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A new model for understanding biodiversity

2011-11-25T16:07:00.001+05:30

Researchers develop a unified theory of ecosystem change by combining spatial modelling and food web analysis

Animals like foxes and raccoons are highly adaptable. They move around and eat everything from insects to eggs. They and other “generalist feeders” like them may also be crucial to sustaining biological diversity, according to a new study published this week in the Proceedings of the National Academy of Sciences (PNAS).

McGill biology researchers have developed a unified, spatially based understanding of biodiversity that takes into account the complex food webs of predators and prey. “Biodiversity exists within a landscape. Predators and prey are continuously on the move as their habitats change – it’s a complex dynamic system,” says lead author Pradeep Pillai, a former doctoral candidate at McGill, now a research associate at the University of Oregon.

Previous theories of biodiversity have either concentrated on the complex network of feeding interactions that connects all species into food webs or have focused on the way that species are connected in space. “A unified theory of ecological diversity requires understanding how species interact both in space and time, and this is what is different about our work,” explains co-author Michel Loreau, who holds the Canada Research Chair in Theoretical Community and Ecosystem Ecology.

What they discovered was that a “branching network” maintained by generalist species, like foxes or coyotes, that are able to move around and prey on different species in different locations, have an important role in promoting complex food webs and thereby in maintaining biodiversity. The researchers concluded that these generalist species have the advantage of being able to find prey no matter where they are as they move from one place to another, and this sustains the network.

This theory also lays a foundation for understanding the effects human activities – like deforestation – are likely to have not simply on a single species but on whole food webs. The researchers show how food webs are eroded by species extinction when disturbed by habitat destruction. “The theory is useful because it helps us understand how biodiversity is maintained, but also the impacts humans have when they disrupt ecological networks by destroying and fragmenting habitat,” concludes co-author Andrew Gonzalez, Canada Research Chair in Biodiversity Science and Director of the Quebec Centre for Biodiversity Science.

This research was funded by the Natural Sciences and Engineering Research Council and the Fonds québécois de la recherche sur la nature et les technologies.

UN's latest global biodiversity outlook calls for swift action

2010-05-23T13:46:00.000+05:30

Natural systems that support economies, lives and livelihoods across the planet are at risk of rapid degradation and collapse unless there is swift, radical and creative action to conserve and sustainably use the variety of life on Earth.This is one principal conclusion of a major new assessment of the current state of biodiversity and the implications of its continued loss for human well-being.

The third edition of Global Biodiversity Outlook (GBO-3), produced by the Convention on Biological Diversity (CBD), confirms that the world has failed to meet its target to achieve a significant reduction in the rate of biodiversity loss by 2010.

The report is based on scientific assessments, national reports submitted by governments and a study on future scenarios for biodiversity. Subject to an extensive independent scientific review process, the publication of GBO-3 is one of the principal milestones of the UN's International Year of Biodiversity.
The Outlook will be a key input into discussions by world leaders and Heads of State at a special high level segment of the United Nations General Assembly on 22 September. Its conclusions will also be central to the negotiations by world governments at the Nagoya Biodiversity Summit in October.

The Outlook warns that massive further loss of biodiversity is becoming increasingly likely, and with it, a severe reduction of many essential services to human societies as several "tipping points" are approached, in which ecosystems shift to alternative, less productive states from which it may be difficult or impossible to recover.

Potential tipping points analyzed for GBO-3 include:

The dieback of large areas of the Amazon forest, due to the interactions of climate change, deforestation and fires, with consequences for the global climate, regional rainfall and widespread species extinctions.
The shift of many freshwater lakes and other inland water bodies to eutrophic or algae-dominated states, caused by the buildup of nutrients and leading to widespread fish kills and loss of recreational amenities.
Multiple collapses of coral reef ecosystems, due to a combination of ocean acidification, warmer water leading to bleaching, overfishing and nutrient pollution; and threatening the livelihoods of hundreds of millions of species directly dependent on coral reef resources.

The Outlook argues, however, that such outcomes are avoidable if effective and coordinated action is taken to reduce the multiple pressures being imposed on biodiversity. For example, urgent action is needed to reduce land-based pollution and destructive fishing practices that weaken coral reefs, and make them more vulnerable to the impacts of climate change and ocean acidification.
The document notes that the linked challenges of biodiversity loss and climate change must be addressed by policymakers with equal priority and in close co-ordination, if the most severe impacts of each are to be avoided. Conserving biodiversity and the ecosystems it underpins can help to store more carbon, reducing further build-up of greenhouse gases; and people will be better able to adapt to unavoidable climate change if ecosystems are made more resilient with the easing of other pressures.

The Outlook outlines a possible new strategy for reducing biodiversity loss, learning the lessons from the failure to meet the 2010 target. It includes addressing the underlying causes or indirect drivers of biodiversity loss, such as patterns of consumption, the impacts of increased trade and demographic change. Ending harmful subsidies would also be an important step.
GBO-3 concludes that we can no longer see the continued loss of biodiversity as an issue separate from the core concerns of society. Realizing objectives such as tackling poverty and improving the health, wealth and security of present and future generations will be greatly strengthened if we finally give biodiversity the priority it deserves.
The Outlook points out that for a fraction of the money summoned up instantly by the world's governments in 2008-9 to avoid economic meltdown, we can avoid a much more serious and fundamental breakdown in the Earth's life support systems.

In his foreword to GBO-3, United Nations Secretary-General Ban Ki-moon writes: "To tackle the root causes of biodiversity loss, we must give it higher priority in all areas of decision-making and in all economic sectors."
"As this third Global Biodiversity Outlook makes clear, conserving biodiversity cannot be an afterthought once other objectives are addressed - it is the foundation on which many of these objectives are built."
"We need a new vision for biological diversity for a healthy planet and a sustainable future for humankind."

UN Under-Secretary-General and Executive Director of the United Nations Environment Programme, Achim Steiner, adds that there have been key economic reasons why the 2010 biodiversity targets were not met.
"Many economies remain blind to the huge value of the diversity of animals, plants and other life-forms and their role in healthy and functioning ecosystems from forests and freshwaters to soils, oceans and even the atmosphere," observes Mr. Steiner.
"Many countries are beginning to factor natural capital into some areas of economic and social life with important returns, but this needs rapid and sustained scaling-up."

"Humanity has fabricated the illusion that somehow we can get by without biodiversity or that it is somehow peripheral to our contemporary world: the truth is we need it more than ever on a planet of six billion heading to over nine billion people by 2050."
The Executive Secretary of the Convention on Biological Diversity, Ahmed Djoghlaf, says: "The news is not good. We continue to lose biodiversity at a rate never before seen in history - extinction rates may be up to 1,000 times higher than the historical background rate."

"The assessment of the state of the world's biodiversity in 2010, as contained in GBO-3 based on the latest indicators, over 110 national reports submitted to the Convention Secretariat, and scenarios for the 21st Century should serve as a wake-up call for humanity. Business as usual is no longer an option if we are to avoid irreversible damage to the life-support systems of our planet."
"The Convention's new Strategic Plan, to be adopted at the 2010 Nagoya Biodiversity Summit must tackle the underlying causes of biodiversity loss. The linked challenges of biodiversity loss and climate change must be addressed with equal priority and close cooperation. Joint action is needed to implement the Conventions on Biodiversity, Climate Change and to Combat Desertification - the three conventions born of the 1992 Rio Conference. The Rio+20 Summit offers an opportunity to adopt a workplan to achieve this."
KEY FINDINGS:

Biodiversity in 2010

GBO-3 uses multiple lines of evidence to demonstrate that the target set by world governments in 2002, "to achieve by 2010 a significant reduction of the current rate of biodiversity loss at the global, regional and national level", has not been met. Based on a special analysis of biodiversity indicators carried out by a panel of scientists, as well as peer-reviewed scientific literature and reports from national governments to the CBD, key findings include:

None of the twenty-one subsidiary targets accompanying the overall 2010 biodiversity target can be said definitively to have been achieved globally, although some have been partially or locally achieved. Ten of fifteen headline indicators developed by the CBD show trends unfavorable for biodiversity.
No government claims to have completely met the 2010 biodiversity target at the national level, and around one-fifth state explicitly that it has not been met.
Species that have been assessed for extinction risk are on average moving closer to extinction, with amphibians facing the greatest risk and coral species deteriorating most rapidly.
The abundance of vertebrate species, based on assessed populations, fell by nearly one-third on average between 1970 and 2006, and continues to fall globally, with especially severe declines in the tropics and among freshwater species.
Natural habitats in most parts of the world continue to decline in extent and integrity, notably freshwater wetlands, sea-ice habitats, salt marshes, coral reefs, seagrass beds and shellfish reefs; although there has been significant progress in slowing the rate of loss of tropical forests and mangroves, in some regions.
Crop and livestock genetic diversity continues to decline in agricultural systems. For example, more than sixty breeds of livestock are reported to have become extinct since 2000.
The five principal pressures directly driving biodiversity loss (habitat change, over-exploitation, pollution, invasive alien species and climate change) are either constant or increasing in intensity.
There has been significant progress in the increase of protected areas both on land and in coastal waters. However, 44% of terrestrial eco-regions (areas with a large proportion of shared species and habitat types), and 82% of marine eco-regions, fall below the target of 10% protection. The majority of sites judged to be of special importance to biodiversity also fall outside protected areas.

Biodiversity Futures for the 21st Century

Scientists from a wide range of disciplines came together as part of the preparation of GBO-3 to identify possible future outcomes for biodiversity during the current century, based on observed trends, models and experiments. Their principal conclusions include:

Projections of the impact of global change on biodiversity show continuing and often accelerating species extinctions, loss of natural habitat, and changes in the distribution and abundance of species, species groups and biomes over the 21st Century.
There is a high risk of dramatic biodiversity loss and accompanying degradation of a broad range of ecosystem services if the Earth system is pushed beyond certain thresholds or tipping points.

