November 7, 2006, 10:36 PM CT

Two Nerve Cells in Direct Contact

For the first time, researchers at the Max Planck Institute for Neurobiology in Martinsried near Munich have been able to show how two nerve cells communicate with each other from different hemispheres in the visual centre. This astoundingly simple circuit diagram could at a later date provide a model for algorithms to be deployed in technical systems (Nature Neuroscience).

Movements in space create in humans and animals so-called optical flow fields which are characteristic for the movement in question. In a forward movement, the objects flow by laterally, objects at the front increase in size and objects further away hardly change at all. At a higher level in the visual centre in the brain, there must be a computation of the visual information, so that animals can differentiate between their own movement and movement of their environment and are able to correct their course if necessary. It is important for the analysis of flow fields that the movement information from both eyes is merged so that the whole flow field can be assessed. In their current study, Karl Farrow, Jürgen Haag and Alexander Borst have for the first time proved the direct link between two nerve cells, one in each half of the brain, combining the movement signals from both the facetted eyes of a fly.........

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November 7, 2006, 10:05 PM CT

Spectacular dinosaur skull comes back to Alberta

A "spectacular beast" is coming back to its original stomping grounds and making a new home at the University of Alberta--a coup that will allow its scientists to study the rare dinosaur skull up close.

"This is a very dramatic beast," said Dr. Michael Caldwell, a palaeontolgist who was instrumental in getting the skull to the U of A. "What we will have is a cast, but the specimen is one of a kind in the world. This is the last cast from the original mould and when you have a research quality cast where it is duplicated right down to a freckle, it doesn't get any better than that".

The fossils from this large herbivorous dinosaur were first found by the Sternberg family, who were hired by the Geological Survey of Canada to compete with Americans coming to Alberta to collect fossils. The Sternbergs gathered all kinds of bones, including the skull of Styracosaurus albertensis. "The specimen waccording tofect," says Caldwell. "And it's a big one--the skull is two metres long".

Styracosaurus had six long horns extending from its neck frill, a smaller horn above each of its eyes and a single horn protruding from its nose. It was a large dinosaur that could reach lengths of five metres and weigh as much as three tonnes. For almost a century, the original skull of Styracosaurus albertensis has been at the Canadian Museum of Nature in Ottawa. Now a cast of that specimen is on its way to Edmonton in a huge wooden crate on the back of a flatbed truck.........

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November 7, 2006, 4:31 AM CT

Cambodia moves to protect endangered bird

In an effort to protect a large grassland bird from possible extinction, the government of Cambodia has recently moved to set aside more than one hundred square miles of habitat for the Bengal florican, a bird now classified as endangered, as per the Wildlife Conservation Society (WCS).

The Bengal florican--a type of bustard--is restricted to tiny fragments of grassland scattered across Cambodia, Vietnam, Nepal and India, which are threatened by land conversion for industrial-scale agriculture. The new network of protected areas covers more than 100 square miles near Cambodia's Tonle Sap lake, home to what is believed to be the world's largest remaining population of floricans. Protecting grasslands is also crucial for local human communities, who in turn help to maintain the quality of the habitat through traditional grazing, burning and scrub-clearance.

The decision to protect the bird's habitat was made by Nam Tum, the provincial governor of Cambodia's Kampong Thom province, some 80 miles from the country's capital city Phnom Penh.

"We applaud the governor for taking this action to protect one of Cambodia's endangered bird species," said WCS Country Director Joe Walston of the organization's Cambodia Program. "This population of Bengal floricans represents the best hope for the entire species, so setting aside critical habitat will give the bird a fighting chance".........

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November 2, 2006, 5:13 AM CT

You Can't Judge Biodiversity By Its Bird

The canary in the coal mine, the supposed harbinger of threat for all those around it, isn't as true as it seemed for biodiversity conservation, as per a sweeping study in which a Michigan State University ornithologist participated.

A global group of researchers including Pamela Rasmussen, of the Department of Zoology, has done the most detailed study yet of how rare and threatened species of birds, mammals and amphibians are distributed across the globe. The paper, "Global Distribution and Conservation of Rare and Threatened Vertebrates," led by Ian Owens, Imperial College London, and John Gittleman, University of Virginia, is reported in the Nov. 2 edition of the British science journal Nature.

