How Our Ancestors Were Like Gorillas

Source:

http://www.sciencedaily.com/releases/2007/11/071129143817.htm

ScienceDaily (Nov. 30, 2007) — New research shows that some of our closest extinct relatives had more in common with gorillas than previously thought. Dr Charles Lockwood, UCL Department of Anthropology and lead author of the study, said: "When we examined fossils from 1.5 to 2 million years ago we found that in one of our close relatives the males continued to grow well into adulthood, just as they do in gorillas. This resulted in a much bigger size difference between males and females than we see today.

"It's common knowledge that boys mature later than girls, but in humans the difference is actually much less marked than in some other primates. Male gorillas continue to grow long after their wisdom teeth have come through, and they don't reach what is referred to as dominant "silverback" status until many years after the females have already started to have offspring. Our research makes us think that, in this fossil species, one older male was probably dominant in a troop of females. This situation was risky for the males and they suffered high rates of predation as a result of both their social structure and pattern of growth."
The research used 35 fossilised specimens of Paranthropus robustus, an extinct relative of Homo sapiens which existed almost two million years ago. The fossils came from the palaeontological sites of Swartkrans, Drimolen and Kromdraii, all of which are in South Africa's Cradle of Humankind World Heritage Site near Johannesburg.
The research was inspired by earlier discoveries at Drimolen by Dr Andre Keyser, one of the co-authors of the study. Dr Colin Menter, from the University of Johannesburg and co-director of current fieldwork at Drimolen, explains: "Discoveries at this site showed us that sex differences in Paranthropus robustus were greater than we had previously thought. While there are some specimens from Drimolen that are just as large and robust as those from other sites like Swartkrans, there is a complete female skull that is distinctly smaller than the other, well-preserved specimens of the species."
Jacopo Moggi-Cecchi, based at the University of Florence and an expert on fossil teeth, participated in the study and says: "It takes large samples of fossils to ask questions about variation and growth, and it's really a tribute to fieldworkers such as Robert Broom and Bob Brain [who worked at Swartkrans] that this research could even take place. It's also an example of why we need to continue to look for fossils after we think we know what a species is -- more specimens allow us to answer more interesting questions. Even isolated teeth can give us new insights into what variation means."
Dr Lockwood adds: "The pattern of growth also gives a better understanding of who is male and who is female in this sample of skulls and it turns out that there are far more males in the fossil sample. Because fossils from the most prolific site, Swartkrans, are thought to have been deposited by predators such as leopards and hyenas, it appears that males were getting killed more often than females.
"Basically, males had a high-risk, high-return lifestyle in this species. They most likely left their birth groups at about the time they reached maturity, and it was a long time before they were mature enough to attract females and establish a new group. Some of them were killed by predators before they got the chance."
A final point made by the researchers is that not all fossil hominin samples show the same patterns, and it is quite possible that further work will reveal clear diversity in social structure between human ancestors, in the same way that one sees differences among apes such as chimpanzees, bonobos, gorillas, and orangutans. This research will help us to understand how human social structure evolved.
This research was published in the journal Science on November 30, 2007.
Research at Drimolen has been funded by the Leakey Foundation, the Department of Science and Technology in South Africa, the Italian Ministry of Foreign Affairs, and the Italian Cultural Institute in Pretoria. The Royal Society supported Charles Lockwood's work in South Africa.
Fossils are housed at the University of the Witwatersrand in Johannesburg and the Transvaal Museum (Northern Flagship Institution), Pretoria.
Adapted from materials provided by University College London.

Fausto Intilla

www.oloscience.com

More Than One-quarter Of US Bird Species Imperiled, Report States

Source:

http://www.sciencedaily.com/releases/2007/11/071129083858.htm

ScienceDaily (Nov. 29, 2007) — One hundred seventy-eight species in the continental U.S. and 39 in Hawaii have the dubious distinction of landing on the newest and most scientifically sound list of America's most imperiled birds. WatchList 2007, a joint effort of Audubon and American Bird Conservancy, reflects a comprehensive analysis of population size and trends, distribution, and threats for 700 bird species in the U.S. It reveals those in greatest need of immediate conservation help simply to survive amid a convergence of environmental challenges, including habitat loss, invasive species and global warming.