Earlier assessments have underestimated the potential severity of biodiversity loss based on plausible scenarios, because the impacts of passing tipping points or thresholds of ecosystem change have not previously been taken into account.
There are greater opportunities than identified in earlier assessments to address the biodiversity crisis while contributing to other social objectives; for example, by reducing the scale of climate change without large-scale deployment of biofuels and accompanying loss of natural habitats.
Biodiversity and ecosystem changes could be prevented, significantly reduced or even reversed if strong action is applied urgently, comprehensively and appropriately, at international, national and local levels.

Towards a strategy for reducing biodiversity loss

GBO-3 sets out a number of elements that could be considered in a future strategy to reduce biodiversity loss, and avoid the worst impacts of the scenarios analyzed in the Outlook. It is likely to form the basis of discussion of the strategic plan currently being considered for the next decade of the Convention on Biological Diversity, and due to be agreed at the 10th meeting of the Conference of Parties to the CBD in Nagoya, Japan, in October 2010. The elements include:

Continued and intensified direct intervention to reduce loss of biodiversity, for example through expanding and strengthening protected areas, and programmes targeted at vulnerable species and habitats;
Continued and intensified measures to reduce the direct pressures on biodiversity, such as preventing nutrient pollution, cutting off the pathways for introduction alien invasive species, and introducing more sustainable practices in fisheries, forestry and agriculture;
Much greater efficiency in the use of land, energy, fresh water and materials to meet growing demand from a rising and more prosperous population;

Use of market incentives, and avoidance of perverse subsidies, to minimize unsustainable resource use and wasteful consumption;
Strategic planning to reconcile development with the conservation of biodiversity and the maintenance of the multiple services provided by the ecosystems it underpins;
Restoration of ecosystems to safeguard essential services to human societies, while recognizing that protecting existing ecosystems is generally much more cost-effective than allowing them to degrade in the first place;
Ensuring that the benefits arising from the use of and access to genetic resources and associated traditional knowledge, for example through the development of drugs and cosmetics, are equitably shared with the countries and cultures from which they are obtained;
Communication, education and awareness-raising to ensure that as far as possible, everyone understands the value of biodiversity and what steps they can take to protect it, including through changes in personal consumption and behavior.

Wilder weather exerts a stronger influence on biodiversity than steadily changing conditions

2010-01-20T01:50:00.000+05:30

An increase in the variability of local conditions could do more to harm biodiversity than slower shifts in climate, a new study has found.

Climate scientists predict more frequent storms, droughts, floods and heat waves as the Earth warms. Although extreme weather would seem to challenge ecosystems, the effect of fluctuating conditions on biodiversity actually could go either way. Species able to tolerate only a narrow range of temperatures, for example, may be eliminated, but instability in the environment can also prevent dominant species from squeezing out competitors.

"Imagine species that have different optimal temperatures for growth. In a fluctuating world, neither can get the upper hand and the two coexist," said Jonathan Shurin, an ecologist at the University of California, San Diego who led the project. Ecologists have observed similar positive effects on populations of organisms as different as herbacious plants, desert rodents, and microscopic animals called zooplankton.

Now a study of zooplankton found in dozens of freshwater lakes over decades of time has revealed both effects. Shurin and colleagues found fewer species in lakes with the most variable water chemistry. But lakes with the greatest temperature variations harbored a greater variety of zooplankton, they report in the journal Ecology Letters January 21.

Their study considered data from nine separate long-term ecological studies that included a total of 53 lakes in North America and Europe. In addition to sampling zooplankton, scientists had also taken physical measurements repeatedly each season for periods ranging from 3 to 44 years.

From these data, they calculated the variability of 10 physical properties, including pH and the levels of nutrients such as organic carbon, phosphorous and nitrogen. Temperatures and the amount of oxygen dissolved in the water at both the surface and bottom of each lake were also included. The authors also teased apart variation based on the pace of change with year-to-year changes considered separately from changes that occurred from season-to-season or on more rapid timescales.

Zooplankton populations respond quickly to changes because they reproduces so fast. "In a summer, you're sampling dozens of generations," Shurin said. "For mammals or annual plants, you would have to watch for hundreds or thousands of years to see the same population turnover."

At every time scale the pattern held: Ecologists found fewer species of zooplankton in lakes with fluctuating water chemistry and greater numbers of species in those with varying temperatures. The authors noted that the temperature variations they observed remained within normal ranges for these lakes. But some chemical measures, particularly pH and levels of phosphorous, strayed beyond normal limits due to pollution and acid rain.

Environmental variability through time could either promote or reduce biodiversity depending on the pace and range of fluctuations, the authors suggested.

"It may depend on the predictability of the environment. If you have a lot of violent changes through time, species may not be able to program their life cycles to be active when conditions are right. They need the ability to read the cues, to hatch out at the right time," Shurin said. "If the environment is very unpredictable, that may be bad for diversity, because many species just won't be able to match their lifecycles to that."

2010: International Year of Biodiversity

2010-01-11T18:33:00.000+05:30

In a bid to curb the unprecedented loss of the world's species due to human activity - at a rate some experts put at 1,000 times the natural progression - the United Nations is marking 2010 as the International Year of Biodiversity, with a slew of events highlighting the vital role the phenomenon plays in maintaining the life support system on Planet Earth.

"Humans are part of nature's rich diversity and have the power to protect or destroy it," the Secretariat of the Convention on Biological Diversity (CBD), which is hosted by the UN Environment Programme (UNEP), said in summarizing the Year's main message, with its focus on raising awareness to generate public pressure for action by the world's decision makers.

"Biodiversity, the variety of life on Earth, is essential to sustaining the living networks and systems that provide us all with health, wealth, food, fuel and the vital services our lives depend on. Human activity is causing the diversity of life on Earth to be lost at a greatly accelerated rate.

These losses are irreversible, impoverish us all and damage the life support systems we rely on every day. But we can prevent them."

The Convention - which opened for signature at the Earth Summit in Rio de Janeiro in 1992, entered into force at the end of 1993 and now has 193 Parties - is based on the premise that the world's diverse ecosystems purify the air and the water that are the basis of life, stabilize and moderate the Earth's climate, renew soil fertility, cycle nutrients and pollinate plants.

As a former UNEP Executive Director, Klaus Töpfer, put it: "If any part of the web suffers breaks down, the future of life on the planet will be at risk." That is why the UN General Assembly proclaimed 2010 as the International Year of Biodiversity.

Although initial celebrations began in November under the slogan "Biodiversity is life, biodiversity is our life," the official launch will take place in Berlin on 11 January. This will be followed on 21 and 22 January by the first major event of the Year, a high-profile meeting at the Paris headquarters of the UN Educational, Scientific and Cultural Organization (UNESCO), which is expected to bring together heads of state, royalty and their representatives.

A host of other events - meetings, symposia, multi-media exhibitions - will follow throughout the year in venues around world, from Trondheim, Norway, to Delhi, India, from Doha, Qatar, to Cartagena, Colombia, and from Shanghai, China, to Nairobi, Kenya, culminating in a high-level meeting at UN Headquarters in New York at the start of the General Assembly's 65th annual General Debate in September and an official closing in Kanazawa, Japan, in December.

"A wide variety of environmental goods and services that we take for granted are under threat, with profound and damaging consequences for ecosystems, economies and livelihoods," Secretary-General Ban Ki-moon said in November at the start of the pre-celebrations.

"In this International Year, we must counter the perception that people are disconnected from our natural environment. We must increase understanding of the implications of losing biodiversity. In 2010, I call on every country and each citizen of our planet to engage in a global alliance to protect life on Earth."

The Montreal-based CBD Secretariat likewise stresses the urgency in raising public awareness of the importance of biodiversity and the consequences of its loss.

"The goal for raising awareness of these issues is to generate public pressure for action by decision makers, and to create the conditions for governments, individuals and other important sectors, to be encouraged to implement the Convention and to engage with other international and national institutions, towards achieving the goals of the Convention."

The Convention covers all ecosystems, species, and genetic resources, linking traditional conservation efforts to the economic goal of using biological resources sustainably, setting principles for the fair and equitable sharing of the benefits from the use of genetic resources, notably for commercial use and covering the rapidly expanding field of biotechnology, and addressing technology development and transfer, benefit-sharing and biosafety.

While recognizing that ecosystems, species and genes must be used for the benefit of humans, the Convention stipulates that this must be done in a way and at a rate that does not lead to the long-term decline of diversity.

It offers decision-makers guidance based on the precautionary principle that where there is a threat of significant reduction or loss of biological diversity, lack of full scientific certainty should not be used as a reason for postponing measures to avoid or minimize such a threat. It acknowledges that substantial investment is required to conserve diversity, but argues that conservation will bring significant environmental, economic and social benefits in return.

Looking at the economic costs of action or inaction, a recent UN-backed Economics of Ecosystems and Biodiversity (TEEB) study estimated loss of natural capital due to deforestation and degradation at between $2 trillion and $4.5 trillion every year - "a staggering economic cost of taking nature for granted.

"It is estimated that for an annual investment of $45 billion into protected areas alone, we could secure the delivery of ecosystem services worth some $5 trillion a year," it said. "When compared to current financial losses on the markets, this is not a big price to pay. Sound ecosystem and biodiversity management, and the inclusion of Natural Capital in governmental and business accounting can start to redress inaction and reduce the cost of future losses."

Suit Filed to Stop Hawaii longline fishery from tripling sea turtle kill

2009-12-23T15:48:00.000+05:30

Deadly Hooks Also Snag Whales, Seabirds, and Sharks

Conservation groups Turtle Island Restoration Network, the Center for Biological Diversity, and KAHEA, all represented by Earthjustice, filed a lawsuit in federal district court in Honolulu challenging the National Marine Fisheries Service’s issuance of a rule that removes all limits on effort in the Hawaii-based longline swordfish fishery and allows the fleet to catch nearly three times as many loggerhead sea turtles as was previously permitted.

The new rule conflicts with the Fisheries Service’s own assessment that the North Pacific loggerhead sea turtle is in danger of extinction. That report, released only four months ago, noted that incidental capture in longline fisheries is a primary threat to the species’ continued existence.

