May 28, 2009, 5:12 AM CT

City rats loyal to their neighborhoods

n the rat race of life, one thing is certain: there's no place like home.

Now, a study published this week in the journal Molecular Ecology finds the same is as true for rats as for humans.

Eventhough inner city rodents appear to roam freely, most form distinct neighborhoods where they spend the majority of their lives.

Like any major city, Baltimore, Md., has a number of lively neighborhoods--each with its own personality. But researchers from the Johns Hopkins University Bloomberg School of Public Health say humans aren't the only Baltimoreans loyal to their 'hoods.

Rats typically stay close to home, rarely venturing more than a city block away. In the face of danger, however, some rodents can travel as far as seven miles to repopulate abandoned areas.

An understanding of how rats in urban areas are connected provides information about which populations may spread disease, as per Sam Scheiner, program director in the National Science Foundation (NSF)'s Division of Environmental Biology, which funded the research through the joint NSF-National Institutes of Health Ecology of Infectious Diseases program.

Baltimore's port was a once major delivery point for grain, likely how Norway rats were first introduced to the city. Norway rats, also called wharf rats, sewer rats or brown rats, can weigh nearly two pounds and transmit a variety of diseases to humans......... Posted by: Kelly      Read more         Source

May 21, 2009, 6:10 AM CT

Contaminants in Marine Mammals' Brains

The most extensive study of pollutants in marine mammals' brains reveals that these animals are exposed to a hazardous cocktail of pesticides such as DDTs and PCBs, as well as emerging contaminants such as brominated flame retardants.

Eric Montie, the main author on the study currently in press and published online April 17 in Environmental Pollution, performed the research as a student in the Woods Hole Oceanographic Institution-MIT Joint Graduate Program in Oceanography and Ocean Engineering and as a postdoctoral fellow at the Woods Hole Oceanographic Institution (WHOI). The final data analysis and writing were conducted at College of Marine Science, University of South Florida, where Montie now works in David Mann's marine sensory biology lab.

Co-author Chris Reddy, an associate scientist in the WHOI Marine Chemistry and Geochemistry Department, describes the work as "groundbreaking because Eric measures a variety of different chemicals in animal tissues that had not been previously explored. It gives us greater insight into how these chemicals appears to behave in marine mammals."

The work represents a major collaborative effort between the laboratories of Reddy and Mark Hahn in the WHOI Biology Department, where Montie was a graduate student and post doc, as well as Robert Letcher at Environment Canada. Montie traveled to Environment Canada in Ottawa to learn the painstaking techniques mandatory to extract and to quantify more than 170 different pollutants and their metabolites. He then brought the methods back to WHOI and performed the analyses in Reddy's laboratory. Reddy describes the methods as extremely unforgiving and explains, "This is not making Toll House cookies. The fact that Eric pulled it off so seamlessly is amazing considering that he did this by himself far away from Ottawa"......... Posted by: Kelly      Read more         Source

May 20, 2009, 7:34 PM CT

Endangered right whales found where presumed extinct

Using a system of underwater hydrophones that can record sounds from hundreds of miles away, a team of researchers from Oregon State University and the National Oceanic and Atmospheric Administration has documented the presence of endangered North Atlantic right whales in an area they were believed to be extinct.

The discovery is especially important, scientists say, because it is in an area that appears to be opened to shipping if the melting of polar ice continues, as expected.

Results of the study were presented this week at a meeting of the Acoustical Society of America in Portland, Ore.

The researchers are unsure of exactly how a number of whales were in the region, which is off the southern tip of Greenland and site of an important 19th-century whaling area called Cape Farewell Ground. But they recorded more than 2,000 right whale vocalizations in the region from July through December of 2007.

"The technology has enabled us to identify an important unstudied habitat for endangered right whales and raises the possibility that contrary to general belief a remnant of a central or eastern Atlantic stock of right whales still exists and might be viable," said David Mellinger, an assistant professor at OSU's Hatfield Marine Science Center in Newport and chief scientist of the project......... Posted by: Kelly      Read more         Source

May 20, 2009, 7:30 PM CT

Green fluorescent proteins in marine creature

Scientists at Scripps Institution of Oceanography at UC San Diego and the Salk Institute for Biological Studies have discovered a family of green fluorescent proteins (GFPs) in a primitive sea animal, along with new clues about the role of the proteins that has nothing to do with their famous glow.

