September 29, 2010, 11:10 PM CT

Species Accumulate on Earth at Slower Rates

Computational biologists at the University of Pennsylvania say that species are still accumulating on Earth but at a slower rate than in the past.

In the study, reported in the journal PLoS Biology, Penn scientists developed a novel computational approach to infer the dynamics of species diversification using the family trees of present-day species. Using nine patterns of diversification as alternative models, they examined 289 phylogenies, or evolutionary trees, representing amphibians, arthropods, birds, mammals, mollusks and flowering plants.

The study demonstrated that diversity is generally not at equilibrium. Nonetheless, speciation rates have typically decayed over time, suggesting that the diversification of species is somehow constrained, and that equilibrium may eventually be reached.

There are a number of competing theories for how species diversify and become extinct. Some suggest that species continually accumulate in time, always finding new ecological niches. Other theories suggest that the number of coexisting species is limited and that we will eventually have equilibrium. In other words, a species will be born only when another goes extinct.

The question that intrigued the Penn scientists was whether species diversity on Earth is in equilibrium or is still expanding. They also wondered whether the world has an invisible stop sign on species diversity that would eventually limit the diversity on the planet......... Posted by: Erica      Read more         Source

September 25, 2010, 9:38 AM CT

Adapting to Darkness

University of Maryland biologists have identified how changes in both behavior and genetics led to the evolution of the Mexican blind cavefish (Astyanax mexicanus) from its sighted, surface-dwelling ancestor. In research reported in the August 12, 2010 online edition of the journal Current Biology, Professor William R. Jeffery, together with postdoctoral associates Masato Yoshizawa, and Špela Goricki, and Assistant Professor Daphne Soares in the Department of Biology, provide new information that shows how behavioral and genetic traits coevolved to compensate for the loss of vision in cavefish and to help them find food in darkness. This is the first time that a clear link has been identified between behavior, genetics, and evolution in Mexican blind cavefish, which are considered an excellent model for studying evolution.

Why Study Blind Cavefish.

Worldwide, about 80 different species of cave-dwelling fish have evolved from surface-dwelling fish, but in most cases the surface-dwelling ancestor has disappeared. "The Mexican blind cavefish is one of the only cases where a similar ancestor still exists," explains Professor Jeffery. "Except for the loss of eyes and pigment seen in the cave-dwelling form, the surface and cave-dwellers are hard to tell apart. You can study evolution very nicely if you have both the ancestral and derived forms of evolving animals."........ Posted by: Kelly      Read more         Source

September 25, 2010, 9:33 AM CT

Analysis of the Chocolate Genome

The sequencing and analysis of the genome for the Criollo variety of the cacao tree, generally considered to produce the world's finest chocolate, was completed by an international team led by Claire Lanaud of CIRAD in France, with Mark Guiltinan of Penn State University, along with researchers from 18 other institutions. "The large amount of information generated by this project dramatically changes the status of this tropical plant and its potential interest for the scientific community," said Guiltinan, professor of plant molecular biology.

The scientists not only sequenced the genome of this ancient plant, but assembled 76 percent of the genome linking 82 percent of those genes to the 10 cacao chromosomes. This analysis identified a variety of gene families that may have future impact on improving cacao trees and fruit either by enhancing their attributes or providing protection from fungal diseases and insects that effect cacao trees.

"Relics of the ancestral Criollo first cultivated by Olmec or Maya people can still be encountered in old Mesoamerican plantations or in forests where the Maya live," said Siela Maximova, associate professor of horticulture and a member of the research team. "Our genome sequence is derived form a Belizean Criollo plant collected in the Mayan mountains"......... Posted by: Erica      Read more         Source

September 25, 2010, 9:15 AM CT

Hidden insecticide resistance

A new technique pioneered at Liverpool School of Tropical Medicine (LSTM) is improving the detection and monitoring of insecticide resistance in field populations of an important malaria-carrying mosquito.

Scientists at LSTM, led by Dr Charles Wondji have developed a new technique which encourages the female Anopheles funestus mosquitoes to lay eggs which are then reared into adult mosquitoes to provide sufficient numbers to determine levels of insecticide resistance and to characterise the underlying mechanisms.

Explaining the significance, John Morgan, who designed the technique, said: "Malaria is the main cause of death in Uganda with some 12 million cases recorded annually. The Ministry of Health relies heavily on insecticide treated nets and spraying to control mosquitoes. The effectiveness of those control programmes depends on the ability to detect and monitor insecticide resistance.