The new regulations increase allowable capture of threatened North Pacific loggerhead sea turtles from 17 per year to 46 per year. The rule continues to allow the capture of 16 endangered Pacific leatherbacks each year. The Hawaii longline swordfish fishery also catches, injures, and kills false killer whales, albatross, and blue sharks.

"The sea turtles are swimming toward extinction, yet this plan seems intent on continuing the same old fishery policies hastening their demise," said Teri Shore, program director of Turtle Island Restoration Network. “We are disappointed, given Obama’s new directives to protect the oceans.” The president’s Ocean Task Force recently held hearings around the country to develop a national ocean policy, including one in Hawaii last September.

Swordfish longline vessels trail up to 60 miles of fishing line suspended in the water with floats, with as many as 1,000 baited hooks deployed at regular intervals. Sea turtles become hooked while trying to take bait or entangled while swimming through the nearly invisible lines. These encounters can drown the turtles or leave them with serious wounds.

“The Fisheries Service has admitted that loggerhead and leatherback sea turtles in the Pacific face a significant risk of extinction unless we reduce the number of turtles killed by commercial fisheries,” said Andrea Treece, an attorney with the Center for Biological Diversity. “Unfortunately, rather than take action to improve protection of sea turtles, the agency is proposing measures that would actually increase the number of turtles killed.”

“The law requires the Fisheries Service to minimize harm to sea turtles, and prohibits harm to albatross, both of which are being driven to extinction mainly because of irresponsible fishing practices,” said Paul Achitoff, an attorney with Earthjustice in Hawaii. “The agency is once again disregarding these laws in favor of maximizing swordfish catches and pandering to WESPAC’s insatiable appetite for short-term profits.”

“Allowing longline fishing for swordfish in the rich waters off Hawaii is like allowing landmines to be used for deer hunting in national parks,” said Marti Townsend, program director of KAHEA: The Hawaiian-Environmental Alliance. “You may catch what you are after, but the collateral damage to other wildlife is simply unacceptable.”

The litigation is being supported by the Snorkel Bob Foundation of Hawaii, which sponsors results-oriented work that prevents incidental killing of marine species.

Final moments of bee landing tactics revealed

2009-12-23T11:56:00.000+05:30

Landing is tricky: hit the ground too fast and you will crash and burn; too slow and you may stall and fall. Bees manage their approach by monitoring the speed of images moving across their eyes. By slowing so that the speed of the looming landing pad's image on the retina remains constant, bees manage to control their approach.

But what happens in the final few moments before touch down? And how do bees adapt to landing on surfaces ranging from the horizontal to upside-down ceilings? Flies land on a ceiling by simply grabbing hold with their front legs and somersaulting up as they zip along, but a bee's approach is more sedate.

Mandyam Srinivasan, an electrical engineer from the Queensland Brain Institute, The University of Queensland and the Australian Research Council's Vision Centre, knew that bees must be doing something different from daredevil flies. Curious to know more about bee landing strategies Srinivasan teamed up with Carla Evangelista, Peter Kraft, and Judith Reinhard from the University of Queensland, and Marie Dacke, visiting from Lund University.

The team used a high-speed camera to film the instant of touch down on surfaces at various inclinations and publish their discoveries about bee landing tactics in The Journal of Experimental Biology.

First the scientists built a bee-landing platform that could be inclined at any angle from horizontal to inverted (like a ceiling), then they trained bees to land on it and began filming. Having collected movies of the bees landing on surfaces ranging from 0deg. to 180deg., and every 10deg. inclination between, Evangelista began the painstaking task of manually analysing the bees landing strategies, and saw that the bees' approach could be broken down into 3 phases.

Initially the bees approached from almost any direction and at any speed, however, as they got closer to the platforms, they slowed dramatically, almost hovering, until they were 16mm from the platform when they ground to a complete halt, hovering for anything ranging from 50ms to over 140ms. When the surface was horizontal or inclined slightly, the bees' hind legs were almost within touching distance of the surface, so it was simply a matter of the bee gently lowering itself and grabbing hold with its rear feet before lowering the rest of the body.

However, when the insects were landing on surfaces ranging from vertical to 'ceilings', their antennae were closest to the surface during the hover phase. The team saw that the antennae grazed the surface and this contact triggered the bees to reach up with the front legs, grasp hold of the surface and then slowly heave their middle and hind legs up too. "We had not expected the antennae to play a role and the fact that there is a mechanical aspect of this is something that we hadn't thought about," admits Srinivasan.

Looking at the antennae's positions, the team realised that in the final stages as the insects approached inverted surfaces, they held their antennae roughly perpendicular to the surface. "The bee is able to estimate the slope of the surface to orient correctly the antennae, so it is using its visual system," explains Srinivasan. But this is surprising, because the insects are almost completely stationary while hovering and unable to use image movement across the eye to estimate distances. Srinivasan suspects that the bees could be using stereovision over such a short distance, and is keen to test the idea.

Finally the team realised that bees are almost tailor made to land on surfaces inclined at angles of 60deg. to the horizontal. "When bees are flying fast their bodies are horizontal, but when they are flying slowly or hovering their abdomen tilts down so that the tips of the legs and antennae lie in a plane that makes an angle of 60 degrees," explains Srinivasan. So the legs and antennae all touch down simultaneously on surfaces inclined at 60deg. "It seems like they are adapted to land on surfaces tilted to 60deg. and we are keen to find out whether many flowers have this natural tilt," says Srinivasan.

Srinivasan is optimistic that he will eventually be able to use his discoveries in the design of novel flight control systems.

Spider web glue spins society toward new biobased adhesives

2009-12-22T12:24:00.000+05:30

Photo: Randolph Femmer, National Biological Information InfrastructureWith would-be goblins and ghosts set to drape those huge fake spider webs over doorways and trees for Halloween, scientists in Wyoming are reporting on a long-standing mystery about real spider webs: It is the secret of spider web glue.

The findings are an advance toward a new generation of biobased adhesives and glues – "green" glues that replace existing petroleum-based products for a range of uses. A report on the study was published in ACS' Biomacromolecules, a monthly journal.

Omer Choresh and colleagues note that much research has been done on spider web silk, which rivals steel in its strength. However, scientists know comparatively little about web glue, which coats the silk threads and is among the world's strongest biological glues. Past studies revealed that spiders make web glue from glycoproteins, or proteins bits of sugar attached.

The scientists analysed web glue from the golden orb weaving spider, noted for spinning intricate webs. They identified two new glycoproteins in the glue and showed that domains of these proteins were produced from opposite strands of the same DNA. "Once the cloned genes are over expressed in systems such as insect or bacterial cell cultures, large-scale production of the glycoprotein can be used to develop a new biobased glue for a variety of purposes," the report notes.

Shedding light on microscopic flower petal ridges

2009-12-22T12:14:00.000+05:30

Scanning electron microscope view of plant cell nanoridges. Photo: John OhlroggeMicroscopic ridges contouring the surface of flower petals might play a role in flashing that come-hither look pollinating insects can't resist. Michigan State University scientists and colleagues now have figured out how those form.

The result could help researchers learn to enhance plants' pollination success and even could lead to high-grip nanomaterials and "green chemical" feedstocks."Surprisingly, our work on plant surface biochemistry became a birds and bees and flowers story," said John Ohlrogge, MSU University Distinguished Professor of plant biology. "It's a fundamental property of plant flowers, and we've discovered a basis of how these ridges are made."

Known for 75 years, the exact biological function and nature of the flower nanoridges still eludes scientists. They might help pollinating insects grip petals, and retain glistening water droplets that could attract the visitors. Because the ridges' spacing is approximately that of visible and ultraviolet light wavelengths, moreover, some recent research suggests they produce an iridescent shimmer that attracts pollinators.

To start, visiting professor Mike Pollard and former Ohlrogge post-doctoral research associates Fred Beisson and Yonghua Li tapped new genetic information to find a mutated strain of the standard research plant Arabidopsis thaliana – mustard weed. The petals have no such nanoridges because the mutation inhibits production of a polymer that forms the plant cuticle, which separates cell walls from plants' waxy surfaces.

Examining the mutant plants' flowers and comparing them to normal mustard plants under scanning electron microscopes, the researchers found that the ridges form from cutin polyester, not from underlying surfaces as some have speculated. How that occurs – from surface folding or uneven synthesis of cutin polymer across the cell wall, for example, has yet to be learned.

But the research will open doors to further research based on cuticular nanostructures, the researchers noted in a recent edition of the journal Proceedings of the National Academy of Sciences.

"That could include production of polyesters or related basic chemicals by genetically manipulating plants or microbes" said Beisson, now at Aix Marseille Université in Saint-Paul-lez-Durance, France.

Seeing how evolutionary mechanisms yield biological diversity

2009-12-22T12:06:00.000+05:30

An international team of scientists has discovered how changes in both gene expression and gene sequence led to the diversity of visual systems in African cichlid fish.

In research published in the December 21, 2009 issue of the journal PLoS Biology, Assistant Professor Karen Carleton, together with post-doctoral associate Chris Hofmann and graduate student Kelly O'Quin, in the University of Maryland Department of Biology, and collaborators Justin Marshall, University of Queensland; Tom Cronin, University of Maryland, Baltimore County (UMBC); and Ole Seehausen, University of Bern; describe how over 60 species of cichlid fish from Lake Malawi and Lake Victoria have adapted their visual sensitivity in response to specific ecological factors, including what they eat and the clarity of the water in which they swim.

Evolutionary biologists seek to understand the mechanisms behind genetic changes that have led to the vast diversity of life on Earth. There are two important molecular mechanisms that contribute to organismal diversity - changes to the sequence of genes, and changes in the way genes are expressed, including when, where, and how much of a gene is made. This study was one of the first to look at how both gene sequence and gene expression can contribute to the same trait, and showed that they contribute in complementary ways.

"African cichlid fishes are some of the most diverse animals on the planet. Their visual systems differ dramatically in their sensitivity and represent some of the largest differences known in vertebrates," explains Hofmann. "Yet there has been little understanding as to why such diversity exists. Our findings have important implications for understanding both the factors and the mechanisms responsible for generating biodiversity."