GFPs recently gained international attention with the awarding of the 2008 Nobel Prize in Chemistry, shared by UC San Diego's Roger Tsien, as word spread of their extensive presence in nature as well as benefit to researchers. GFPs, originally isolated from a luminous jellyfish, have gained scientific ubiquity in uses ranging from biomedical tracers to probes for testing environmental quality. But while the value of GFPs in biomedicine and bioengineering has become evident, their diversity across the tree of life and their role in nature haven't been as easily deciphered.

New hints have emerged as Erin Bomati, a former postdoctoral researcher at Scripps Oceanography, Gerard Manning of the Salk Institute for Biological Studies and Scripps lead-scientist Dimitri Deheyn discovered the largest known family of GFPs. They found 16 related types of GFPs in amphioxus, a thin, non-luminous fish-like animal that lives in coastal areas and spends most of its time burrowed in ocean sand. The discovery, described in the journal BioMed Central (BMC) Evolutionary Biology, was made in Branchiostoma floridae, an amphioxus species collected off Tampa, Fla......... Posted by: Kelly      Read more         Source

May 20, 2009, 6:51 PM CT

Bird songs change with the landscape

When the going gets rough, the tough apparently sing slower.

As vegetation reclaimed formerly cleared land in California, Oregon and Washington over the last 35 years, male white-crowned sparrows have lowered their pitch and slowed down their singing so that their love songs would carry better through heavier foliage.

"This is the first time that anyone has shown that bird songs can shift with rapid changes in habitat," says biologist Elizabeth Derryberry who made the finding as part of her dissertation research at Duke University.

She compared recordings of individual birds in 15 different areas with some nearly forgotten recordings made at the same spots in the 1970s by a California Academy of Sciences researcher, and observed that the musical pitch and speed of the trill portion of the sparrows' short songs had dropped considerably. "I was really surprised to find that songs had changed in a similar way in so a number of different populations".

She then used archival aerial photography to see how the foliage had changed in a subset of those spots, and observed that the one population whose song hadn't slowed down lived in an area where the foliage hadn't changed either.

The physics is clear, but the biology is a little less certain. A lower, slower song suffers less reverberation in denser foliage and will be heard more accurately. In turn, that means it is more likely to be copied by young males who are choosing which song they will learn. Over generations, that should cause the song to slow down and drop in pitch as the foliage changes......... Posted by: Kelly      Read more         Source

May 20, 2009, 6:49 PM CT

Snail venoms reflect reduced competition

A study of venomous snails on remote Pacific islands reveals genetic underpinnings of an ecological phenomenon that has fascinated researchers since Darwin.

The research, by University of Michigan evolutionary biologists Tom Duda and Taehwan Lee, is scheduled to be published online May 20 in the open-access journal PLoS ONE

In the study, Duda and Lee explored ecological release, a phenomenon believed to be responsible for some of the most dramatic diversifications of living things in Earth's history. Ecological release occurs when a population is freed from the burden of competition, either because its competitors become extinct or because it colonizes a new area where few or no competitors are found. When this happens, the "released" population typically expands its diet or habitat, taking over resources that would be off-limits if competitors were present. This expansion is believed to drive the evolution of adaptations for taking advantage of the new resources, such as venoms tailored to a broader array of prey.

"Eventhough there are plenty of examples of populations expanding into a variety of niches after experiencing ecological release, little is known about the evolution of genes linked to this phenomenon," said Duda, an assistant professor in the U-M Department of Ecology and Evolutionary Biology......... Posted by: Kelly      Read more         Source

May 20, 2009, 6:27 PM CT

Small evolutionary shifts make big impacts

In the developing fetus, cell growth follows a very specific schedule. In the eye's retina, for example, cones -- which help distinguish color during the day -- develop before the more light-sensitive rods -- which are needed for night vision.

But minor differences in the timing of cell proliferation can explain the large differences found in the eyes of two species -- owl monkeys and capuchin monkeys -- that evolved from a common ancestor.

Scientists from Cornell, St. Jude's Children's Research Hospital in Tennessee and the Federal University of Para, Brazil, have found an evolutionary mechanism that provides insight into how important changes in brain structure of primates can evolve.

That evolution appears to proceed via simple genetic changes that affect the timing of development of brain regions, they report in a paper published May 18 online and in a future print issue of Proceedings of the National Academy of Sciences.