"The An.funestus mosquito is difficult to collect and rear from the field and hence published studies of insecticide resistance in this species are limited. This new forced egg laying technique encourages the females to lay eggs which we were then able to rear into viable populations.

"This allowed us to study levels of resistance to particular insecticides and in doing so, we have been able to find the first documented resistance to pyrethroid/DDT insecticides in East Africa. This will enable scientists to map the distribution of this resistance and allow the Ministry of Health to modify its vector control programme, thereby increasing its effectiveness and helping to reduce the transmission of malaria"......... Posted by: Kelly      Read more         Source

September 25, 2010, 8:51 AM CT

Cilia Revolution

University of Southern Mississippi researchers recently imitated Mother Nature by developing, for the first time, a new, skinny-molecule-based material that resembles cilia, the tiny, hair-like structures through which organisms derive smell, vision, hearing and fluid flow.

While the new material isn't exactly like cilia, it responds to thermal, chemical, and electromagnetic stimulation, allowing scientists to control it and opening unlimited possibilities for future use.

This finding is published in today's edition of the journal Advanced Functional Materials. The National Science Foundation's Division of Materials Research supports Southern Miss's Materials Research Science and Engineering Center for Response-Driven Polymeric Materials, where the research took place.

Cilia are wavy, hair-like structures that extend outward from the surfaces of various organisms such as human skin. People, animals and single-celled organisms use them to sense the environment, gather information about it and adapt to it.

Researchers long imagined what could be done if they could engineer cilia for other organic and nonorganic uses. But creating them solely belonged to the life nurturing processes of nature, until now. Marek Urban, Southern Miss professor of polymer science and engineering, along with a team of researchers, developed a new thin copolymer film with whisker-like formations that mimics Mother Nature......... Posted by: Janet      Read more         Source

September 25, 2010, 8:28 AM CT

Withering well can improve fertility

Contrary to a thousand face cream adverts, the secret of fertility might not be eternal youth. Research by the ecologist Dr. Carlos Herrera, a Professor of Research at the Consejo Superior de Investigaciones Cientficas in Seville, Spain has shown that the withering action of flowers may have evolved to protect their seeds. His research is reported in the October 2010 issue of the Annals of Botany (http://dx.doi.org/10.1093/aob/mcq160).

Prof. Herrera said: "No one has paid much attention to the corollas, collections of petals on a flower, when they shrivel. Their job is done, so it's no surprise they die. But if their job is done, why don't the petals simply drop off the plant? I thought there might be an advantage that kept the old corollas on the plant".

To test his idea, Herrera conducted a very simple experiment. He removed dead petals from some lavender. Then he observed what happened to the seeds.

Prof. Herrera said: "The results for the lavender were striking. Normally you'd expect around 60% of the lavender fruits to ripen. Without the withered petals around the fruit, only 40% ripened. The dead petals seem to have formed a protective barrier around the fruit. In this case the barrier helps prevent attack by gnat larvae who like to feed on lavender seeds"......... Posted by: Erica      Read more         Source

September 25, 2010, 7:55 AM CT

First Cultivated Ohelo Berry for Hawaii

The first cultivar of 'Ōhelo berry, a popular native Hawaiian fruit, has been released by U.S. Department of Agriculture (USDA) researchers and their university and industry cooperators.

'Ōhelo (Vaccinium reticulatum Smith) is a small, native Hawaiian shrub in the cranberry family, usually found at high elevations on the islands of Maui and Hawaii. As people scour the landscape to harvest this delectable berry for use in jam, jelly and pie filling, they unfortunately disrupt the fragile habitats where this plant grows.

In an effort to reduce damage to the environment and meet consumer demands, horticulturist Francis T.P. Zee, with the USDA Agricultural Research Service (ARS) Pacific Basin Agricultural Research Center (PBARC) in Hilo, Hawaii, is evaluating 'Ōhelo for small farm production and ornamental use. Zee collaborated with fellow ARS researchers and cooperators at the University of Hawaii at Manoa, Big Island Candies and the Big Island Association of Nurserymen. ARS is the principal intramural scientific research agency of USDA.