Rasmussen, an internationally renowned expert on birds and author of a recent two-volume guide to birds of South Asia, contributed species occurrence data from her vast database to the study.

What they've learned is that contrary to popular belief, pinpointing geographic areas in which species of birds are rare or endangered is not a reliable way to assume where other species of animals occur that may also be in peril.

"Birds cannot be used as predictors of rare species of mammals or amphibians," Rasmussen said. "It had been assumed on limited studies that birds could be used to determine what were priority areas of conservation for other groups. This study shows that is not the case."........

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November 1, 2006, 8:30 PM CT

Genes, Brain Chemicals And Complex Bee Behavior

Using a new combination of techniques, U.S. and European researchers have identified 36 genes that encode brain chemicals likely to play a role in the complex behaviors of the honey bee--from working in and defending the hive to foraging, displaying and interpreting dance language. Understanding the jobs these chemicals, called neuropeptides, carry out in the honey bee will help scientists understand what they do in humans, the researchers said.

Some 10,157 genes have so far been identified in the recently sequenced honey bee (Apis mellifera) genome. Jonathan Sweedler at the University of Illinois at Urbana-Champagne and his colleagues in Belgium report in the Oct. 27, 2006, issue of the journal Science they identified 36 honey bee genes that encode 100 neuropeptides. The insect's brain contains 1 million neurons--several of the organs would fit on the head of a pin--which are bathed in neuropeptides that influence the animal's vast array of behaviors.

The group used a new combination of methods that included genetic analysis, powerful computing programs and mass spectrometry to make the discoveries. Determining the gene that encodes a neuropeptide, which is a smallish protein, is harder than in most instances because the protein molecules are often so dramatically modified they no longer show any relationship to their "parent" gene.........

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November 1, 2006, 5:26 PM CT

Why There Are More Species In The Tropics?

Why are there more species in the tropics than in the temperate regions of the globe? Many of the world's species live in the tropics (perhaps more than half), but the reason has been debated for more than 100 years.

Many researchers have hypothesized that climatic factors somehow cause species to originate more quickly in tropical regions. In a paper appearing in the recent issue of The American Naturalist, John Wiens and a group of researchers from Stony Brook University have shown that, contrary to expectations, species seem to evolve at similar rates in tropical and temperate regions. What causes the difference in species numbers between tropical and temperate regions is not something special about the tropics that leads to more rapid speciation, but rather that the temperate areas were colonized more recently, leaving less time for species to originate and accumulate in these regions.

The researchers studied the causes of high tropical species richness in treefrogs in the Americas. Combining analyses of evolutionary trees based on DNA sequences with GIS-based methods for analyzing the effects of climate on species distributions, the researchers found no relationship between how quickly species originate within a group and whether that group is tropical or temperate.........

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November 1, 2006, 4:47 PM CT

Why Wolves Not Dispersing As Fast As Expected

In 1995, 14 wolves were transferred to Yellowstone National Park in the U.S. from the Canadian Rocky Mountains, with 17 more joining them the following year. More than 1,000 healthy wolves have descended from the original 31, with about 150 of them still residing in the park boundaries.

However, wolves have been known to disperse at a rate of 100 km a year, but the Yellowstone wolves have only spread at one-tenth that rate. The slow dispersal rate had stumped researchers across North America until a team of mathematical biologists at the University of Alberta recently solved the puzzle.

"When the wolves traveled far distances in their new environment it was easy for them to lose track of their mates, and the further they traveled the less likely it is for them to find a mate," said Dr. Mark Lewis, director of the U of A Centre for Mathematical Biology and a co-author of the study.

"We've shown that a reduced probability of finding mates at low densities slows the predicted rate of recolonization," added Amy Hurford, a former U of A biological sciences master's student and co-author of the study.

By the 1970s, wolves had been systematically hunted to extinction in the lower 48 states in order to protect livestock. But wolves were a keystone species in the area (i.e. they are predators and nobody preys upon them), and, after 30 years of extinction, researchers felt a reintroduction of the species would balance the burgeoning population of other animals in the area, such as elk and cougars.........