"We call this a 'WatchList' but it is really a call to action, because the alternative is to watch these species slip ever closer to oblivion," said Audubon Bird Conservation Director and co-author of the new list, Greg Butcher. "Agreeing on which species are at the greatest risk is the first step in building the public policies, funding support, innovative conservation initiatives and public commitment needed to save them."
The new Audubon/American Bird Conservancy WatchList identifies 59 continental and 39 Hawaiian "red list" species of greatest concern, and 119 more in the "yellow" category of seriously declining or rare species. It is based on the latest available research and assessment from the bird conservation community along with data from the Christmas Bird Count and the annual Breeding Bird Survey. The data were analyzed and weighted according to methods developed through extensive peer review and revision, yielding an improved assessment of actual peril that can be used to determine bird conservation priorities and funding.
"Adoption of this list as the 'industry standard' will help to ensure that conservation resources are allocated to the most important conservation needs," said David Pashley, American Bird Conservancy's Director of Conservation Programs and co-author of the new list. "How quickly and effectively we act to protect and support the species on this list will determine their future; where we've taken aggressive action, we've seen improvement."
Despite ongoing challenges and their continued place on the list, the status of some WatchList species is improving, according to the new data, as broader awareness of their plight has spawned effective conservation action. Several species have benefited from federal protection under the Endangered Species Act (ESA) and now show stabilizing, or even increasing populations. Lacking an ESA designation or the political support needed to secure strong protective measures, others continue to decline.
"Habitat loss due to development, energy exploration and extraction, and the impact of global warming remain serious threats for the most imperiled species, along with others on both the red and yellow lists," said Pashley. "Concerted action will be needed to address these threats."
Listed species may seem unfamiliar to many Americans. Unlike those on Audubon's recent survey of Common Birds in Decline, the species on WatchList are often rare and limited in range. In combination with population declines and new threats, these factors make many of them acutely vulnerable to extinction.
Among the most imperiled species on the list that regularly breed in the continental U.S. are:
Gunnison Sage-Grouse (not on ESA list)
This species is restricted to Southwest Colorado and adjacent Utah. Drought, which is predicted to get worse with increased global warming, is among the factors that have reduced the Gunnison Sage-Grouse population to fewer than 5,000; habitat loss and fragmentation and excessive grazing are other threats. Protection and restoration of contiguous tracts of good habitat is critical.
Lesser Prairie-Chicken (not on ESA list)
Habitat loss and degradation have restricted this species to a number of isolated populations, many of which are on private lands in Kansas, Colorado, Oklahoma, New Mexico, and Texas. Small population size, changing habitat resulting from drought, and climate change threaten continued survival.
California Condor (protected by ESA)
Once reduced to nine individual wild birds, this raptor is slowly recovering, thanks to captive breeding and the release of individuals in California and Arizona. There are now 305 individuals, including 148 free-flying birds. Lead bullets are a critical threat to long-term survival, as fragments poison wild condors that eat the remains of hunters' kills. Audubon California and American Bird Conservancy have spearheaded recent passage of legislation eliminating lead bullets in the range of the condor in that state.
Whooping Crane (protected by ESA)
Unregulated shooting and loss of habitat reduced this species to fewer than 20 individuals around the turn of the 20th Century. Implementation of a recovery plan developed under the Endangered Species Act has resulted in more than a 1000% increase in population to over 200 individuals, and has spawned efforts to establish additional wild breeding populations.
Piping Plover (protected by ESA)
Protection of this shorebird's beachfront nesting grounds is helping to improve the outlook for this species. Human development along beaches, increased beach recreation, disturbance by pets, and increased predation require constant vigilance. Intensive conservation efforts supported by the Endangered Species Act have helped stabilize populations and allowed populations to increase in some regions of the Atlantic and Gulf coasts.
Black-capped Vireo (protected by ESA)
Suburban development, agricultural conversion, and fire suppression in Texas and Oklahoma have decreased available breeding habitat, reducing both the range and population size of this species. Increased predation near human development has further decreased populations, as has parasitism from Brown-headed Cowbirds, which lay their eggs in Black-capped Vireo nests, out-competing the vireo chicks. Innovative conservation efforts on public and private lands seem to be helping some populations recover.
Florida Scrub-Jay (protected by ESA)
Suburban-exurban sprawl and agricultural development have reduced habitat dramatically and isolated many populations. Maintaining natural wildfire regimes will be critical. Although ESA status has increased conservation efforts for this species, it has not been enough to stop loss of habitat.
Golden-cheeked Warbler (protected by ESA)
Breeding is restricted to the Edwards Plateau in Texas, where suburban sprawl and habitat destruction has greatly reduced population size. Winter habitat loss in southern Mexico and Central America may also be affecting populations. Innovative conservation strategies that protect and restore habitat in both the breeding and wintering grounds are underway and needed.
Kirtland's Warbler (protected by ESA)
Dependent on jack pine habitat in northern Michigan, this warbler species has increased more than 600% since the mid-1980s because of management plans implemented under the Endangered Species Act. Singing male counts in the spring have increased from 200 to almost 1,400 (and some singing males are now found in Wisconsin and Ontario). Wild land fire management, control of the parasitic Brown-headed Cowbird, and protection of wintering habitat in the Bahamas remain essential to long-term survival.
Ashy Storm-Petrel (not on ESA list)
Breeding populations are restricted to islands off the west coast of North America. Non-native nest predators and increased gull populations threaten breeding birds, and ocean pollution and overfishing threaten feeding birds.
Kittlitz's Murrelet (not on ESA list)
Breeding and feeding habitat seems to be linked to Alaska's tidewater glaciers, making this species very susceptible to climate change. Oil spills, coastal pollution, and increased disturbance also threaten this species.
Red-cockaded Woodpecker (protected by ESA)
Habitat loss from logging in the Southeast's long-leaf pine forests and suburban and agricultural development have isolated populations and greatly reduced overall population size. Protection strategies developed through the Endangered Species Act are helping populations in many places, but restoration of open long-leaf pine forest is desperately needed.
Spectacled Eider (protected by ESA)
Ingestion of lead shot is believed to be a major problem for this species, along with an increase in nest predation by foxes, mink, gulls, and jaegers in a warming Arctic. In addition, changing sea conditions in winter are affecting the distribution of clams - a preferred winter food. Proposed oil development poses an additional and very significant threat.
Reddish Egret (not on ESA list)
This species forages along the Gulf Coast and is subject to human disturbance at beaches and at nesting sites. It is dependent on high quality coastal habitat for its food. Human coastal development and decreasing water quality are serious threats.
Black Rail (not on ESA list)
This species makes its home in shallow, grassy wetlands along the Atlantic Coast, San Francisco Bay, southern Great Plains and the Lower Colorado River, habitat that is vulnerable to human conversion to other uses, including agriculture or other development. A secretive bird, it needs further study to increase understanding of its natural history, ecological role and conservation needs.
Buff-breasted Sandpiper (not on ESA list)
Traveling each fall from Alaska to Argentina, this species is one of our champion long-distance migrants. Along the way, it faces a great variety of threats, from oil development on its Arctic breeding grounds to grassland conversion to soybean fields on its Argentinean wintering grounds. It needs protected grassy stopover sites all along its migration route.
Saltmarsh Sharp-tailed Sparrow (not on ESA list)
This tiny bird is restricted to a narrow band of saltmarsh along the Atlantic and Gulf Coasts. It is threatened on one side by human coastal developments and on the other by rising sea levels. With even one foot of sea-level rise from global warming, this species will need a lot of help to maintain sufficient habitat for its survival.
Tricolored Blackbird (not on ESA list)
A highly social species, this bird is found in freshwater wetlands in the Pacific states, mainly California. With loss of this habitat, this species increasingly relies on agricultural fields for nesting, leaving chicks vulnerable to the harvest of hay and other crops. Audubon California and other conservationists are working with farmers to maintain agricultural nesting habitat long enough each season to allow the blackbirds to successfully raise their young - potentially spelling the difference between survival and extinction for this highly specialized bird.
Yellow Rail (not on ESA list)
Rails are small, secretive birds that winter in wetlands along the Gulf and Atlantic Coasts. This species prefers to breed in wet grasslands across Canada and the northern tier of states from Minnesota to Maine. These grasslands are easily converted to other uses, so protection of high-quality habitat will be essential for this migratory bird's survival.
Xantus's Murrelet (not on ESA list)
This tiny seabird nests on islands off southern California. Conservationists are tackling the major threat on the nesting grounds - non-native predators like rats and mice. Global warming seems to wreak havoc with the water circulation and availability of food sources in the ocean, causing shortages for this and other coastal seabirds.
Conservation action is also needed beyond the mainland. Hawaii has the highest proportion of native species in peril, primarily because of the state's small land area and wide variety of introduced invasive animal and plant species. In addition, the Hawaiian Islands are particularly vulnerable to global warming. Hawaiian species facing the greatest threats are highlighted in a special section of WatchList.
The combined WatchLists show that imperiled birds - whether on the U.S. mainland or in Hawaii - are vulnerable to many of the same environmental threats, including global warming, habitat loss, pollution, and non-native invasive species. Aggressive conservation action to address these challenges is essential to their survival. "Everyone, from conservation groups to policy-makers and birdwatchers, needs to take a hard look at these lists and use them to inform and hone our conservation approaches and funding priorities while there's still time," says Butcher. "It's astounding that several are so close to the edge but haven't even received Endangered Species Act protection-this list is a reminder that we need to act and act now."
"The WatchList sounds a real warning, but fortunately, when we put our minds and laws to it, as we did with the Bald Eagle, Whooping Crane and California Condor, we can make a difference," said Pashley.
Adapted from materials provided by National Audubon Society.