Cichlids have several different cone opsin genes that enable them to detect light across the visible and ultraviolet regions of the spectrum. Different species express different subsets of these opsins to create alternate visual systems. The research team found that cichlid fish in the clear waters of Lake Malawi expressed a wide range of opsins, with closely related species differing in whether they used the shorter wavelength or longer wavelength gene combinations.

The method of foraging for food was a key factor influencing fish vision. Fish whose diets consist primarily of zooplankton were more likely to have UV sensitivity, which enables them to detect the presence of these small transparent aquatic organisms that absorb ultraviolet light. In contrast, cichlids in the murky waters of Lake Victoria expressed longer wavelength combination of opsin genes, regardless of what they ate.

This long wavelength combination matches the light that is best transmitted through the murky water. A few Lake Victoria fish at clearer sites turned on shorter wavelength genes, suggesting that opsin expression matches the light environment. Therefore opsin gene expression in both lakes is adaptively determined based on important ecological variables.

The authors also examined changes in the genetic sequence of these opsins that fine-tuned visual pigment sensitivity at the short and long-wavelength ends of the spectral range.

"When you get to the extremes of the light spectrum, there is no other gene that can be turned on or off, so the only way to extend the sensitivity is to change the gene structure itself," says O'Quin. Therefore, this study presents a model of sensory evolution in which both molecular genetic mechanisms work in concert.

Previous work by Ole Seehausen, Karen Carleton, Nori Okada and colleagues (Nature, 455, 620-626, 2 October 2008) has demonstrated that colour vision plays a key role in how cichlids recognise different species and choose mates.

"Previously, we showed that changes in opsin gene sequence contributed to generating new species," says Carleton. "The speed with which opsin gene expression changes suggests that it might also contribute to creating the incredible diversity of cichlid fishes."

The authors are extending their work to other African Great Lakes and even to coral reef fishes, to better understand how biodiversity is formed.

Loud and lazy but didn't chew gum: Ancient koalas

2009-12-21T21:50:00.001+05:30

Photo:Arnaud Gaillard/WikimediaSkull fragments of prehistoric koalas from the Riversleigh rainforests of millions of year ago suggest they shared the modern koala's "lazy" lifestyle and ability to produce loud "bellowing" calls to attract mates and provide warnings about predators.

However, the new findings published as the featured cover article in the current issue of the Journal of Vertebrate Paleontology suggest that the two species of koalas from the Miocene (24 to five million years ago) did not share the uniquely specialized eucalyptus leaf diet of the modern koala (Phascolarctos cinereus).

The shift to a wholly eucalyptus diet by modern koalas was an adaptation that probably came later as Australia drifted north, causing its rainforests to retreat and Eucalypts to become the dominant tree of most Australian forests and woodlands.

Modern koalas – the sole living member of the diprotodontian marsupial family Phascolarctidae –are among the largest of all arboreal leaf-eaters. To attain this remarkable condition on a diet of eucalyptus leaves, a notoriously poor and somewhat toxic food source, the tree-dwelling marsupials developed unique anatomical and physiological adaptations including specialized chewing and digestive anatomies and a highly sedentary lifestyle. The dramatic differences between the skulls of extinct and modern koalas, especially in the facial region, are probably related to the change to a tougher diet of eucalyptus leaves.

Researchers from the University of New South Wales and the CSIRO have drawn these conclusions after making dozens of detailed anatomical comparisons between the brush-tailed possum, the modern koala and the two fossil species (Litokoala kutjamarpensis and Nimiokoala greystanesi).

The fossil species were unearthed from the Riversleigh World Heritage site in Queensland, Australia. The comparisons reveal similarities in the back of the skull between the modern and fossil koalas, but substantial differences in their teeth, palate and jaws.

Koalas are most closely related among living marsupials to wombats but the two species diverged some 30-40 million years ago. Among fossil koalas there are 18 named species representing five genera spanning the period from the late Oligocene (37 million years ago) to the present.

However, they are generally scarce in the fossil record and most species are only known from a few isolated teeth or jaw fragments. Therefore, it has been difficult to develop an accurate picture of their behaviour, diet and evolution.

The researchers believe that the prehistoric koalas also shared with their modern cousins the ability to produce loud "bellows" based on similar large bony prominences – the auditory bullae – that enclose structures in the middle and inner ear. However the auditory bullae of the extinct Nimiokoala and Litokoala species are not as exaggerated as in the modern koala, according to team member UNSW Professor Mike Archer.

"Modern koalas are extremely sedentary and vocal animals," says Archer, who is perhaps best known for leading research into the extraordinary Riversleigh fossil deposits in Queensland, which led to the site being listed on the World Heritage Register.

"They produce low frequency vocalisations that pass through vegetation and can be heard up to 800 metres away – far exceeding the home range limits of male koalas. The fossil koalas share similar large bony ear structures to the modern koala and would have been well adapted to detecting vocalisations in the rainforest environment of Riversleigh in the Miocene era."

"In order to accommodate both the mechanical demands of their new diet, as well as maintaining their auditory sophistication, the koala underwent substantial changes to its cranial anatomy, in particular that of the facial skeleton," says Dr Julien Louys of UNSW's School of Biological, Earth and Environmental Sciences. "The unique cranial configuration of the modern koala is therefore the result of accommodating their masticatory adaptations without compromising their auditory system."

How the daisy got its spots

2009-12-18T21:58:00.001+05:30

Photo:Meredith Murphy ThomasDevelopment and morphology of insect-mimicking spots on the flower petals of a South African beetle daisy

Dark spots on flower petals are common across many angiosperm plant families and occur on flowers such as some lilies, orchids, and daisies. Much research has been done on the physiological and behavioural mechanisms for how these spots attract pollinators. But have you ever wondered what these spots are composed of, how they develop, or how they only appear on some but not all of the ray florets?

Dr. Meredith Thomas from the University of Cambridge and associates from England and South Africa were interested in exploring these questions and published their findings in the December issue of the American Journal of Botany.

They focused on the South African endemic beetle daisy Gorteria diffusa (Asteraceae), which has a unique, raised, dark spot at the base of some of its ray florets.

"I find this plant/pollinator system very exciting to study because of the amazing morphological variation in the flowers between populations," Thomas said. "The spots on the flowers mimic the plant's pollinator, a small fly, which is attracted to the plant because of the spots. The plant is dependent on the pollinator for reproductive success, so it's incredibly important that the plant attracts the flies.

"What we found surprising," Thomas continued, "was how complex the petal spots are in a few populations, when other populations seem to get by with a very simple spot or even no petal spot at all."

By peeling away layers of the tissues that make up the spots on mature ray florets and examining them under a simple dissecting scope, Thomas and associates found that the spots of G. diffusa are more complex than most. These spots are composed of three different types of specialised epidermal cells: the central highlight cells that reflect UV and lack pigment; the interior cells that are shorter, rounder, variously pigmented, and raised above the highlight cells; and, surrounding the spot, a circle of multi-cellular papillae that are swollen, shiny, and filled with anthocyanin. Moreover, each spot spans four congenitally fused petal lobes, meaning that each lobe contained only part of the spot (and only some cell types) in its genetic makeup.

So what attracts the pollinators? Because there is a lot of spot variation in this species, the authors hypothesise that the elements that are found in common among the various populations, such as the presence of anthocyanin pigment or UV reflectivity, might do the trick.

The authors also wanted to know how only a subset of the floral rays develops a spot. Using scanning electron microscopy the authors looked at how the spot developed, or its ontogeny, over time. They found that only the first few ray florets that develop contain the spots, whereas the rest do not.

Thomas noted that "the plant has evolved a very clever way of distributing the pollinator-mimicking spots around the inflorescence so that they appear random, as if a few flies had just landed on the inflorescence, when in fact the position of the spots is mathematically pre-determined according to the plant's phyllotaxy [or the order and location in which new floral organs are initiated]."

The authors hypothesise that the genes that control the appearance of the spot are turned on initially and then fade with time, such that only the first, and oldest, rays to develop have the spots. Thus, the development of the spots is complex not only at the cellular level, but at the organismal level as well.

"What we now plan to investigate," concludes Thomas, "is whether the development of this adaptive floral trait is regulated by a similarly complex genetic regulatory pathway, or if this plant has simply co-opted and modified a pathway commonly used in plants to produce other types of specialised surface structures, like hairs."

New report underlines multiple benefits, new challenges to biodiversity-rich sites

2009-12-17T12:23:00.000+05:30

Deforestation in the Usambara Mountains in Lushoto District, Tanga Region, Tanzania.Photo:Mohsin S. Karmali/WikimediaAn agreement in Copenhagen to fund reduced emissions from deforestation may generate multiple environmental and economic benefits if investments simultaneously target sites that are both carbon and biodiversity-rich.

But the new report, published in the journal Conservation Letters, also warns of challenges in countries such as Brazil and parts of East Africa unless safeguards are followed. This is because funding Reduced Emissions from Deforestation and forest Degradation (REDD) might also displace and intensify activities such as agriculture in lower carbon but equally biodiversity-rich locales. Such areas include parts of East Africa and Brazil.

The study has involved a wide range of organisations and institutions including: the Centre for Social and Economic Research on the Global Environment at the University of East Anglia (UEA); the UN Environment Programme's World Conservation Monitoring Centre (UNEP-WCMC) in Cambridge; the Institute for Global and Applied Environmental Analysis (GAEA) in Rio de Janeiro; and Stanford University, California.

It is claimed to be the first map-based analysis of the distribution of carbon and biodiversity and indicates that governments face a series of choices on how best to maximise the benefits and minimise the challenges presented by a possible REDD deal at the UN climate convention this week.

The colour maps allow the identification of areas where these double benefits could be highest, which include many of the global biodiversity hotspots.

For example the maps show that the Amazon hosts very high concentrations of both carbon and overall species richness whereas Sumatra and Borneo represent an opportunity to conserve carbon while conserving a high level of threatened species.

