June 10, 2009, 8:50 PM CT

Evolution can occur in less than 10 years

How fast can evolution take place? In just a few years, as per a newly released study on guppies led by UC Riverside's Swanne Gordon, a graduate student in biology.

Gordon and her colleagues studied guppies small fresh-water fish biologists have studied for long from the Yarra River, Trinidad. They introduced the guppies into the nearby Damier River, in a section above a barrier waterfall that excluded all predators. The guppies and their descendents also colonized the lower portion of the stream, below the barrier waterfall, that contained natural predators.

Eight years later (less than 30 guppy generations), the scientists observed that the guppies in the low-predation environment above the barrier waterfall had adapted to their new environment by producing larger and fewer offspring with each reproductive cycle. No such adaptation was seen in the guppies that colonized the high-predation environment below the barrier waterfall.

"High-predation females invest more resources into current reproduction because a high rate of mortality, driven by predators, means these females may not get another chance to reproduce," explained Gordon, who works in the lab of David Reznick, a professor of biology. "Low-predation females, conversely, produce larger embryos because the larger babies are more competitive in the resource-limited environments typical of low-predation sites. Moreover, low-predation females produce fewer embryos not only because they have larger embryos but also because they invest fewer resources in current reproduction"......... Posted by: Kelly      Read more         Source

June 8, 2009, 10:19 PM CT

Complexity of animal mating choices

When female tiger salamanders choose a mate, it turns out that size does matter - tail size that is - and that's not the only factor they weigh.

Findings of a Purdue University study show that animals make more complex decisions about choosing mates than once thought. The results of Andrew DeWoody's study, released Monday (June 8) in the journal Molecular Ecology, refute a theory that animals use major histocompatibility complex (MHC) genes as the sole basis for mate choice. Immunologists have long known that MHC genes play key roles in the immune response, but more recently behavioral ecologists have postulated that animal mate choice is often based on MHC-type because of the function of those genes.

"Our data indicate that mate-choice decisions aren't solely dependent on MHC, tail length, body size or any other single factor," said DeWoody, a professor of genetics. "Mate choice is a complex process that takes a number of factors into account".

DeWoody and David Bos, a former postdoctoral assistant who is now a continuing lecturer at Purdue, set out to see how much MHC genes affected mate choice in wild animals. Most previous research showed that an animal would choose a mate with MHC that is the most divergent from its own so that offspring will have more effective immune systems......... Posted by: Kelly      Read more         Source

June 5, 2009, 4:57 AM CT

Bats recognize the individual voices of other bats

Bats can use the characteristics of other bats' voices to recognize each other, as per a research studyby scientists from the University of Tuebingen, Gera number of and the University of Applied Sciences in Konstanz, Gera number of. The study, published June 5 in the open-access journal PLoS Computational Biology, explains how bats use echolocation for more than just spatial knowledge.

The scientists first tested the ability of four greater mouse-eared bats to distinguish between the echolocation calls of other bats. After observing that the bats learned to discriminate the voices of other bats, they then programmed a computer model that reproduces the recognition behaviour of the bats. Analysis of the model suggests that the spectral energy distribution in the signals contains individual-specific information that allows one bat to recognize another.

Animals must recognize each other in order to engage in social behaviour. Vocal communication signals are helpful for recognizing individuals, particularly in nocturnal organisms such as bats. Little is known about how bats perform strenuous social tasks, such as remaining in a group when flying at high speeds in darkness, or avoiding interference between echolocation calls. The finding that bats can recognize other bats within their own species based on their echolocation calls may therefore have some significant implications......... Posted by: Kelly      Read more         Source

June 5, 2009, 4:50 AM CT

Corals' "Internal Communication"

Corals, it appears, have a genetic complexity that rivals that of humans, have sophisticated systems of biological communication that are being stressed by global change, and are only able to survive based on proper function of an intricate symbiotic relationship with algae that live within their bodies, say researchers in a paper published in this week's issue of the journal Science.

Disruptions in these biological and communication systems are the underlying cause of the coral bleaching and collapse of coral reef ecosystems around the world.

"We've known for some time the general functioning of corals and the problems they are facing from climate change," said Virginia Weis, a zoologist at Oregon State University.

"But until just recently, much less has been known about their fundamental biology, genome structure and internal communication. Only when we really understand how their physiology works will we know if they can adapt to climate changes, or ways we might help".

Reef-building corals are facing severe environmental threats, said Clayton Cook, program director in the National Science Foundation (NSF)'s Division of Integrative and Organismal Systems, which funded the research. "The most evident are bleaching events linked to higher ocean temperatures, and the effects of ocean acidification on reef-building......... Posted by: Janet      Read more         Source

June 5, 2009, 4:47 AM CT

Different genes cause loss of body parts

New research shows that when two species of stickleback fish evolved and lost their pelvises and body armor, the changes were caused by different genes in each species.