Fausto Intilla

www.oloscience.com

Dogs Can Classify Complex Photos In Categories Like Humans Do

Source:

http://www.sciencedaily.com/releases/2007/11/071128105543.htm

ScienceDaily (Nov. 29, 2007) — Like us, our canine friends are able to form abstract concepts. Friederike Range and colleagues from the University of Vienna in Austria have shown for the first time that dogs can classify complex color photographs and place them into categories in the same way that humans do. And the dogs successfully demonstrate their learning through the use of computer automated touch-screens, eliminating potential human influence.

In order to test whether dogs can visually categorize pictures, and transfer their knowledge to new situations, four dogs were shown landscape and dog photographs, and expected to make a selection on a computer touch-screen.
In the training phase, the dogs were shown both the landscape and dog photographs simultaneously and were rewarded with a food pellet if they selected the dog picture (positive stimulus). The dogs then took part in two tests.
In the first test, the dogs were shown completely different dog and landscape pictures. They continued to reliably select the dog photographs, demonstrating that they could transfer their knowledge gained in the training phase to a new set of visual stimuli, even though they had never seen those particular pictures before.
In the second test, the dogs were shown new dog pictures pasted onto the landscape pictures used in the training phase, facing them with contradictory information: on the one hand, a new positive stimulus as the pictures contained dogs even though they were new dogs; on the other hand, a familiar negative stimulus in the form of the landscape.
When the dogs were faced with a choice between the new dog on the familiar landscape and a completely new landscape with no dog, they reliably selected the option with the dog. These results show that the dogs were able to form a concept i.e. ‘dog’, although the experiment cannot tell us whether they recognized the dog pictures as actual dogs.
The authors also draw some conclusions on the strength of their methodology: “Using touch-screen computers with dogs opens up a whole world of possibilities on how to test the cognitive abilities of dogs by basically completely controlling any influence from the owner or experimenter.” They add that the method can also be used to test a range of learning strategies and has the potential to allow researchers to compare the cognitive abilities of different species using a single method.
Journal reference: Range F et al (2007). Visual categorization of natural stimuli by domestic dogs (Canis familiaris). Animal Cognition (DOI 10.1007/s10071-007-0123-2).
Adapted from materials provided by Springer.


Fausto Intilla
www.oloscience.com

Mediterranean Sea: Most Dangerous Place On Earth For Sharks And Rays

Source:

http://www.sciencedaily.com/releases/2007/11/071126141041.htm

ScienceDaily (Nov. 27, 2007) — The first complete IUCN Red List assessment of the status of all Mediterranean sharks and rays has revealed that 42% of the species are threatened with extinction. Overfishing, including bycatch (non-target species caught incidentally), is the main cause of decline, according to the research.