In both monkey species, the specialized eye cells develop in the growing embryo from a single retinal progenitor cell. In their basic design, the eyes of these primates have the capability and necessary architecture to be either nocturnal or diurnal, based on a species' ecological niche and needs, said Cornell neurobiologist and psychology expert Barbara Finlay......... Posted by: Kelly      Read more         Source

May 19, 2009, 5:11 AM CT

New insight into primate eye evolution

Scientists comparing the fetal development of the eye of the owl monkey with that of the capuchin monkey have observed that only a minor difference in the timing of cell proliferation can explain the multiple anatomical differences in the two kinds of eyes.

The findings help researchers understand how a structure as complex as the eye could change gradually through evolution, yet remain functional. The findings also offer a lesson in how seemingly simple genetic changes in the brain and nervous system could produce the multiple evolutionary changes seen in more advanced brains, without compromising function.

Analysis for this study waccording toformed at St. Jude Children's Research Hospital. The primates were housed at the Centro Nacional de Primates in Brazil. Contributing scientists at Cornell University and Universidade Federal do Par, Brazil, approved all procedures. The scientists published their findings in the early online issue of Proceedings of the National Academy of Sciences

"The molecular, cellular and genetic pathways that coordinate proliferation during development have been fine-tuned since the first multicellular organisms emerged millions of years ago," said Michael Dyer, Ph.D., member of St. Jude Developmental Neurobiology and the paper's first author. "When these pathways are deregulated during human development, one of the consequences is childhood cancer. Therefore, by studying how changes in the regulation of proliferation during development can lead to dramatic changes in form and function during evolution, we can gain a deeper understanding of these ancient pathways that lie at the heart of a number of pediatric cancers"......... Posted by: Kelly      Read more         Source

May 18, 2009, 5:32 AM CT

World's largest leatherback turtle population

An international team of researchers has identified a nesting population of leatherback sea turtles in Gabon, West Africa as the world's largest. The research, reported in the recent issue of Biological Conservation, involved country-wide land and aerial surveys that estimated a population of between 15,730 and 41,373 female turtles using the nesting beaches. The study highlights the importance of conservation work to manage key sites and protected areas in Gabon.

Leatherbacks are of profound conservation concern around the world after populations in the Indo-Pacific crashed by more than 90 percent in the 1980s and 1990s. The International Union for Conservation of Nature (IUCN) lists leatherback turtles as critically endangered globally, but detailed population evaluations in much of the Atlantic, particularly Africa, are lacking.

The research was led by the University of Exeter working in collaboration with the Wildlife Conservation Society (WCS) which spearheads the Gabon Sea Turtle Partnership, a network of organisations concerned with the protection of marine turtles in Gabon.

During three nesting seasons between 2002 and 2007, the team's members carried out the most comprehensive survey of marine turtles ever conducted in Gabon. This involved aerial surveys along Gabon's 600 km (372 mile) coast, using video to capture footage for assessment, and detailed ground-based monitoring. By covering the entire coastline, they were not only able to estimate the number of nests and nesting females, but also to identify the key sites for leatherback nesting, data which are crucial to developing conservation management plans for the species. Leatherbacks were first described nesting in Gabon in 1984......... Posted by: Kelly      Read more         Source

May 13, 2009, 5:25 AM CT

Predators ignore peculiar prey

Rare traits persist in a population because predators detect common forms of prey more easily. Scientists writing in the open access journal BMC Ecology observed that birds will target salamanders that look like the majority even reversing their behavior in response to alterations in the ratio of a distinguishing trait.

Benjamin Fitzpatrick, from the University of Tennessee, worked with Kim Shook and Reuben Izally to study the effects of the prevalence of a dorsal stripe among a group of model salamanders on the foraging behavior of a flock of Blue Jays. He said, "Maintenance of variation is a classic paradox in evolution because both selection and drift tend to remove variation from populations. If one form has an advantage, such as being harder to spot, it should replace all others. Likewise, random drift alone will eventually result in loss of all but one form when there are no fitness differences. There must therefore be some advantage that allows unusual traits to persist".

The authors placed a selection of food-bearing model salamanders into a field for six days, with striped models outnumbering the unstriped by nine to one, or vice versa. On test days, the numbers were evened out. In each case, Blue Jays were more likely to attack the models that had been most prevalent over the prior six-day period. As per Fitzpatrick, "We think that the different color forms represent different ways of blending in on the forest floor. Looking for something cryptic takes both concentration and practice. Predators concentrating on finding striped salamanders might not notice unstriped ones"......... Posted by: Kelly      Read more         Source