Zee and his team selected the offspring of seed-grown plants to create the new cultivar "Kilauea" for berry production. They found 'Ōhelo's tiny seeds readily germinated under 20-30 percent shade in well-watered and well-drained potting mixture. Plant hardiness and vigor improved with age, and some seedlings flowered just 10 months after germination, much sooner than the 5 years reported in prior studies. The 16-month-old plants Zee successfully transplanted from the greenhouse to the field produced berries a year later......... Posted by: Erica      Read more         Source

September 23, 2010, 7:26 AM CT

China tops world fish

China leads the world in tonnage of fish caught annually as well as the amount of fish consumed, as per new findings reported in National Geographic magazine.

This research, which was conducted by the University of British Columbia in collaboration with the National Geographic Society and The Pew Charitable Trusts, ranks the top 20 nations that have the greatest impact on ocean ecosystems through catching or consuming marine wildlife.

China's top ranking results from its enormous population, despite its very low per capita footprint of fish catch and consumption. Japan is high on the list too, a result of its rate of consumption (often by importation) of fish rather than its catch. The "top 20" lists of fish catch and consumption are unveiled in the recent issue of National Geographic magazine.

The United States comes in third in both lists, due to its relatively large population and tendency to eat top predator fish such as Atlantic salmon. Peru ranks second in the world in catch though is not in the top 20 fish-consuming countries because Peruvians on the whole eat little seafood.

The data come from the SeafoodPrint study, led by Daniel Pauly of the University of British Columbia and National Geographic Ocean Fellow Enric Sala.

In assessing the true impact nations have on the seas, the team needed to look not just at what a given nation caught but also at what the citizens of that nation ate. Standard methods of measuring nations' impact on the sea are misleading because, as Pauly says, "every fish is different. A pound of tuna represents roughly a hundred times the footprint of a pound of sardines"......... Posted by: Kelly      Read more         Source

September 23, 2010, 6:50 AM CT

New species of sea slug discovered

Sometimes, treasures can be found in your own backyard particularly if you know what to look for. This is what happened to Jeff Goddard, project scientist with the Marine Science Institute at UC Santa Barbara.

Goddard was working in the tide pools at Carpinteria Reef, in Carpinteria State Park, Calif., when he found a new species of nudibranch a group of sea slugs noted for their bright colors and delicate forms. Recognizing it as new, Goddard carefully documented the living specimen before preserving it and sending it off to Terrence M. Gosliner, an authority on the taxonomy of sea slugs at the California Academy of Sciences in San Francisco. Goddard kept the slug in his lab for a few days, until it laid an egg mass, and was also able to observe its early development and hatching larvae.

Gosliner named the new sea slug after Goddard when he described it and one other newly discovered species of California nudibranch in the Sept. 15 online edition of the Proceedings of the California Academy of Sciences

"The shallow-water nudibranch fauna of Southern California particularly is well known, so it was pretty exciting to find a new species right under our noses here in Santa Barbara County," said Goddard. "Only one specimen was found, so now we need to find out where more are hiding, what they feed on, and whom they interact with"......... Posted by: Janet      Read more         Source

September 9, 2010, 6:52 AM CT

First discovery of bilirubin in a flower

A research team led by Cary Pirone from the Department of Biological Sciences at Florida International University has identified bilirubin in the popular Bird of Paradise plant. The breakthrough study, reported in the September 2010 issue of the American Society for Horticultural Science's journal HortScience, provides new insights into color production in this iconic tropical plant.

Previously believed to be an "animal-only" pigment, bilirubin is best known as the yellowish hue linked to bruises and jaundice sufferers. In 2009 the FIU scientists found bilirubin in the arils of Strelitzia nicolai, the white Bird of Paradise tree. The incredible discoverythat bilirubin exists in both plants and animalsput Pirone's research on the scientific map. The current study expands the original research and reveals new insights into the presence of animal pigment in flowers. Advisor David Lee credits Pirone for her persistence and scientific acumen. "Cary has made a remarkable discovery", he noted, adding that it was Pirone's persistence and curiosity that persuaded colleagues that she was on the right track.

Strelitzia reginae Aiton, the Bird of Paradise plant, is known for its vibrant orange and blue inflorescences. Native to South Africa, it is widely cultivated in warm temperate and tropical regions. Aside from the widely recognized shape of its flower, which resembles the head of a bird, Strelitzia reginae is also admired for its brilliant floral coloration. In contrast to its showy flowers, the fruit of the Bird of Paradise is pale and partially obscured by the bract during development. When it matures, however, the capsule breaks open to reveal intensely colored orange arillate seeds. Remarkably, the distinct aril color can remain unchanged for decades after the plant dies......... Posted by: Erica      Read more         Source