If the aim is to conserve high quantities of carbon while also conserving species found nowhere else in the world – so called endemic species – then the island of New Guinea would be one of the top priorities.

The study also identified areas where carbon funding would not solve the problem by itself, but could provide crucial complementary financing to biodiversity initiatives.

Finally it highlights areas that have high value for biodiversity conservation, but are poor or less rich in carbon and could thus be under increased threat if REDD is implemented including the Brazilian Cerrado or the savannahs of the Rift Valley in East Africa.

Bernardo Strassburg of UEA and GAEA and lead author of the study, said: "Overall REDD would have a very positive effect for biodiversity conservation, which makes it a very powerful tool that simultaneously addresses two of the greatest global environmental crises of our age.

"But as these synergies are unevenly distributed, it is crucial on the one hand that they are maximised by taking biodiversity distribution into account when planning and implementing REDD and, on the other, that conservation planning adapts to a post-REDD world where opportunities and challenges would be relocated."

The research supports the collaborative work by the United Nations and the World Bank and others on preparing countries for a possible REDD regime and then scaling up investments in tropically-forested countries.

UNEP, along with the UN Development Programme and the Food and Agricultural Organisation are working in over nine countries including Bolivia, Paraguay, the Democratic Republic of the Congo, Tanzania, Papua New Guinea and Vietnam. The work compliments that of the World Bank under its Forest Carbon Partnership Facility.

UNEP, with funding from the Global Environment Facility and in partnership with a range of organisations and scientists, is also assessing the potential to 'farm' carbon into landscapes and soils.

The work, initially focusing on western Kenya, Niger, Nigeria and China, aims to generate a universal standard so that investors can know how much carbon is being stored under different farming and land management systems.

This may lead to farmers and landowners being paid for the carbon they store improving the economic value of sustainably farmed and managed land and reducing the risks to biodiversity in landscapes that store lower levels of carbon including those identified in the new report.

News of the study comes as the UN climate convention marks its half way point with Forest Day. Lera Miles, a co-author on the study from UNEP-WCMC, said, "This week's UN climate convention talks will decide how quickly resources will be provided to help developing countries to tackle tropical deforestation. Reducing the loss of natural forest is good for many reasons – it helps to slow global warming by reducing carbon emissions, can conserve threatened species and retain the economically-important ecosystem services upon which forest-dependent people as well as whole economies depend."

Soap opera in the marsh: Coots foil nest invaders, reject impostors

2009-12-16T23:31:00.000+05:30

The American coot is a drab, seemingly unremarkable marsh bird common throughout North America. But its reproductive life is full of deception and violence.

According to biologists at the University of California, Santa Cruz, coots have evolved a remarkable set of cognitive abilities to thwart other coots that lay eggs in their neighbors' nests. In 2003, the researchers showed that coots can count their own eggs and reject ones laid in their nests by other coots. Their latest findings, published this week in Nature, show that coot parents can tell the difference between their own chicks and any impostors that manage to hatch in their nest, and they will violently reject most impostor chicks.

The findings are particularly striking because so many birds seem to be unable to recognise the chicks of species such as cowbirds and cuckoos, which always lay their eggs in the nests of other birds. This behaviour is called brood parasitism, and its success has posed a longstanding challenge to evolutionary theorists.

"When you see a little songbird struggling to feed an enormous cowbird chick, you have to wonder why it can't recognise the parasitic chick when it is so obvious to us," said Bruce Lyon, professor of ecology and evolutionary biology at UCSC and coauthor of the paper. "The coot study shows that chick recognition can evolve, even when the chicks are the same species and all look the same to us."

The researchers found that coots learn to recognise their own chicks each year by using the first-hatched chicks as a template to which other chicks are compared. This learning mechanism may explain why it is so hard for chick recognition to evolve among the hosts of cowbirds and cuckoos, said Dai Shizuka, a UCSC graduate student and first author of the paper.

"Cuckoo and cowbird chicks tend to hatch before the host chicks, so their hosts can't use hatching order as a cue for chick recognition," Shizuka said. "As long as recognition has to be learned, you run the risk of learning incorrectly, and that could be the bottleneck."

These findings provide indirect support for a theory proposed by Arnon Lotem of Tel Aviv University, who attributed the absence of chick recognition in most cuckoo hosts to the high cost of mistaken imprinting. By experimentally causing mistaken imprinting in coots, Shizuka and Lyon confirmed that learned chick recognition does have potential costs.

Lotem assumed a classic imprinting mechanism that would occur only once, during the adult bird's first breeding season. Coots, however, seem to "imprint" on their first-hatched chicks each year. Coots reliably imprint on their own chicks because the first-laid eggs are the first to hatch, and parasitic eggs are deposited only in nests that already have eggs in them.

"It's not that coots are exceptionally smart. They just have reliable information that allows them to do what we expect all hosts 'should' be doing to defend themselves against parasitism," Shizuka said.

The common cuckoo and brown-headed cowbird are specialists in brood parasitism, shifting the burden of parental care onto other species rather than building their own nests. In coots, brood parasitism seems to be an optional component of a reproductive strategy based on laying large numbers of eggs. Depositing a few eggs in a neighbour's nest is just another way to increase the number of potential offspring.

The chances of survival in a neighbour's nest may be slim, but coots habitually lay more eggs than are likely to survive, Lyon said. Only in the best of years is there enough food for all of the chicks; in a typical year, about half of the chicks in each brood starve to death, he said. If a parasitic chick survives, another chick in the brood must die, which explains why coots have evolved such strong defences against parasitism.

"We actually set out to study how coots bring their brood size into alignment with the availability of food, and what role hatching order plays in the culling process. But we kept seeing anecdotal evidence in the field that something else was going on," Lyon said. "With the parasitic chicks, they don't just let them starve, they attack them with a viciousness we hadn't seen before."

The researchers got a one-year extension to their grant, funded by the National Science Foundation, to study chick recognition at their study site in British Columbia. The experiment required removing eggs from the nests at the pipping stage (when the chick starts trying to break the shell) and hatching them in incubators. This allowed the researchers to tag the chicks and record which eggs they came from before returning them to the nests in a controlled sequence.

In one set of nests, the parents got their own chicks back on the first day. After that, chicks were returned to the nests in pairs consisting of an unrelated chick and a chick that belonged to the parents. The unrelated chicks were all siblings. In a second set of nests, the first chicks returned were not related to the parents, after which chicks were returned in pairs as in the first set of nests.

In all cases, a chick's chances of survival were highest if it was returned to the nest on the first day or was a sibling of the first chicks. If the first chicks were unrelated to the parents, the parents would favour them and their siblings and drive off their own chicks. "The parents learn the first chicks they start taking care of as their own, and base their decisions about later chicks on that," Shizuka said.

Using first-hatched chicks as the basis for recognition will be adaptive only if there is a low probability of parasitic chicks hatching first, he said. In a search of the scientific literature, Shizuka found two recent examples of birds, both in Australia, that appear to be able to recognise and reject cuckoo chicks. He said he hopes to learn more about those species and find out how they compare to coots.

The researchers also want to find out what cues coot parents use to recognise their chicks. The possibilities include smell, vocal calls, and visual cues such as plumage. "Those are all plausible hypotheses, but we don't know yet," Shizuka said.

Warming climate chills Sonoran Desert's spring flowers

2009-12-16T13:46:00.002+05:30

Researchers from Larry Venable's lab at the University of Arizona have been studying how climate affects the growth of winter annuals since 1982. This picture shows part of the study site, which is at Tumamoc Hill in Tucson, home of UA's Desert Laboratory. Photo: Kathy Gerst.Global warming is giving a boost to Sonoran Desert plants that have an edge during cold weather, according to new research.

Although the overall numbers of winter annuals have declined since 1982, species that germinate and grow better at low temperatures are becoming more common."It's an unexpected result – that global warming has led to an increase in cold-adapted species," said lead author Sarah Kimball, a research associate at the University of Arizona in Tucson. "Because the winter rains are arriving later, they are occurring under colder temperatures."

Climate change is shifting the winter storm track so the Sonoran Desert's winter rains now generally begin in late November or early December, rather than during the balmy days of late October.

Therefore seeds that require winter rains must sprout during the cooler days of December.

"Southern Arizona has been getting hotter and drier for the last 25 or 30 years, and as a result, the desert annuals we've been studying at Tumamoc Hill have been changing," said co-author D. Lawrence Venable, the UA's director of research at Tumamoc Hill.

The researchers focused on the nine most abundant species, which comprise 74 per cent of all winter annuals found at the study area.

The species of winter desert annuals studied are ones Venable calls "the bread and butter flowers that you see everywhere." Some are called "belly flowers" because they are best seen close up, in contrast to the less common, showy desert annuals like poppies and lupines.

The findings are part of a long-term study of winter annuals that Venable, a UA professor of ecology and evolutionary biology, initiated at Tumamoc Hill in 1982.

Kimball, Venable and their colleagues are publishing their paper, "Contemporary Climate Change in the Sonoran Desert Favors Cold-Adapted Species," in an upcoming issue of the journal Global Change Biology. Amy Angert, now at Colorado State University in Fort Collins, Colo., and Travis Huxman of the UA are also co-authors. The National Science Foundation and the Philecology Foundation of Fort Worth, Texas funded the research.

In 1982, Venable began intensive research into the growth of desert annuals in relation to climate by setting up permanent study plots at Tumamoc Hill.

His research team has been continually monitoring the germination, survival and seed production of the winter annuals ever since. The weather station on Tumamoc Hill provides records of local temperatures and precipitation.

Venable now has 72 plots and a team of people to study each plant's life. Team members start collecting the data 10 days after the first winter rain and after every subsequent rain. Even when there are no subsequent rain events, the team still collects the data monthly.

For each plot, a clear sheet of stiff plastic serves as the year's record of the plants' location and life history.

On each visit, a researcher places the plastic sheet on a frame 3 inches above the plot and uses a permanent marker to record the location of each germinating plant on the plastic sheet. As the season progresses, each plant's survival and seed production is marked on the same sheet.

