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 They also used climate change records that paleoclimatologists reconstructed by consulting historical documents and examining indicators of temperature change like tree rings, as well as oxygen isotopes in ice cores and coral skeletons.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.

Fausto Intilla

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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

www.oloscience.com

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

www.oloscience.com

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

www.oloscience.com

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.

Fausto Intilla

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