May 17, 2006, 10:16 PM CT

What Do Black Bears Eat?

Black bears may be the least carnivorous of the "carnivores" of North America. They consume a wide variety of seasonally abundant herbs, forbs, fruits, berries, nuts, and other plant parts and products. The specific plants may differ among the a number of ecoregions of North America. However, certain trends are evident. Spring foods are predominantly grasses, sedges, shoots and other high-protein lush green vegetation. Deer and other carcasses may be scavenged, as well as leftover nuts. Skunk cabbage is important in Massachusetts and squaw root in the southern Appalachians. During summer, bears shift to energy-rich "soft mast" foods such as huckleberries, blackberries, raspberries, grapes, and cherries. Protein-rich insects such as ants, wasps, and beetle larvae are usually taken.

Crayfish, frogs, birds' eggs, mice, red squirrels, woodchucks, snowshoe hare, and other animal food are occasionally eaten. Then, in autumn (where available), "hard mast" items including acorns, hickory nuts, beechnuts, hazelnuts, pine nuts, and similar foods are taken. Corn is also eaten where available. Bears can make tremendous weight gains in fall, as much as 3 to 4 lbs. per day. However, in northern areas, where hard mast is lacking, bears must rely only on berry crops for weight gain and den after those are exhausted. Bears, especially adult males, and especially when foods are scarce, may travel up to 125 miles outside their home range in late summer and early fall to a concentrated food source before returning home to den. A number of historical accounts from Louisiana, Minnesota, New England, Ontario, Wisconsin, and elsewhere mention these "migrations" or "forays", which often followed well-defined trails beaten down over time.........

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May 17, 2006, 0:04 AM CT

Chimpanzee study reveals genome variation hotspots

Scientists think that dynamic regions of the human genome -- "hotspots" in terms of duplications and deletions -- are potentially involved in the rapid evolution of morphological and behavioral characteristics that are genetically determined.

Now, an international team of researchers, including a graduate student and an associate professor from Arizona State University, are finding similar hotspots in chimpanzees, which has implications for the understanding of genomic evolution in all species.

"We found that chimpanzees have a number of copy number variants -- duplications or deletions of large segments of DNA -- in the same regions of the genome as do humans. What this suggests is that some regions of the genomes are inherently unstable in both humans and chimpanzees," says George (P.J.) Perry, a Ph.D. anthropology student working with Anne Stone, an associate professor in ASU's School of Human Evolution and Social Change in the College of Liberal Arts and Sciences.

"This is a relatively new area of research and this is the first time this has been investigated on a genome-wide scale in a population sample of nonhuman primates," Perry says of the findings published May 15 in the online early edition of the journal Proceedings of the National Academy of Sciences (PNAS).........

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May 16, 2006, 11:00 PM CT

Small Molecule Interactions Were Central To The Origin Of Life

In an important new paper forthcoming in the recent issue of The Quarterly Review of Biology, Robert Shapiro (New York University) argues against the widely held theory that the origin of life began with the spontaneous appearance of a large, replicating molecule such as RNA. Instead, Shapiro raises an alternative that does not depend on a "stupendously improbable accident," presenting the more plausible idea that life began within a mixture of simple organic molecules, multiplied through catalyzed reaction cycles and an external source of available energy.

"The diversity of organic chemistry, with its harvest of competing, interconnected reactions, becomes an asset rather than a liability in the case of the energy-driven system," explains Shapiro. "The existence of side reaction paths can provide the network with the capacity of reacting to circumstances."

Shapiro outlines how replicator theories, though they have been supported by "prebiotic" syntheses carried out by chemists using modern apparatus and purified reagents, are highly unlikely. The creation of a molecule that can self-replicate requires the combination of diverse chemicals in a long sequence of reactions in a specific order, interspersed by complicated separations, purifications, and changes in locale.........

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May 16, 2006, 0:14 AM CT

Plants Tell Caterpillars When It's Safe To Forage

The world is filled with cues that could influence the daily feeding patterns of an organism. A number of plants, for example, respond to foraging damage by releasing specialized chemical signals - volatile organic compounds that evaporate in the air - that attract the forager's natural enemies. This strategy is obviously no use against a cow, but proves effective when the offender is a caterpillar and the summoned predator is a wasp. Just how much control such biotic factors exert over a forager's daily routine has remained an open question. But in a new study in the open access journal PLoS Biology, Kaori Shiojiri, Rika Ozawa, and Junji Takabayashi show that plant signals can indeed regulate herbivore behavior.