To make sure even the littlest plant is not overlooked, the researchers must hunch over the plot and its plastic sheet.

"We use knee pads,for sure," Kimball said.

In 2007, Kimball reviewed the data and realised that the temperature at which germination occurred had declined steadily since 1982. However, some species had not done as badly as others and she wondered why.

So she turned to Venable's long-term data set to see which aspect of the plants' growth was responsible for the change. She wanted to know whether some species were germinating better or grew better or just made more seeds.

In a previous study, Venable and his colleagues had examined the physiology of the nine species and found that some grow better under cold conditions and are more efficient at using water. Those species are now becoming more common as the changing climate shifts the onset of the winter rains.

"The physiological component was the 'Ah Ha!' thing," Venable said. "The more water-use-efficient species are more adapted for growing under cold conditions."

Some cold-adapted winter annuals that are becoming more common are popcorn flower, or Pectocarya recurvata, and Erodium cicutarium, known more commonly as red filaree or storksbill.

In contrast, species that germinate better when it is warm, such as wooly sunflower, known to scientists as Eriophyllum lanosum, and a species of plantain, Plantago insularis, are becoming less common.

"Even though overall the winter growing season is getting warmer, what's important in this system is that the growing season is initiated at a later date under colder temperatures," Kimball said. "This demonstrates that the response of organisms to climate change can be unexpected."

New bacterial behaviour observed

2009-12-15T23:27:00.000+05:30

PNAS study documents puzzling movement of electricity-producing bacteria near energy sources

Bacteria dance the electric slide, officially named electrokinesis by the USC geobiologists who discovered the phenomenon. Their study, published online in PNAS Early Edition, describes what appears to be an entirely new bacterial behaviour.The metal-metabolising Shewanella oneidensis microbe does not just cling to metal in its environment, as previously thought. Instead, it harvests electrochemical energy obtained upon contact with the metal and swims furiously for a few minutes before landing again.

Electrokinesis is more than a curiosity. Laboratory director and co-author Kenneth Nealson, the Wrigley Professor of Geobiology at USC and discoverer of Shewanella, hopes to boost the power of microbe-based fuel cells enough to produce usable energy.

The discovery of electrokinesis does not achieve that goal directly, but it should help researchers to better tune the complex living engines of microbial fuel cells.

"To optimise the bacteria is far more complicated than to optimise the fuel cell," Nealson said.

Electrokinesis was discovered in 2007 by Nealson's graduate student Howard Harris, an undergraduate at the time.

Nealson had given Harris what seemed an ideal assignment for a double major in cinema and biophysics.

"I had asked him if he would just take some movies of these bacteria doing what they do," Nealson said.

Filming through a microscope is hardly simple, but with the help of co-author and biophysics expert Moh El-Naggar, assistant professor of physics and astronomy at USC, Harris was able to make a computer analysis of a time-lapse sequence of bacteria near metal oxide particles.

"Every time the bacteria were around these particles … there was a great deal of swimming activity," Nealson recalled.

Harris then discovered that bacteria displayed the same behaviour around the electrode of a battery. The swimming stopped when the electrode turned off, suggesting that the activity was electrical in origin.

As is often true with discoveries, this one raises more questions than it answers. Two in particular intrigue the researchers:

Why do the bacteria expend valuable energy swimming around?

How do the bacteria find the metal and return to it? Do they sense it through an electric field or the behavior of other bacteria?

Nealson and his team so far have only educated guesses.

For the first question, Nealson believes that the bacteria may swim away from the metal because they have too many competitors.

Bacteria get energy in two steps: by absorbing dissolved nutrients and then by converting those nutrients into biologically useful forms of energy through respiration, or the loss of electrons to an electron acceptor such as iron or manganese (humans also respire through the loss of electrons to oxygen, one of the most powerful electron acceptors).

"If electrons don't flow, it doesn't matter how much food you have," Nealson said.

However, he added, "in some environments, the food is much more precious than the electron acceptors."

If a metal surface became too crowded for bacteria to absorb nutrients easily, they might want to swim away and come back.

For the second question, Harris and co-author Mandy Ward, assistant professor of research in earth sciences at USC, are planning other experiments to understand exactly how Shewanella find electron acceptors.

They expect the experiments to keep Harris busy through his doctoral thesis.

Protecting unique wild coffee forests in Ethiopia

2009-12-15T15:18:00.000+05:30

Photo:Charlesfres/Flickr/BirdLifeNABU (BirdLife in Germany), in cooperation with the Ethiopian Government and other partners, will run a special project to protect the last natural forests where the world famous 'arabica' coffee is produced. In the last 10 years, almost 43 per cent of these forests have disappeared, as they have been transformed into arable land, causing a huge loss of biodiversity.

"The clearing of tropical forests is a major source of greenhouse gases. Over the past 40 years, 35 per cent of Ethiopian forests have been lost through deforestation. If we do not act now, Ethiopia will lose all its forests by 2020", commented Olaf Tschimpke, NABU's President, during a reception organised by NABU organisations and GTZ (Deutsche Gesellschaft für technische Zusammenarbeit) at the Admiral Hotel in Copenhagen.

Experts estimate that today's remaining forest area, approximately 200,000 hectares, contains about 25 million tonnes of carbon dioxide in soil biomass. It absorbs 600,000 tonnes each year of the harmful greenhouse gas from the atmosphere which would then be sequestered in soil and biomass, by the remaining forest.

The NABU project will provide both the reforestation and restoration of 700 hectares of natural forest and cultivated areas with native wildlife and timber. "Fifteen hundred hectares of fast growing trees will be planted next to the villages, to ensure people will be living in safety. Furthermore, 10,000 wood-saving stoves will be introduced in selected communities", continued Tschimpke.

The reforestation of 10,000 hectares will be jointly managed with the Biosphere Reserve and will strictly follow the principles of sustainable forest management. For years, this type of cooperation has been used in Kafa, helping people feel responsible for their land.

Special tourist infrastructures, such as animal and bird watching towers, outdoor museums and hiking trails will also be built. After receiving special training, local people will be able to guide tourists and explain the effects of climate change and agriculture practices. Thanks to this project, peoples' living standards will significantly increase.

This project will also ensure the conservation of biodiversity in the region, especially of the Arabica coffee, which has almost 5,000 different varieties. It will be a model for other future international projects, combining climate and resources protection with sustainable local development.

The project is funded by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) within the framework of the International Climate Protection Initiative.

When it comes to fish families, the bigger and bossier the better

2009-12-14T23:39:00.000+05:30

Photo:Chrumps/WikimediaIf you are spending the holidays with big Uncle Frank or bossy Aunt Minnie and wondering whether you would be better off with another family, spare a thought for the humble cichlid fish.

A research team from McMaster University and the University of New South Wales has found that among cichlids, a species that lives in groups, members make strategic decisions about their living situation. The results appear in the current issue of Biology Letters.

The helper class of cichlids showed a preference for joining groups of familiar individuals, some likely to be family members. But when given the choice between unfamiliar social groups the helpers chose groups where the members were bigger and bossier.

At the beginning of the experiment, which was conducted in Zambia's Lake Tanganyika, researchers expected that individual cichlids would base their group-living arrangements on whether they could improve their social rank and thereby expedite their attainment of breeding status.

However, when faced with a choice between unfamiliar groups they chose the group that did not enhance their rank but that contained larger group members.

"It seems that cichlids potentially prefer groups of dominant members for reasons of survival due to the increased protection from predation when larger group members are around," says Marian Wong, a post-doctoral fellow in McMaster's Department of Psychology, Neuroscience & Behaviour, and co-author of the study.

In other words, fish – like humans – understand that membership has its rewards.

Tool use in an invertebrate: The coconut-carrying octopus

2009-12-14T16:24:00.002+05:30

Photo:Nick Hobgood/WikimediaScientists once thought of tool use as a defining feature of humans. That's until examples of tool use came in from other primates, along with birds and an array of other mammals. Now, a report in the December 14th issue of Current Biology, a Cell Press publication, adds an octopus to the growing list of tool users.

The veined octopus under study manages a behavioural trick that the researchers call stilt walking. In it, the soft-bodied octopus spreads itself over stacked, upright coconut shell "bowls," makes its eight arms rigid, and raises the whole assembly to amble on eight "stilts" across the seafloor.The only benefit to the octopus's ungainly manoeuvre is to use the shells later as a shelter or lair, and that's what makes it wholly different from a hermit crab using the discarded shell of a snail.

"There is a fundamental difference between picking up a nearby object and putting it over your head as protection versus collecting, arranging, transporting (awkwardly), and assembling portable armour as required," said Mark Norman of the Museum Victoria in Australia.

Julian Finn, also of the Museum Victoria, said the initial discovery was completely serendipitous.

"While I have observed and videoed octopuses hiding in shells many times, I never expected to find an octopus that stacks multiple coconut shells and jogs across the seafloor carrying them," he said.

In recalling the first time that he saw this behaviour, Finn added, "I could tell that the octopus, busy manipulating coconut shells, was up to something, but I never expected it would pick up the stacked shells and run away. It was an extremely comical sight – I have never laughed so hard underwater."

After 500 diver hours spent "under the sea," the researchers observed the behaviour of 20 veined octopuses. On four occasions, individuals travelled over considerable distances – up to 20 meters – while carrying stacked coconut shell halves beneath their body.

"Ultimately, the collection and use of objects by animals is likely to form a continuum stretching from insects to primates, with the definition of tools providing a perpetual opportunity for debate," the researchers concluded. "However, the discovery of this octopus tiptoeing across the sea floor with its prized coconut shells suggests that even marine invertebrates engage in behaviours that we once thought the preserve of humans."

Sucker-footed bats don't use suction after all

2009-12-14T16:04:00.000+05:30

Photo:Brown UniversityIn first-time experiments in the wild, a researcher at Brown University has discovered that a species of bat in Madagascar, Myzopoda aurita, uses wet adhesion to attach itself to surfaces. The finding explains why the bat – unlike almost all others – roosts head-up. It also helps to explain how it differs from a similar head-up roosting species. Results appear in the Biological Journal of the Linnean Society.