That surprised researchers, who expected the same genes would control the same changes in both related fish.

Results of the study, funded by the National Science Foundation (NSF)'s Divisions of Environmental Biology and Integrative Organismal Systems, are published online today in the journal Current Biology

"Earth's climate and biosphere are changing rapidly and in unpredictable ways," says Penny Firth, deputy director of NSF's Division of Environmental Biology. "A major challenge for biology is understanding the connections among evolving genomes, evolving populations and changing ecosystems. This research takes an important step by illuminating the genetic basis of evolutionary change in long-separated lineages".

Biologists knew that in a number of cases of evolution, "the same gene has been used over and over again--even in different species--to result in the same anatomy," says Mike Shapiro, first author of the paper and a biologist at the University of Utah. "What we are finding now is that different genes can have similar effects".

The findings shed new light on how evolution produces diversity in nature, and on the evolution of limb loss--and not just the loss of the pelvis and leg-like pelvic spines in certain sticklebacks......... Posted by: Kelly      Read more         Source

June 1, 2009, 7:17 PM CT

Coryphodon

Ancestors of tapirs and ancient cousins of rhinos living above the Arctic Circle 53 million years ago endured six months of darkness each year in a far milder climate than today that featured lush, swampy forests, as per a newly released study led by the University of Colorado at Boulder.

CU-Boulder Assistant Professor Jaelyn Eberle said the study shows several varieties of prehistoric mammals as heavy as 1,000 pounds each lived on what is today Ellesmere Island near Greenland on a summer diet of flowering plants, deciduous leaves and aquatic vegetation. But in winter's twilight they apparently switched over to foods like twigs, leaf litter, evergreen needles and fungi, said Eberle, curator of fossil vertebrates at the University of Colorado Museum of Natural History and chief study author.

The study has implications for the dispersal of early mammals across polar land bridges into North America and for modern mammals that likely will begin moving north if Earth's climate continues to warm. A paper on the subject co-authored by Henry Fricke of Colorado College in Colorado Springs and John Humphrey of the Colorado School of Mines in Golden appears in the recent issue of Geology

The team used an analysis of carbon and oxygen isotopes extracted from the fossil teeth of three varieties of mammals from Ellesmere Island -- a hippo-like, semi-aquatic creature known as Coryphodon, a second, smaller ancestor of today's tapirs and a third rhino-like mammal known as brontothere. Animal teeth are among the most valuable fossils in the high Arctic because they are extremely hard and better able to survive the harsh freeze-thaw cycles that occur each year, Eberle said......... Posted by: Kelly      Read more         Source

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 24, 2009, 8:53 PM CT

Thanks to spillover from landscape corridors

Recently, images of melting sea ice and shrinking rainforests have highlighted the world's biodiversity crisis and made us aware of the need to find a balance between preserving natural ecosystems while still having enough land for human use.

"About 10 percent of the world's land surface is afforded formal protection. We need to manage that 10 percent as best as we possibly can to preserve biodiversity but also be mindful of human needs, such as food and fiber production," said Lars A. Brudvig, Ph.D., post-doctoral researcher in biology in Arts & Sciences at Washington University in St. Louis.

"One way to do this is by managing the land in a way that promotes biodiversity beyond the habitat's borders."

One of the most popular ways to manage landscapes fragmented by humans is to connect the isolated patches of habitat with skinny strips of land called corridors.

Brudvig and Ellen I. Damschen, Ph.D., assistant professor of biology at Washington University, in collaboration with scientists at the University of Washington, North Carolina State University and University of Florida, have discovered that the biodiversity in a patch of habitat can extend outside the borders of a protected area; this effect is magnified when the habitats are connected by corridors......... Posted by: Erica      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 21, 2009, 6:07 AM CT

Important Role For Junk Dna

Researchers have called it "junk DNA." They have long been perplexed by these extensive strands of genetic material that dominate the genome but seem to lack specific functions. Why would nature force the genome to carry so much excess baggage?.

Now scientists from Princeton University and Indiana University who have been studying the genome of a pond organism have observed that junk DNA may not be so junky after all. They have discovered that DNA sequences from regions of what had been viewed as the "dispensable genome" are actually performing functions that are central for the organism. They have concluded that the genes spur an almost acrobatic rearrangement of the entire genome that is necessary for the organism to grow.

It all happens very quickly. Genes called transposons in the single-celled pond-dwelling organism Oxytricha produce cell proteins known as transposases. During development, the transposons appear to first influence hundreds of thousands of DNA pieces to regroup. Then, when no longer needed, the organism cleverly erases the transposases from its genetic material, paring its genome to a slim 5 percent of its original load.

"The transposons actually perform a central role for the cell," said Laura Landweber, a professor of ecology and evolutionary biology at Princeton and an author of the study. "They stitch together the genes in working form." The work appeared in the May 15 edition of Science......... Posted by: Janet      Read more         Source