the American Museum of Natural History and three other LSU researchers – Matt Carling, Zac Cheviron and Nanette Crochet – to study the evolution of army-ant following.
“Over the last 50 years there has been some outstanding work on the ecology and behavior of army-ant-following birds, but the details of how the specialization evolved had not yet been examined,” Brumfield said.
The team published their findings in this month’s issue of “Molecular Phylogenetics and Evolution.”
“Using a hypothesis of the evolutionary relationships among antbird species that we reconstructed from DNA gene sequences, what we found is that army-ant following has been around a long time, possibly as long as six million years, and that its evolution followed a logical progression from least specialized to most specialized,” said Brumfield.
There are three main categories of specialization found in army-ant-following birds. The first, called occasional army-ant followers, are the most casual of the three, utilizing the insects to round up food but only as the swarm passes through their territory. Regular army-ant followers, the next level up in specialization, will follow the army ants outside of the flock’s territory but are not completely dependent on the ants to provide food. These birds regularly hunt for themselves. The final, and perhaps most interesting, category is that of the professional army-ant followers. These birds are completely reliant on the army ants for food, presenting a problem almost as unique as the situation itself.
“These birds depend almost solely on one species of army ant, called Eciton burchellii,” said Brumfield. “This makes the professional army-ant followers sensitive to many of the very real threats to this ecosystem, like deforestation, global warming and other similar issues. If anything affects the ant population, it could be devastating for these birds. But what is perhaps most surprising is that, despite the bird’s dependence on one primary ant species, the specialization has persisted for millions of years.”
12 October 2007
The switch has been thrown on a telescope specifically designed to seek out alien life. Funded by Microsoft co-founder Paul Allen the finished array will have 350 6m antennas and will be one of the world's largest. The Allen Telescope Array (ATA) will be able to sweep more than one million star systems for radio signals generated by intelligent beings. Its creators hope it will help spot definite signs of alien life by 2025.…continues at the BBC: Skies to be swept for alien life
09 October 2007
08 October 2007
….With the recent unexplained disappearance of 25 percent of the U.S. honeybee population, interest in beekeeping is at an all-time high among city dwellers, said Peter Sinton, president of the San Francisco Beekeepers' Association. Membership in the bee club has nearly doubled to 133 in the last three years, ever since apiaries began reporting cases of colony collapse disorder, shocking hive desertions that today threaten the pollination of $14 billion worth of the nation's fruit and vegetable crops. "It has caused a lot of people to worry about the bees, and think that maybe they could become a beekeeper," Sinton said. "In the ecologically oriented Bay Area, the idea strikes a nice chord."It turns out bees get by just fine in a concrete jungle. They typically forage for pollen in a 3-mile radius of the hive, and can thrive on the city's buffet of imported ornamental plants on balconies and rooftops and the dozens of community gardens that dot the city.…
…read it all in today's San Francisco Chronicle: S.F. beekeepers reap a sweet harvest
05 October 2007
04 October 2007
Eavesdropping iguanas heed hawk alarms
Galápagos iguanas may not be able to communicate amongst themselves, but it seems they can still catch the drift of mockingbird conversations. A new study shows that the island lizards – needfully wary of predators – often run to a sheltered location upon hearing alarm calls produced by mockingbirds.
02 October 2007
"They're saying we're endangering the trees when they're planning to chop them down," he said. "It's a big joke."
No joke for the trees, unfortunately, which the speaker, Zachary Running Wolf, "a former Berkeley mayoral candidate" is helping to protect from University of California Berkeley officials who want to cut down a grove of oaks to build a new sports facility.
Read it all: Get out of the trees, judge tells Cal sitters in today's San Francisco Chronicle.
01 October 2007
A variety of migrating birds, as well as bats and even hamsters successfully use a 'magnetic sense' to navigate on long journeys. Now, a new type of sensor developed by scientists in the US could make it possible for humans do the same trick.
from: Magnetic sensor could allow pigeon-style GPS in New Scientist
[Falcon by Doug Millison]