There are approximately 1,200 species of bats worldwide. Of that total, only six are known to roost with their heads pointed upward. Investigators did not know why, because they knew next to nothing about one key group.

The sucker-footed bats of Madagascar, Myzopoda aurita, had rarely been seen in the wild and were listed as vulnerable to extinction by the International Union for Conservation of Nature. But several years ago, biologists stumbled upon some colonies in a new-growth forest on the southeastern section of the island, opening the door to studies.

Daniel Riskin, a postdoctoral research associate in ecology and evolutionary biology at Brown University, traveled last summer to Madagascar to study one of the two species of sucker-footed bats with biologist Paul Racey. In first-time experiments in the wild, the pair made a surprising discovery: The bats don't use suction after all. Instead, they use wet adhesion, secreting a fluid, possibly sweat, that enables the pads on the bats' wrists and ankles to attach to surfaces.

While the finding settles the question of how the bats roost, it means science has misnamed the bat. "Myzopoda literally means 'sucker foot,'" Riskin, the paper's lead author, said. "You can't change Latin names, so it's stuck with it."

Riskin used a force plate he had built to determine how Myzopoda clung to surfaces. He placed the sucker-footed bats on the plates, first with evenly spaced holes and then with the holes covered by tape underneath the plate. In both instances, Myzopoda had no problem adhering to the plate, effectively ruling out suction as the adhesive technique. (Had suction been used, the holes would have prevented the bats from establishing a seal on the surface.)

Next, Riskin sought to understand how the bats roost head-up by testing how they detach their limbs from a surface. Holding the bat so it was head up-and in a vertical position, Riskin discovered that he could easily "unpeel" the bats' pads from the surface. He also encountered little resistance when pushing the bat in an upward direction. But when Riskin tried to drag the bat downward (video clip, right), the animal clung doggedly to the vertical surface.

Through further investigation, Riskin figured out the bats detach themselves from their roosting position by using tendons in their wrists and ankles to decrease the pads' surface area of attachment. This explains why video footage shows the bats' pads peeling off the surface when they begin walking. It also explains why the bats would come unlatched if they tried to roost head down.

The finding helps scientists understand how Myzopoda lives in the wild. The bat, a small creature about two inches long and weighing one-third of an ounce, roosts on the slick surface of broad, fan-like leaves located high off the ground in an indigenous tree called Travelers' Palm (Ravenala madagascariensis).

Daniel Riskin The researchers' finding also settles speculation that Myzopoda differs from its head-up roosting alter ego, Thyroptera, which is a suction-footed species that lives in tropical climes in Central and South America. The question is, with two species living in similar tropical environments under similar competitive pressures, which adhesive technique came first?

Riskin believes that Thyroptera is a later stage of evolution of the two bats. Why? While Myzopoda, through wet adhesion, can only roost head-up, Thyroptera, using suction, can roost either head-up or head-down. In terms of evolution, Riskin noted, "It doesn't make sense to go through suction to get to wet adhesion, but it does make sense to go through wet adhesion to get to suction."

Female fruit flies can be 'too attractive' to males

2009-12-07T23:27:00.000+05:30

Females can be too attractive to the opposite sex – too attractive for their own good – say biologists at UC Santa Barbara. They found that, among fruit flies, too much male attention directed toward attractive females leads to smaller families and, ultimately, to a reduced rate of population-wide adaptive evolution.

In an article published in the December 8 issue of Public Library of Science Biology, the authors described their experiments on the sex lives of fruit flies.

"Can females be too good looking?" asks William Rice, biology professor at UCSB. "Can there be disadvantages to being attractive? The answer is yes: If you are too attractive, you get too much male attention, and that interferes with your ability to function biologically."

The authors explain that the term "good looking," among fruit flies, refers to something, like a large body. From the perspective of a male fly, a desirable mate is a female that is larger and can therefore produce more offspring.

"These larger females are disproportionately courted and harassed by males attempting to obtain matings," said Tristan A. F. Long, the study's first author. "When these males are 'choosy' with their courtship, there may be negative consequences to the species' ability to adaptively evolve."

According to the scientists, too much mating is harmful to the females because seminal fluid from the male has toxic side effects. Too much courtship can also hinder the female's ability to forage effectively.

"When they court the females, the males sing to them; they do this by vibrating their wings," said Rice. "They dance and sing at the same time. This might sound romantic, and it would be if it only happened once. But males are doing it all the time. This courtship is unrelenting – like mosquitoes on a warm summer night – as the male fruit flies try to persuade females to mate. The males are so persistent that they get them to mate almost every day."

In many species, females are frequently subject to intense courtship "harassment" from males attempting to obtain additional mating, according to the researchers. These coercive activities can result in attractive females becoming less fit to reproduce – a factor that has a major effect on the entire population.

"We found that when harmful courtship behaviours were directed predominantly toward larger females of greater fecundity potential – and away from smaller females, of lesser fecundity potential – this resulted in an overall reduction in the variation of lifetime reproductive success of females in the population," said Long.

The male-mediated, persistent courtship bias can have important consequences for the ability of a population to adaptively change over time. If, for example, a female acquires a mutation that increases metabolic efficiency, allowing her to grow larger, and produce more offspring over her lifetime, this mutation should rapidly spread through the population. However, if the males get in the way of the biological success of these more attractive females, the mutation won't spread through the population as well as it might if males courted females indiscriminately.

The experiments clearly showed that the evolutionary adaptation of fruit flies is hindered by this mating situation. "This change in the distribution of fitness represents a previously unappreciated aspect of sexual selection – one with important implications for the ability of beneficial genetic variation to spread through the gene pool, and ultimately for a species' capacity to adaptively evolve," Long explained.

List of 'unsung' wildlife affected by climate change released

2009-12-07T00:02:00.001+05:30

The Wildlife Conservation Society has released a list of animals facing new impacts by climate change, some in strange and unexpected ways.

In a new report titled "Species Feeling the Heat: Connecting Deforestation and Climate Change," the Wildlife Conservation Society profiles more than a dozen animal species and groups that are facing threats due to climate change impacts including: changing land and sea temperatures; shifting rain patterns; exposure to new pathogens and disease; and increased threats of predation.

The Wildlife Conservation Society is issuing this report as the world gathers in Copenhagen to address climate change issues and as the United Nations launches in 2010 the International Year of Biodiversity, a UN-led effort to raise awareness to reduce the constant loss of biological diversity worldwide. The Convention on Biodiversity, which emerged from the 1992 Rio Earth Summit, recently admitted that none of its 2010 biodiversity targets have been met, underscoring the dire situation wildlife around the world face from burgeoning threats such as climate change.

The report also highlights the huge role of deforestation in climate change. Nearly 20 per cent of greenhouse gas emissions are the result of deforestation, more than the output of all the world's trucks, trains, cars, planes, and ships combined, so protecting the remaining swaths of the world's forests can help put the breaks on climate change.

"The image of a forlorn looking polar bear on a tiny ice floe has become the public's image of climate change in nature, but the impact reaches species in nearly every habitat in the world's wild places," said Dr. Steven E. Sanderson, President and CEO of the Wildlife Conservation Society. "In fact, our own researchers are observing direct impacts on a wide range of species across the world."

The report contains a cross-section of animal species around the globe, including:

Bicknell's thrush, a bird species that breeds and nests in the higher elevations on mountains in northeastern North America. Slight increases in temperature threaten this bird's breeding habitat.

Flamingos, a group including several species that are threatened by climate change impacts that affect the availability and quality of wetland habitat in the Caribbean, South America, Asia, and Africa.

Irrawaddy dolphin, a coastal species that relies on the flow of fresh water from estuaries in Bangladesh and elsewhere in Southeast Asia. Changes in freshwater flow and salinity may have an impact on the species long-term survival.

Musk ox, a species that exists in the harsh environment of the Arctic Tundra. This Pleistocene faces a higher predation risk by grizzly bears, as more bears may move northward into the musk oxen's tundra home.

Hawksbill turtle, an ocean-going reptile with temperature dependent biology. Specifically, higher temperatures result in more female hatchlings, a factor that could impact the species' long-term survival by skewing sex ratios.

"Aside from all of the current political disagreements on meteorological data, we can say with certainty that climate change is threatening our planet with significant losses to wildlife and wild places," added Sanderson.

Aggression-promoting pheromone in flies

2009-12-06T22:10:00.000+05:30

One way a male Drosophila shows aggression is by "lunging," in which it rears up on its hind legs and snaps down with its forelegs on its opponent. Photo: Caltech/Liming Wang and Michael MaireStudy, published in Nature, also identifies pheromone-detecting neurons in the fly's antenna.

Have you ever found yourself struggling to get your order taken at a crowded bar or lunch counter, only to walk away in disgust as more aggressive customers elbow their way to the front? It turns out that flies do much the same thing, according to biologists from the California Institute of Technology (Caltech).

Reporting in the advance online edition of the journal Nature, the scientists say they have identified an aggression-promoting pheromone that controls such behaviours, and have pinpointed the neurons in the fly's antenna that detect this pheromone and relay the information to the brain to elicit aggression. Their results provide an important first step toward unravelling the mystery of how aggression – an innate (unlearned) behaviour – is hardwired into the brain by an animal's genes.

Pheromones – specific chemicals used by a particular species to communicate and to control their behaviour – have been identified in the scent glands of other insect species, such as ants and beetles, and have been shown to elicit aggressive behaviour when presented in synthetic form to the insects. It has been difficult, however, to prove that the insects normally use these pheromones to control their aggressive behaviour; notes study co-author David Anderson, Caltech's Seymour Benzer Professor of Biology and a Howard Hughes Medical Institute investigator.

"Obtaining such proof required the ability to experimentally interfere with the insects' capacity to sense the pheromone," he explains. "And that, in turn, necessitated identification of the receptor molecules that detect aggression pheromones, and of the olfactory sensory neurons that express these receptors."