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November 1, 2006, 4:08 PM CT

Floating Lovers Count Too

In a paper from the recent issue of The American Naturalist, Vincenzo Penteriani, Fermín Otalora, and Miguel Ferrer, scientists at the Estacion Biologica de Doñana (Consejo Superior de Investigaciones Científicas, Spain), focus on the forgotten and invisible side of animal populations - the floaters. Floaters are dispersed individuals who enter the reproductive population when breeding territory or a potential mate become available.

The researchers' work has shown that factors affecting the survival of floaters within their settlement areas may directly influence the dynamics of the whole population. Vincenzo Penteriani, Fermín Otalora, and Miguel Ferrer looked at population data for the Spanish imperial eagle Aquila adalberti over the last century. With less than 150 pairs in the whole Iberian Peninsula, this eagle is one of the most threatened raptors in the world. They observed that extremely high mortalities of floaters in settlement areas cause a decrease in the number of breeders, due to the increasing difficulty of breeding pair formation and, consequently, a positive density-fecundity relationship in the breeding portion of the population.

The results support the novel idea that taking floater dynamics within settlement areas into consideration can illuminate inexplicable positive density-dependent patterns in breeding populations. "Population studies that ignore floater dynamics may fail to understand all the different factors influencing density-dependent population patterns," Penteriani says. He continues, "Clearly defining the portion of the population that shapes density-dependent patterns may help to solve some of the ambiguities that, after some seventy years of debate, still surround density-dependence and population dynamics in general".........

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November 1, 2006, 3:51 PM CT

Missing Link In Elephant Lineage

A pig-sized, tusked creature that roamed the earth some 27 million years ago represents a missing link between the oldest known relatives of elephants and the more recent group from which modern elephants descended, an international team that includes University of Michigan paleontologist William J. Sanders has found.

The group's findings, to be published this week in the Proceedings of the National Academy of Sciences, suggest that mastodons and the ancestors of elephants originated in Africa, in contrast to mammals such as rhinos, giraffes and antelopes, which had their origins in Europe and Asia and migrated into Africa. The dating of the new fossil, discovered in the East African country of Eritrea, also pushes the origins of elephants and mastodons five million years farther into the past than previous records, Sanders said.

From 35 to 25 million years ago, representatives of the group known as proboscideans (which includes elephants, mastodons and their close relatives) lived only in Africa and Arabia, and most of them were palaeomastodonts. These animals were shorter and smaller than today's elephants, with short trunks and tusks and simple teeth that were all in place at the same time, as human adult teeth are.

After 25 million years ago, larger proboscideans such as mastodons and gomphotheres-the ancestors of modern elephants-dominated the scene. Elephant-sized, with long tusks and trunks, these advanced proboscidans had more complex teeth that emerged more slowly, so that each quadrant of the mouth had only one or two functional teeth in place at a time.........

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October 31, 2006, 9:24 PM CT

Save Threatened Turtles

Ecology and conservation experts from the University of Exeter today urge international governments to work together to protect threatened Caribbean sea turtle populations.

The Cayman Islands, a UK Overseas Territory, once supported one of the world's largest sea turtle rookeries, which comprised some 6.5 million adult green and loggerhead turtles. These populations were driven into decline from the mid-1600s onwards, when massive harvesting of nesting turtles began. Only a few dozen individuals survive today.

New research, led by the University of Exeter's School of Biosciences and the Cayman Islands Department of Environment, reveals the astonishing distances these animals travel and the extent to which they are now threatened. The study was published open access today in the international conservation journal Endangered Species Research.

Marine turtles spend most of their lives at sea, but where these Cayman Islands survivors live when they are not nesting has been a mystery until now. Experts from the University of Exeter, the Cayman Islands Department of Environment and Duke University, USA, followed the journeys of ten endangered adult females over three years.

Using satellite transmitters, the team tracked the turtles travelling as far as Belize, Guatemala, Honduras, Mexico, Nicaragua and the USA. On these long journeys, turtles face the risk of being caught for meat, as well as accidentally captured by shrimp trawls, longlines, and gillnets. As turtles travel across boundaries between countries, conservation legislation is inconsistently applied and enforced, leaving them vulnerable.........

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