The report, released November 15 by the IUCN Shark Specialist Group and the IUCN Centre for Mediterranean Cooperation, shows that the region has the highest percentage of threatened sharks and rays in the world.
“From devil rays to angel sharks, Mediterranean populations of these vulnerable species are in serious trouble,” said Claudine Gibson, Programme Officer for the IUCN Shark Specialist Group and co-author of the report. “Our analyses reveal the Mediterranean Sea as one of the world’s most dangerous places on Earth for sharks and rays. Bottom dwelling species appear to be at greatest risk in this region, due mainly to intense fishing of the seabed.”
The report also identifies habitat degradation, recreational fisheries, and other human disturbances as significant threats to the sharks and rays of the Mediterranean.
These are the findings of an expert workshop at which 71 Mediterranean species of sharks, rays and chimaeras (cartilaginous fishes) were assessed using IUCN Red List categories and criteria. Participants deemed 30 species as threatened with extinction, of which 13 are classified at the highest threat level of Critically Endangered, eight as Endangered and nine as Vulnerable. Another 13 species were assessed as Near Threatened, while a lack of information led to 18 species being classified as Data Deficient. Only 10 species are considered to be of Least Concern.
The Maltese Skate (Leucoraja melitensis), found only in the Mediterranean, is assessed as Critically Endangered. Bottom trawl fisheries are the main cause for population declines of 80%. The angular roughshark (Oxynotus centrina) and three species of angel sharks (Squatina spp.) are also Critically Endangered.
The giant devil ray (Mobula mobular), which occurs primarily in the Mediterranean, is considered Endangered. Females can grow to five meters (17 feet) and give birth to only one pup per pregnancy. This large size and low reproductive capacity make devil rays especially vulnerable to capture and entanglement in various net fisheries, including illegal driftnets.
The shortfin mako (Isurus oxyrinchus) and porbeagle (Lamna nasus), both prized for their meat and fins, were found to be Critically Endangered in the Mediterranean. The sandbar shark (Carcharhinus plumbeus) is listed as Endangered in the region and even the relatively prolific blue shark (Prionace glauca) is considered Vulnerable to extinction here.
“We are particularly concerned about the porbeagle and mako sharks in the Mediterranean,” warned Dr Alen Soldo of the University of Split in Croatia, an expert on oceanic sharks who participated in the workshop. “Our studies reveal persistent fishing pressure well in excess of the reproductive capacity of the species, which led to our decision to categorize them in the highest threat category under the Red List criteria.”
Only one species, the Portuguese dogfish (Centroscymnus coelolepis), has a better conservation status inside the Mediterranean Sea, where it is considered of Least Concern, than globally (Near Threatened). This deep sea shark is found at depths of nearly 4,000 meters and may be protected by a 2005 ban on fisheries below 1,000 meters by the General Fisheries Commission of the Mediterranean (GFCM).
Protection measures in place and more needed
This deepwater fishing ban, along with prohibitions on driftnets and shark finning (slicing off a shark’s valuable fins and discarding the body at sea) may help to lift some of the pressure on sharks and rays in the Mediterranean. However, better enforcement is required to give cartilaginous fish populations a chance to recover.
There are no catch limits for fished species of Mediterranean sharks and rays. Eight species of sharks and rays have been listed on the four international conventions relevant to Mediterranean wildlife conservation, but only three species have received any protection as a result: white and basking sharks are protected in Croatian and European Community waters, while Malta and Croatia protect the giant devil ray.
This week, in Turkey, international fisheries managers are expected to discuss limits on fishing for porbeagle and shortfin mako sharks at the annual meeting of the International Commission for the Conservation of Atlantic Tunas (ICCAT), which guides Mediterranean rules for species taken in tuna fisheries.
“Never before have Mediterranean countries had more reason or opportunity to safeguard the region’s beleaguered sharks and rays,” said Sonja Fordham, Deputy Chair of the SSG and Policy Director for the Shark Alliance. “Country officials should heed the dire warnings of this report and act to protect threatened sharks and rays through regional fisheries agreements, international wildlife conventions, and national legislation. Such action is necessary to change the current course toward extinction of these remarkable ocean animals.”
The report aims to assist in policy development for the conservation and sustainable use of Mediterranean cartilaginous fishes and provides a range of recommendations to that end. Conservation and fisheries organizations need to collaborate to ensure these measures are urgently implemented to curb the decline of sharks and rays in the region and to also guarantee the sustainability of marine resources - fundamental to the livelihoods of Mediterranean societies.
“Once again, the main concern is not only for each individual species – as important as they are – but for the cumulative impact of this loss of biodiversity,” said Annabelle Cuttelod, Mediterranean Red List Coordinator at the IUCN Centre for Mediterranean Cooperation. “We are observing serious changes which will have major consequences over time on all animal life and, ultimately, on the livelihoods of people around the Mediterranean.”
The IUCN Centre for Mediterranean Cooperation is currently assessing the status of marine fish in the Mediterranean, in collaboration with the IUCN Species Programme and the Turkish Marine Research Foundation (TUDAV). About 30 experts are meeting in Istanbul, Turkey, from 12 to 16 November to analyze this issue.
The report is entitled “Overview of the Conservation Status of Cartilaginous Fishes (Chondrichthyans) in the Mediterranean Sea” by Rachel D. Cavanagh and Claudine Gibson and is the third in a series of Mediterranean Regional Assessments.
About sharks in the ecosystem
Most sharks and rays are exceptionally vulnerable to overfishing because of their tendency to grow slowly, mature late, and produce few young.
Most sharks play key roles as top predators in marine food webs. By feeding on the weak and wounded of prey species, sharks help maintain ocean ecosystem function.
Adapted from materials provided by World Conservation Union.

Fausto Intilla

www.oloscience.com

Flowering Plants Evolved Very Quickly Into Five Groups

Source:

http://www.sciencedaily.com/releases/2007/11/071126170900.htm

ScienceDaily (Nov. 27, 2007) — University of Florida and University of Texas at Austin scientists have shed light on what Charles Darwin called the "abominable mystery" of early plant evolution.