When the larvae of beet armyworms (Spodoptera exigua) feed on corn, the plant releases volatile compounds that act as a magnet for parasitic wasps (Cotesia marginiventris), which deposit their eggs in the larvae. Production of volatile chemicals increases during the day (when wasps are active) and decreases at night, suggesting that variations in production might affect the daily activity patterns of foraging larvae, with low production sending the signal that the coast is clear. To test this hypothesis, Shiojiri et al. exposed larvae of a corn-munching nocturnal caterpillar, Mythimna separata, to volatile compounds from corn and varied the light and dark conditions for both corn and insect. Corn infested with M. separata releases volatiles that attract parasitic wasps (C. kariyai).........

Posted by: Erica      Permalink         Source

May 14, 2006, 3:52 PM CT

Female Guppies Risk Their Lives To Avoid Male Harassment

Sexual harassment is a burden that females of a number of species face, and some may go to extreme lengths to avoid it. In a new paper from the recent issue of the American Naturalist, Darren Croft (University of Wales) and a research team from the University of Leeds suggest that female guppies, a popular aquarium fish, may risk their lives to avoid too much attention from males. Observing wild population of guppies in the rainforest of Trinidad, the scientists found that female guppies swim in habitats that contain few males - but a number of predators.

"Male guppies spend most of their time displaying to females. But if their courtship displays don't impress the females, males will attempt to sneak mating with them when they aren't looking," says Croft.

Male guppies are brightly colored to attract female attention, while female guppies are a dull brown color. The scientists show that female guppies might use this color difference to their advantage, venturing into the deep water where predators lurk. The males' bright coloring also attracts predators, making it too dangerous for them to follow.

"Understanding why and how [sexual segregation] occurs is essential if we are going to conserve and protect species and habitats," explains Croft, who points out that fish are not the only species who display this social characteristic. "In a number of ecosystems, predators are the first to go extinct, and our work shows that this may have a number of, perhaps unexpected, effects. In this case, females may suffer more sexual harassment."........

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May 14, 2006, 3:43 PM CT

Tracking DNA Damage In Fish

Like coal-mine canaries, fish DNA can serve as a measure of the biological impact of water and sediment pollution--or pollution clean-up. That's one of the conclusions of a new study* by scientists from the Pacific Northwest Research Institute (PNRI), Woods Hole Oceanographic Institution, the University of Maryland and the National Institute of Standards and Technology (NIST).

Research over the past several years has demonstrated the adverse effects of industrial pollutants in water and sediment on the health of fish in the lower Duwamish River. The Duwamish flows through an industrialized section of south Seattle, Wash., and in 2001 a section of the lower river was added to the Environmental Protection Agency's Superfund list because of contaminants including polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), mercury and other metals, and phthalates. In prior research on Duwamish fish, PNRI used an infrared spectroscopy method to document DNA damage in the gills of English sole.

In a new joint paper, the scientists report on several biomarkers, including pollution-induced P450 enzyme changes, and on infrared spectral analysis of DNA and measurements of specific modifications to DNA from fish gills and livers using liquid and gas chromatography combined with mass spectrometry (LC/MS,GC/MS). Precision chemical analysis techniques at NIST allowed the scientists to identify and measure damage to adenine and guanine, specific chemical components or bases of DNA, at extraordinarily low levels--five lesions out of a 100 million bases in one case. The results correlated well with earlier research and revealed similar damage to liver DNA (more likely tied to the fish's food) and gill DNA (more probably reflecting pollutants in water).........

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May 12, 2006, 0:11 AM CT

Ray Grizzle Is Restoring Oyster Reefs

In the past decade, the oyster population in New Hampshire's Great Bay estuary has plummeted by 90 percent, due to the 1995 arrival of the oyster disease MSX. The previous century saw a slower but equally devastating demise of oysters from exuberant overharvesting. "We have seen local extinction on some reefs," says Ray Grizzle, research associate professor at the University of New Hampshire's Jackson Estuarine Laboratory.

Now Grizzle is working to bring oysters back to Great Bay - lots of them. He's helping the state of New Hampshire meet its established goal of restoring 20 acres of oyster reefs by 2010. "I hope we're going to have a bay with a healthy oyster population, and we're going to work hard to do it," he says. His research explores which are the best reef restoration techniques for the Great Bay estuarine system (www.oysters.unh.edu).