The scientists are reporting that the two largest groups of flowering plants are more closely related to each other than any of the other major lineages. These are the monocots, which include grasses and their relatives, and the eudicots, which include sunflowers and tomatoes.
Doug and Pam Soltis, a UF professor of botany and curator at UF's Florida Museum of Natural History, respectively, also showed that a stunning diversification of flowering plants they are referring to as the "Big Bang" took place in the comparatively short period of less than 5 million years -- and resulted in all five major lineages of flowering plants that exist today.
"Flowering plants today comprise around 400,000 species," said Pam Soltis. "So to think that the burst that give rise to almost all of these plants occurred in less than 5 million years is pretty amazing -- especially when you consider that flowering plants as a group have been around for at least 130 million years."
The lead author of the UF paper is Michael Moore, a former postdoctoral associate in the Soltis lab and current faculty member at Oberlin College. Charles Bell, the fourth author, is another former Soltis postdoctoral associate, now at the University of New Orleans.
Robert Jansen, professor of integrative biology at The University of Texas at Austin, said the two papers set the stage for all future comparative studies of flowering plants.
"If you are interested in understanding the evolution of flowering plants, you can't do that unless you understand their relationships," he said.
Botanists predating Darwin have long recognized that flowering plants, which comprise at least 60 percent of all green plant species, diversified abruptly shortly after they appeared.
The details, and especially the cause of, this diversification -- Darwin's "abominable mystery" -- has been a hot topic in botany ever since.
"One of the reasons why it's been hard to understand evolutionary relationships among the major groups of flowering plants is because they diversified over such a short time frame," Jansen said.
Seeking to distill the cloudy picture into a clear one, the UF and UT researchers analyzed DNA sequences from the completely sequenced genomes of the chloroplast. That organelle, responsible for plants' ability to photosynthesize, is shared by all green plants.
Jansen and his UT Austin colleagues analyzed DNA sequences of 81 genes from the chloroplast genome of 64 plant species, while the UF researchers analyzed 61 genes from 45 species. The two groups also performed a combined analysis, which produced evolutionary trees that included all the major groups of flowering plants.
The analyses also confirmed that a unique species of plant called Amborella, found only on the Pacific island of New Caledonia, represents the earliest diverging lineage of flowering plants.
By laboriously arranging the sequences, the researchers slowly built a kind of family tree for plants -- a diagram of relationships among plant lineages showing diversification over the eons. Based on known rates of genetic change double-checked against fossils of known ages, they established a time scale that revealed the dates of major branching events.
Based on the Soltises' and their collaborators' research in previous years, it was known that flowering plants split into three branches shortly after they appeared about 130 million years ago. That process was relatively gradual, at least compared with the rapid radiation that happened next. The details of that radiation have long been murky. The latest research clears the picture by showing that all plants fall into five major lineages that developed over the relatively short period of 5 million years, or possibly even less.
As for the diversification's cause, it remains mysterious, Pam and Doug Soltis said.
It's possible it was spurred by some major climatic event. It's also possible that a new evolutionary trait -- a water-conducting cell that transfers water up plant stems -- proved so effective that it spurred massive plant species diversification. The cell is either not present, or is poorly developed, in the first three flowering plant lineages, Doug Soltis said. The earliest flowering plant lineages also did not have a completely fused ovary, which in later flowering plants may better protect the seeds, Pam Soltis said.
Two papers on this research are set to be published in the beginning of December in the Proceedings of the National Academy of Sciences.
Adapted from materials provided by University of Florida.

Fausto Intilla

www.oloscience.com

Climate Change Triggers Wars And Population Decline, Study Shows

Source:

http://www.sciencedaily.com/releases/2007/11/071121112917.htm

ScienceDaily (Nov. 26, 2007) — Climate change may be one of the most significant threats facing humankind. A new study shows that long-term climate change may ultimately lead to wars and population decline.

The study revealed that as temperatures decreased centuries ago during a period called the Little Ice Age, the number of wars increased, famine occurred and the population declined.
Data on past climates may help accurately predict and design strategies for future large and persistent climate changes, but acknowledging the historic social impact of these severe events is an important step toward that goal, according to the study's authors.
"Even though temperatures are increasing now, the same resulting conflicts may occur since we still greatly depend on the land as our food source," said Peter Brecke, associate professor in the Georgia Institute of Technology's Sam Nunn School of International Affairs and co-author of the study.
This new study* expands previous work by David Zhang of the University of Hong Kong and lead author of the study.
"My previous research just focused on Eastern China. This current study covers a much larger spatial area and the conclusions from the current research could be considered general principles," said Zhang.
Brecke, Zhang and colleagues in Hong Kong, China and the United Kingdom perceived a possible connection between temperature change and wars because changes in climate affect water supplies, growing seasons and land fertility, prompting food shortages. These shortages could lead to conflict -- local uprisings, government destabilization and invasions from neighboring regions -- and population decline due to bloodshed during the wars and starvation.
To study whether changes in temperature affected the number of wars, the researchers examined the time period between 1400 and 1900. This period recorded the lowest average global temperatures around 1450, 1650 and 1820, each separated by slight warming intervals.
The researchers collected war data from multiple sources, including a database of 4,500 wars worldwide that Brecke began developing in 1995 with funding from the U.S. Institute of Peace. They also used climate change records that paleoclimatologists reconstructed by consulting historical documents and examining indicators of temperature change like tree rings, as well as oxygen isotopes in ice cores and coral skeletons.
Results showed a cyclic pattern of turbulent periods when temperatures were low followed by tranquil ones when temperatures were higher. The number of wars per year worldwide during cold centuries was almost twice that of the mild 18th century.
The study also showed population declines following each high war peak, according to population data Brecke assembled. The population growth rate of the Northern Hemisphere was elevated from 1400-1600, despite a short cooling period beginning in the middle of the 15th century. However, during the colder 17th century, Europe and Asia experienced more wars of great magnitude and population declines.
In China, the population plummeted 43 percent between 1620 and 1650. Then, a dramatic increase in population occurred from 1650 until a cooling period beginning in 1800 caused a worldwide demographic shock.
The researchers examined whether these average temperature differences of less than one degree Celsius were enough to cause food shortages. By assuming that agricultural production decreases triggered price increases, they showed that when grain prices reached a certain level, wars erupted. The ecological stress on agricultural production triggered by climate change did in fact induce population shrinkages, according to Brecke.
Global temperatures are expected to rise in the future and the world's growing population may be unable to adequately adapt to the ecological changes, according to Brecke.
"The warmer temperatures are probably good for a while, but beyond some level plants will be stressed," explained Brecke. "With more droughts and a rapidly growing population, it is going to get harder and harder to provide food for everyone and thus we should not be surprised to see more instances of starvation and probably more cases of hungry people clashing over scarce food and water."
*This new study was published November 19 in the early edition of the journal Proceedings of the National Academy of Sciences.
Adapted from materials provided by Georgia Institute of Technology.

Fausto Intilla

www.oloscience.com

Unraveling the Silky Spider Web

Source:

http://www.sciencedaily.com/releases/2007/11/071121144937.htm

ScienceDaily (Nov. 25, 2007) — Web-making spiders employ a host of silk glands to synthesize a variety of silk filaments with different mechanical properties. Although it is widely believed that the aciniform glands are one such silk factory, there has been no hard evidence linking aciniform-derived proteins and silk --until now.

Craig Vierra and colleagues found that the aciniform gland in the Black Widow manufactures and extrudes a previously unidentified protein that is a component of multiple types of silk.
Vierra and colleagues used mass spectroscopy to analyze the protein content of two types of silk: the variety used for egg cases and the one used to wrap up prey. In both types they uncovered a thin protein fiber with a similar structure to another known silk protein called AcSp1. When they examined the expression of this new protein, termed AcSp1-like protein, in different silk glands, they found that mRNA levels were present at 1000-fold higher concentration in the aciniform gland compared to other glands.
The researchers note this finding is intriguing since it shows that aciniform silk fibers are not made for one specific task but rather get integrated into multiple silk types. They plan to further characterize the mechanics of aciniform silk, but they propose that this thin fiber acts like twine to hold thicker silk fibers together.
Journal article: "Aciniform spidroin: A constituent of egg case sacs and wrapping silk fibers from the black widow spider, Latrodectus Hesperus" by Keshav Vasanthavada, Xiaoyi Hu, Arnold M. Falick, Coby LaMattina, Anne M.F. Moore, Patrick R. Jones, Russell Yee, Ryan Reza, Tiffany Tuton, and Craig A. Vierra
Adapted from materials provided by American Society for Biochemistry and Molecular Biology.

Fausto Intilla

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Scientists Unravel Plants' Natural Defenses

Source:

http://www.sciencedaily.com/releases/2007/11/071121144953.htm

ScienceDaily (Nov. 26, 2007) — A team of researchers, led by the University of Sheffield and Queen Mary, University of London, has discovered how plants protect their leaves from damage by sunlight when they are faced with extreme climates. The new findings, which have been published in Nature, could have implications both for adapting plants to the threat of global warming and for helping man better harness solar energy.

Photosynthesis in plants relies upon the efficient collection of sunlight. This process can work even at low levels of sunlight, when plants are in the shade or under cloud cover for example. However, when the sun is very bright or when it is cold or very dry, the level of light energy absorbed by leaves can be greatly in excess of that which can be used in photosynthesis and can destroy the plant. However, plants employ a remarkable process called photoprotection, in which a change takes place in the leaves so that the excess light energy is converted into heat, which is harmlessly dispersed.
Until now, researchers hadn't known exactly how photoprotection works. By joining forces with their physicist colleagues in France and the Netherlands, the UK team have determined how this process works. They were able to show how a small number of certain key molecules, hidden among the millions of others in the plant leaf, change their shape when the amount of light absorbed is excessive; and they have been able to track the conversion of light energy to heat that occurs in less than a billionth of a second.
Many plant species can successfully inhabit extreme environments where there is little water, strong sunlight, low fertility and extremes of temperature by having highly tuned defence mechanisms, including photoprotection. However, these mechanisms are frequently poorly developed in crop plants since they are adapted for high growth and productivity in an environment manipulated by irrigation, fertilisation, enclosure in greenhouses and artificial shading. These manipulations are not sustainable, they have high energy costs and may not be adaptable to an increasingly unstable climate. Researchers believe that in the future, the production of both food and biofuel from plants needs to rely more on their natural defence mechanisms, including photoprotection.
Professor Horton, of the University of Sheffield's Department of Molecular Biology and Biotechnology, who lead the UK team, said: "These results are important in developing plants with improved photoprotective mechanisms to enable them to better cope with climate change. This may be hugely significant in our fight against global warming. It is a fantastic example of what can be achieved in science when the skills of biologists and physicists are brought together."
Moreover, there are other global implications of this research. Dr Alexander Ruban of Queen Mary's School of Biological and Chemical Sciences, comments: "As we seek to develop new solar energy technology it will be important to not only understand, but to mimic the way biology has learnt to optimise light collection in the face of the continually changing intensity of sunlight."
The paper, Identification of a mechanism of photoprotective energy dissipation in higher plants, will be published in Nature on 22 November 2007.
The research project is a collaboration between the University of Sheffield, UK; Queen Mary, University of London, UK; the University of Amsterdam, Netherlands; the University of Wageningen, Netherlands; CEA Saclay and CNRS Gif-sur-Yvette, France.
The work was supported by grants from UK Biotechnology and Biological Sciences Research Council, the Netherlands Organization for Scientific Research via the Foundation of Earth and Life Sciences, Laserlab Europe; ANR, and the Marie Curie Research Training Network.
Adapted from materials provided by University of Sheffield.

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Carnivorous Plants Use Pitchers Of 'Slimy Saliva' To Catch Their Prey

Source:

http://www.sciencedaily.com/releases/2007/11/071120201931.htm

ScienceDaily (Nov. 24, 2007) — Carnivorous plants supplement the meager diet available from the nutrient-poor soils in which they grow by trapping and digesting insects and other small arthropods. Pitcher plants of the genus Nepenthes were thought to capture their prey with a simple passive trap but in a paper in PLoS One, Laurence Gaume and Yoel Forterre, a biologist and a physicist from the CNRS, working respectively in the University of Montpellier and the University of Marseille, France show that they employ slimy secretions to doom their victims.

They show that the fluid contained inside the plants' pitchers has the perfect viscoelastic properties to prevent the escape of any small creatures that come into contact with it even when diluted by the heavy rainfall of the forest of Borneo in which they live.
Since Charles Darwin's time, the mechanism of insect-trapping by Nepenthes pitcher plants from the Asian tropics has intrigued scientists but is still incompletely understood. The slippery inner surfaces of their pitchers have -- until now -- been considered the key trapping devices, while it was assumed that the fluid secretions were only concerned with digestion.
Gaume and Forterre were able to combine their separate expertise in biology and physics to show that the digestive fluid of Nepenthes rafflesiana actually plays a crucial role in prey capture.
The pair took high-speed videos of flies and ants attempting to move through plants' fluid. Flies quickly became completely coated in the fluid and unable to move even when diluted more than 90% with water. Physical measurements on the fluid showed that this was because this complex fluid generates viscoelastic filaments with high retentive forces that give no chance of escape to any insect that has fallen into it and that is struggling in it.
That the viscoelastic properties of the fluid remain strong even when highly diluted is of great adaptive significance for these tropical plants which are often subjected to heavy rainfalls.
For insects, this fluid acts like quicksand: the quicker they move, the more trapped they become. Its constituency is closely akin to mucus or saliva, which, in some reptiles and amphibians, serves a very similar purpose.
The exact makeup of this fluid, apparently unique in the plant kingdom, remains to be determined; however, it may point the way to novel, environmentally friendly approaches to pest control.
Citation: Gaume L, Forterre Y (2007) A Viscoelastic Deadly Fluid in Carnivorous Pitcher Plants. PLoS One 2(11): e1185. doi:10.1371/journal.pone.0001185
Adapted from materials provided by Public Library of Science.