Oyster reef restoration involves providing sufficient hard substrate - typically oyster shells on which young oysters settle and grow - and seeding it with disease-resistant young oysters. Natural oyster reefs are formed by live oysters atop mounds of empty shells; one initiative of Grizzle's lab is soliciting "recycled" empty shells from oyster harvesters that will eventually be returned to the bay to provide substrate.........

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May 12, 2006, 0:01 AM CT

Scientists Discovers New Primate Genus

In January 2006, researchers from the Wildlife Conservation Society were in the forests of Tanzania searching for a grayish, tree-dwelling primate that had been identified in photographs as a new species the prior summer.

Half a world away, in a laboratory at the University of Alaska Fairbanks, Assistant Professor Link Olson and undergraduate biology major Kyndall Hildebrandt were looking at DNA test results that pointed to an even more notable finding.

The monkey wasn't just an example of a new species; it belonged to a new genus.

"A new genus in any living mammal group is noteworthy," said Olson, who also serves as the curator of mammals at the University of Alaska Museum of the North. "Finding a new genus in the best-studied group of living mammals is a sobering reminder of how much we have to learn about the planet's biodiversity."

This is the first time in 83 years that researchers have identified a new genus of living African primate. A paper detailing the discovery is slated would be reported in the journal Science on June 2, 2006 and appears today in the online edition of the journal, Science Express.

Download photoThe monkey was dubbed Rungwecebus kipunji for its home range on Mt. Rungwe in Tanzania. Researchers first described the kipunji in 2005 and noted that it differed in appearance and behavior from other known species of monkey. They first classified it in the genus Lophocebus, which includes three other species of monkeys called mangabeys. However, that classification was based only on field observations and photographs.........

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May 11, 2006, 0:25 AM CT

Wasps Queue For Top Job

Scientists at UCL (University College London) have discovered that even wasps are driven by their status. The study, published recently in Nature, shows that lower-ranked female wasps work harder to help their queen than those higher up the chain because they have less to lose, and consequently are prepared to take more risks and wear themselves out.

The study, funded by the Natural Environment Research Council (NERC), reveals that those higher up the chain and therefore with a greater chance of being the next in line to breed are much lazier than their lower-ranked nest-mates: rather than use up their energy in foraging to feed the queen's larvae, high-rankers sit tight on the nest and wait for their chance to become queen themselves.

Dr Jeremy Field, UCL Department of Biology, said: "Helpers wait peacefully in an age-based queue to inherit the prize of being the queen or breeder in the group. The oldest female almost always becomes the next breeder. The wasps in this queue face a fundamental trade-off: by working harder, they help the group as a whole and as a result indirectly benefit themselves, but they simultaneously decrease their own future survival and fecundity because helping is costly. It involves energy-expensive flight to forage for food, and leaving the nest is dangerous. We have found that the brighter the individual wasp's future, the less likely it is to take risks by leaving the safety of its nest to forage for food".........

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May 11, 2006, 0:12 AM CT

The Higher The Hierarchy, The Greater The Aggression

Individual variation in social behavior is one of the most striking features of cooperative animal societies. In a new study from the recent issue of American Naturalist, Michael A. Cant (University of Cambridge), Justine B. Llop (University of Cambridge), and Jeremy Field (University College London) investigate the extent to which differences in aggressive behavior within a cooperative society can be explained by "inheritance rank"--the likelihood that an individual will get to mate successfully in that society based on their rank--or place in the social hierarchy. They can only pass on their genes when they reach the top of the hierarchy, commonly after those ahead of them in the rank have died and they have inherited the right to reproduce.

"Certain group members inflict or receive a number of more acts of aggression than others. In some cases, these acts (which include bites, shoves, mounts, and charges) appear to regulate cooperative activity in the group by activating lazy workers, for example, or punishing defectors," write the researchers.

The scientists developed two simple mathematical models that predicted that, if inheritance rank mattered in a cooperative society, then the rates of aggression would be highest toward the front of the queue and that the aggression would increase as the time available to inherit the ability to breed ran out in seasonal animals. These predictions were tested on field colonies of the paper wasp Polistes dominulus by recording aggression between all group members and then repeatedly removing the dominant wasps.........

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