Fausto Intilla

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Delay In Autumn Color Caused By Increased Carbon Dioxide Not Global Warming

Source:

http://www.sciencedaily.com/releases/2007/11/071117104404.htm

ScienceDaily (Nov. 18, 2007) — The delay in autumnal leaf coloration and leaf fall in trees is caused by rising levels of carbon dioxide (CO2) in the atmosphere and not by increased global temperatures, suggests a new study by researchers at the University of Southampton.

In recent years, woodland autumnal colour changes have been occurring later in the season whilst re-greening in spring has been occurring earlier. During the last 30 years across Europe, autumnal senescence – the process of plant aging where leaves discolour and then fall – has been delayed by 1.3 - 1.8 days a decade. To date, this has been explained by global warming, with increasing temperatures causing longer growing seasons.
However, while a strong correlation has been observed between increased global temperatures and earlier spring re-greening and bud break, the correlation between autumn leaf colour change and fall and temperature trends in 14 European countries is weak.
Over the 30 years that progressive delays in autumnal senescence have been observed, atmospheric CO2 has risen by 13.5 per cent. Experimental studies show that increased atmospheric CO2 affects plant physiology and function, influencing a myriad of processes.
The Southampton researchers undertook two large forest ecosystem experiments in which poplar (Populus) trees in separate plots were exposed to either ambient or elevated levels of CO2 from planting to maturity. The elevated concentration was at 550 parts per million, proposed as representative of concentrations that may occur in 2050. Changes in the tree canopy were measured by remote sensing.
The trees exposed to elevated CO2 retained their leaves for longer and also experienced a smaller decline in end of season chlorophyll content, resulting in a greener autumn canopy relative to that in ambient CO2.
Professor Gail Taylor, of the University’s School of Biological Sciences, explains:
‘The research data provide compelling evidence in terms of both the leaf and canopy that autumnal senescence in such forest ecosystems will be delayed as the atmospheric concentration of CO2 continues to rise, independent of increased temperatures.
‘Photosynthesis and canopy greenness are maintained for longer in elevated CO2. This is because a CO2 rich atmosphere allows the tree to generate carbon rich compounds that are known to prolong the life of leaves. These compounds may have a positive effect for carbon balance and stress tolerance but may also have a negative effect on the control of dormancy.
‘When trees keep their leaves for longer, they continue to photosynthesise but trees also need to set bud and if they don’t do that, it makes them susceptible to frost and other weather events. A key question now is whether we should be selecting trees which are better adapted to coping with increasing levels of CO2, perhaps considering different varieties and species to plant, rather than using locally sourced seed, as is current practice,’ she continues.
The study also provides the first insight into changes in the genetic make-up of Populus that can account for this shift to delayed senescence. Using cDNA microarrays, the researchers looked at approximately 20,000 genes and have identified a suite of genes that are switched on during delayed senescence in elevated CO2.
Adapted from materials provided by University of Southampton.

Fausto Intilla

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Why Do So Many Species Live In Tropical Forests And Coral Reefs?

Source:

http://www.sciencedaily.com/releases/2007/10/071031152950.htm

ScienceDaily (Nov. 6, 2007) — The latest development in a major debate over a controversial hypothesis of biodiversity and species abundance is the subject of a paper to be published in the 1 November 2007 issue of the journal Nature. The authors report good agreement between the species richness of two of the world's most vulnerable ecosystems -- tropical forests and coral reefs -- and a simple mathematical model building on the so-called "neutral theory of biodiversity."

"We're helping to refine and improve this theory because it might have important implications for the effort to protect terrestrial biodiversity from climate change and urban development," says Jayanth Banavar of the Department of Physics at Penn State, a member of the research team.
The Nature paper is based on a counterintuitive assumption of neutral theory: that one can largely ignore interactions between species in modeling patterns of species abundance. The authors are physicists Igor Volkov and Jayanth Banavar of Penn State University, plant biologist Stephen Hubbell of UCLA (formerly of the University of Georgia), and physicist Amos Maritan of the University of Padua in Italy.
Among ecological theorists, neutral theory has sparked a six-year quarrel over the fundamental assumptions of their discipline. The Nature paper counters another scientific team's claim in 2006 that coral-reef diversity "refutes" the neutral theory. At the same time, the paper by Volkov et al., to be published on 1 November 2007, modifies the classical version of neutral theory that appeared in a 2001 book by Hubbell. (Graham Bell of McGill University also developed a neutral theory independently of Hubbell.) Banavar, Maritan, Volkov, and their collaborators have been active in the development of a mathematical framework for understanding ecosystems that builds on and clarifies Hubbell's neutral theory.
"Despite its controversial nature, neutral theory has proved to be a good starting point for understanding ecosystems," Maritan says. In a 2005 paper published in Nature, Banavar, Maritan, Volkov, and their collaborators demonstrated that tree-species abundance and diversity in the tropical forests can be explained by the density-dependence mechanism, in which birth, death, and migration processes are postulated to depend on the abundance of a species. In a Nature paper in 2006, they presented a theory for the time scales of neutral evolution that is in good accord with empirical data.
"Mathematical modeling is increasingly vital in the biological sciences, and the key challenge is to uncover the simplicity underlying the seemingly bewildering complexity," Banavar says. In recent years, theorists have struggled to reconcile neutral theory with more mainstream ecological models, such as the famous niche theory, according to which species survive by exploiting ecological "niches" to which they are uniquely and better adapted than other species.
For example, a rare plant species might survive in a dense rainforest habitat by exploiting a peculiar soil composition for which it is genetically adapted. Niche theory seemed so commonsensical that many ecological theorists reacted fiercely when Hubbell published his hypothesis, because it implied that individual members of plant or animal species comprising a fixed total population could be modeled as if they were equivalent entities in a random evolutionary lottery influenced only by rates of birth, death, and immigration.
In Hubbell's 2001 book, The Unified Neutral Theory of Biodiversity and Biogeography, he pointed to a surprising feature of some measurements of relative species abundance distributions (RSAs). The measurements are indistinguishable from fictional distribution curves generated by models based on random processes; that is, processes in which the fates of hypothetical species owe purely to chance events in birth, death, and immigration rather than to their adaptive prowess.
Of course, in real life, adaptation to niches is an obvious feature of living creatures. For example, polar bears are adapted to the chilly niche of the Arctic, not to the sultry niche of the tropics. Still, Hubbell's findings hinted that the abundance of species and the development of ecological communities and ecosystems owe more to chance processes, and less to biology, than previously had been assumed.
Since 2001, numerous researchers have published the results of field tests of Hubbell's theory, based on their analyses of life forms and habitats such as tropical forests, North American birds, tropical reef fishes and corals, marine benthic communities in intertidal zones, and pollen records of eastern North American during the Holocene. Test results have varied from strongly positive to strongly negative. Some groups have disagreed in their interpretations of the same data.
In March 2006, Maria Dornelas of James Cook University in Queensland, Australia, and her colleagues published in Nature their study of coral-reef communities in the Indian and Pacific oceans. They found the coral-reef species in various local communities differ from each other far more than expected by neutral theory, and they exhibit RSA patterns that are quite distinct from those of tropical forests.
The Nature article was titled "Coral Reef Diversity Refutes the Neutral Theory of Biodiversity." In their new Nature article, Volkov et al. reply to this latest challenge by arguing that the Dornelas team's thesis is invalid because the spatial structure and degree of isolation of coral-reef communities is different from those of tropical forests. In their latest paper, Banavar, Maritan, Volkov, and their collaborators have reanalyzed the Dornelas dataset and have concluded that it and measurements of rainforest species are compatible with an extended version of neutral theory in which all species are equivalent and do not interact with each other or the environment.
Their work shows that "a theory in which all interspecific interactions are turned off leads to analytical results that are in good agreement with RSA data from tropical forests and coral reefs," the Nature article says. This agreement is so despite the obvious differences between the two types of communities -- coral reefs being composed of "many small, isolated communities" and tropical rainforests being "larger and more connected."
Volkov et al. conclude that "one can make significant theoretical progress in ecology by assuming that the effective interactions are weak in the stationary states in species-rich communities such as tropical forests and coral reefs." Maritan says that ecosystems may have evolved to a stationary state in which the coexisting species are substantially noninteracting because that is the most probable outcome. The next step, Volkov says, is "the development of a framework for bridging neutral and niche theories through the realistic accounting of the most important interactions among species and with the environment; for example, ways in which tree species might compete for the same resources or harbor insect pests that affect their competitiveness with rival tree species."
"The six-year saga of neutral theory is an intriguing example of how a scientific hypothesis can fertilize stimulating new research while evolving over time in response to scientific critiques," Banavar says.
The research was supported by the John D. and Catherine T. MacArthur Foundation, the Mellon Foundation, Earthwatch, Frank Levinson and the Celera Foundation, NASA, the National Science Foundation, and MIUR/Italy.
Adapted from materials provided by Penn State.

Fausto Intilla

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Tiger Numbers Could Be Doubled In South Asia

Source:

http://www.sciencedaily.com/releases/2007/11/071105162902.htm

ScienceDaily (Nov. 6, 2007) — Researchers at the Wildlife Conservation Society and other institutions declare that improvements in management of existing protected areas in South Asia could double the number of tigers currently existing in the region.

Specifically, the study examined 157 reserves throughout the Indian subcontinent--comprising India, Bangladesh, Bhutan, and Nepal. It found that 21 of the protected areas meet the criteria needed for large healthy tiger populations. Further, the study noted that these protected areas have the potential to support between 58 percent and 95 percent of the subcontinent's potential tiger capacity, estimated to be between 3,500 to 6,500 tigers.
In the absence of reliable data to produce a reliable estimate, tiger conservationists say that the big cats may currently number between 1,500 to 4,000 animals in the four countries combined.
The small improvements to increase tiger populations cited in the study include better funding, increasing staff support, restoring tiger habitat, and stepping up enforcement activities that focus on preventing the poaching of tigers and their prey.
"We were happy to find that the most important reserves identified in the study already have made tiger conservation a priority," said the lead author Dr. Jai Ranganathan of the National Center for Ecological Analysis and Synthesis.
The tiger is endangered in all of its natural habitats, a range stretching from India down into Southeast Asia as far as the island of Sumatra, and in the Russian Far East, and is listed as endangered according to both international and U.S. law.
The study is one part of WCS' continuing efforts to conserve the tigers and their wild lands wherever they survive. On a broader scale, WCS is currently working with the Panthera Foundation on an ambitious new program that calls for a 50 percent increase in tiger numbers in key areas over the next decade. This new initiative, called "Tigers Forever," blends a business model with hard science, and has already attracted the attention of venture capitalists who have pledged an initial $10 million to go to specific projects to support the initiative.
Unlike earlier efforts to set tiger conservation targets that were mostly based on land cover maps, this study for the first time incorporated field data on tiger densities derived from the pioneering camera trapping work of WCS researcher Dr. Ullas Karanth and colleagues. The study also assessed the impact of the landscape matrix surrounding the reserves using tiger population models based on measured and expected tiger densities.
The researchers found that landscapes surrounding protected areas play a significant role in the ability of those reserves to support tigers. The 21 areas most capable of supporting large numbers of tigers are concentrated in a few regions in central India, and the Indian borders with Nepal and Bhutan. Eighteen of the protected areas currently contain tiger populations.
The remaining 129 protected areas do not have the potential to sustain high numbers of tigers, but nonetheless these reserves could be capable of containing tigers over the long term if the landscape surrounding the reserves are better managed to reduce negative impacts.
Though no truly accurate global numbers exist, conservationists guess that 5,000 tigers remain in the wild. About 150 years ago, 100,000 tigers may have roamed throughout much of Asia according to some guesses.
The study appears in the most recent edition of the journal Biological Conservation.
Adapted from materials provided by Wildlife Conservation Society.

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