As it turns out, the only insect in which these conditions could be met was the vinegar fly, Drosophila melanogaster, explains Liming Wang, a graduate student in Anderson's lab and the Nature paper's first author. "The genetic/molecular architecture of the olfactory system in Drosophila is well understood," Wang explains. "Thus, one can easily test whether a specific olfactory receptor, and the sensory neurons expressing it, are involved in a given behaviour."

Wang discovered that 11-cis-vaccenylacetate (cVA) – a pheromone present in the male fly's cuticle – "robustly promotes aggression in pairs of male flies," Anderson says.
Aggressive behaviour in Drosophila consists of brief "lunges" in which one fly rears up on its hind legs and snaps down with its forelegs on its opponent. When Wang and Anderson added synthetic cVA to an "arena" in which combatant flies were tested, the frequency of lunges was dramatically increased.

Building upon earlier work from other laboratories that had identified the receptors for this pheromone, Wang next showed that silencing the neurons in the fly's antenna that contain these specific receptors could block the ability of synthetic cVA to promote aggression.

These findings allowed Wang and Anderson to test whether flies can actually detect the release of this pheromone from other flies – and whether such detection promotes aggression.

To do this test, they trapped between 20 and 100 "donor" male flies – so called because they "donate" the volatile pheromones into the surrounding environment – in a tiny cage surrounded by a fine mesh screen. The screen allowed pheromones to escape, but kept the donor flies inside.

The researchers then measured the effect these donor flies had on the aggressiveness of a pair of "tester" male flies placed on top of the cage. The tester flies were close enough to sense the pheromone, but were prevented from coming into contact with the donor males by the mesh screen. "Remarkably," says Anderson, "the presence of the caged donor flies strongly increased aggression between the tester flies, and this aggression-promoting effect increased with a higher number of donor male flies."

Most importantly, the effect of the donor flies on the aggressiveness of the tester flies could be blocked by inactivating, in the tester flies' antennae, the neurons that sense the aggression pheromone.

"These experiments suggested that the presence of high densities of male flies in a local environment can indeed promote aggression through their release of cVA and its detection by other flies," Wang explains.

Based on these findings, Wang and Anderson began to speculate whether this pheromone might play a role in limiting the population density of male flies in a given environment. Normally, male flies are attracted to food in order to feed and because it gives them the opportunity to mate with feeding female flies. If the density of male flies on a food resource is too high, however, the competition between the flies might prevent feeding and mating. Since aggressive flies tend to chase away their competitors, an aggression-promoting pheromone should tend to keep the density of flies from becoming too high.

Wang tested this hypothesis by allowing a small number of flies to compete for a limited supply of food, while genetically manipulating their cVA-receptor neurons to make those neurons hyperactive.

Surprisingly, says Anderson, the flies with the hyperactive neurons quickly dispersed, leaving the food resource behind. "They fought one another until a dominant fly became 'king of the hill' and drove the other flies away," he explains.

"In contrast," Anderson adds, "flies whose genes weren't manipulated in this way ate happily together, like cows grazing placidly on an alpine meadow."

According to Wang and Anderson, these results suggest that when the population of male flies reaches a high-enough density, the concentration of cVA rises to a level that promotes aggression, forcing some of the flies off the food. The departure of those flies causes the ambient concentration of the pheromone to decrease, thereby decreasing aggression. "Once this occurs," says Wang, "the population becomes stabilised at an optimal density until more flies become attracted to the food, and the cycle repeats itself."

Although their observations of this behavior were made under artificial laboratory conditions, the researchers believe that it should be possible to test their hypothesis in the wild.

The discovery of the fly's response to an aggression pheromone raises a number of intriguing questions, such as whether this fly pheromone might be sensed by humans. This is very unlikely, says Anderson, as pheromones have evolved as a "private" chemical communication channel within a given species.

But that does not mean humans lack aggression pheromones altogether, he notes. After all, aggression-promoting pheromones have been discovered in mice, which are evolutionarily closer to humans than flies. It is possible, therefore, that humans have their own aggression-promoting pheromones.

"Do these pheromones keep the lines from getting too long at a crowded lunch counter, as irate patrons jockey for position in the queue and some walk away in frustration?" Anderson asks. "Only time will tell."

Birds and climate change: indicators of a changing world

2009-12-04T22:36:00.001+05:30

Next week, the world's governments are meeting at the United Nation's Climate Change Conference in Copenhagen, Denmark to attempt to agree action to tackle climate change. The outcomes of this will have resounding consequences for biodiversity.

Climate change is already having multiple impacts on birds and their habitats, and is exacerbating many of the factors which have put one in eight of the world's birds at risk of extinction. Many species may have to shift their ranges to survive, and considerably more losers than winners are expected.

One global study estimates that 15–37 per cent of species could be committed to extinction by 2050 as a consequence of climate change; another that each degree of warming could drive another 100-500 bird species extinct. Temperature rises beyond 2^°C are predicted to lead to catastrophic effects on birds, nature, people and the global economy.

Climate change is impacting birds in several ways:

range shifts and contractions (poleward in latitude and upward in altitude)

population declines

changes in behaviour and phenology such as the timing of egg-laying, breeding, and emergence of insects as food source

disruption of species interactions (predators and prey) and communities

exacerbation of other threats and stresses, such as disease, invasive species, and habitat fragmentation, destruction and degradation

increased extreme weather events

loss of coastal habitats including feeding areas for shorebirds and nesting sites for seabirds, or entire island ecosystems, due to sea-level rise

ocean warming effecting ocean productivity, bringing knock-on effects further up the food change

"The BirdLife Partnership is involved in several ground-breaking studies monitoring the impacts of climate change on birds", said Melanie Heath, BirdLife's Senior Advisor on Climate Change.

"For example, analyses of citizen-gathered data from the past 40 years by Audubon (BirdLife in the USA) revealed that 58 per cent of the 305 widespread species that winter on the continent have shifted significantly north since 1968, some by hundreds of kilometres."

In this study, movement was detected among species of every type, including more than 70 per cent of highly adaptable forest birds. Only 38 per cent of grassland species exhibited movement however, reflecting the constraints of their severely-depleted habitat and suggesting that they now face a combined threat of the loss of habitat and climate space. Audubon scientists say the ongoing trend of movement by some 177 species - closely correlated to long-term winter temperature increases - reveals an undeniable link to the changing climate.

Another important project that BirdLife has been involved in is A Climatic Atlas of European Breeding Birds. Described as a 'landmark' in our understanding of how climate change will affect wildlife, the atlas uses 'climate envelope modelling', and predicts that without vigorous and immediate action against climate change, the potential future distribution of the average European bird species will shift by nearly 550 km north-east by the end of this century, reduce in size by a fifth, and overlap the current range by only 40 per cent.

Three quarters of all Europe's nesting bird species are likely to suffer declines in range. Arctic and sub-Arctic birds, and some Iberian species, are projected to suffer the greatest potential range loss. Projected changes for some species found only in Europe or with only small populations elsewhere, suggest that climate change could set some on a path to extinction.

By 2100, sea-level rise could be between 0.5 and 1.4m, irreversibly altering small islands, reefs, atolls and, in turn, the low-lying coastal and intertidal habitats of many shore-nesting birds such as terns. A disproportionately high number of threatened birds occur on islands. Research in the North-western Hawaiian Islands suggests that sea-level rise could cause the loss of a significant proportion of the nesting sites for the Vulnerable Laysan Phoebastria immutabilis and Endangered Black-footed Albatross P. nigripes, and of the most populous remaining breeding sites for the Near Threatened Tristram’s Storm-petrel Oceanodroma tristrami. Similar sea-level rise scenarios applied throughout the Pacific would virtually eliminate the Endangered Phoenix Petrel Pterodroma alba and Vulnerable White-throated Storm-petrel Nesofregetta fuliginosa.

BirdLife’s data shows that over 400 bird species have already had documented climate-driven impacts to date. Given that the actual rise in global average temperature to date has been relatively modest, this is sobering. It suggests that the impact of future climate change on biological communities, and consequently ecosystem integrity, will be severe unless global emissions are cut by the amount needed to limit global average temperature rises to well below 2°C above pre-industrial levels. The world’s leaders need to act now and reach agreement on a fair, ambitious and binding deal in Copenhagen.

Elevated CO2 levels may mitigate biodiversity losses from nitrogen pollution

2009-12-03T18:43:00.000+05:30

University of Minnesota study involved a 10-year outdoor experiment

Rising levels of carbon dioxide may overheat the planet and cause other environmental problems, but fears that rising CO₂ levels could directly reduce plant biodiversity can be allayed, according to a new study by a University of Minnesota scientist Peter Reich. In fact, rising CO₂ may actually help counteract losses of diversity from another environmental villain: the global rain of nitrogen from fertilisers and exhaust fumes.

The study, published in this week's edition of Science magazine, involved a 10-year open-air outdoor experiment in which 48 plots planted with 16 different species of grassland plants were tested using ambient and elevated levels of nitrogen and carbon dioxide. Researchers measured the number of species observed in each plot, the plant biomass both above and below ground, as well as factors related to soil, water and light that might affect plant growth.

Over time, the diversity of plants growing in the research plots changed significantly, depending on the combinations of plants and the way added CO₂ and nitrogen affected the health of different species. One of the study's key findings is that while the combination of ambient carbon dioxide and nitrogen pollution reduces species richness by 16 per cent, adding more CO₂ to the mix reduces that change by half.

"From a biodiversity perspective, there was no evidence to support the worst-case scenario, in which impacts of rising CO₂ and nitrogen deposition combine to suppress diversity by 30 per cent, 40 per cent or even 50 per cent or more," Reich said. "Instead, their interaction ameliorated the diversity loss due to nitrogen enrichment that occurs under ambient CO₂. Given the importance of biodiversity to the effective health and function of our ecosystems this is good news, or perhaps better labelled as "not quite as bad" news".

Reich, a Regents professor in the department of forest resources, notes that "while it is a relief to find out that rising CO₂ and nitrogen together may not directly cause enormous losses of diversity, any loss of diversity is troubling, and in any case, this finding does not detract from the urgent need for us to curb CO₂ emissions given the other critical CO₂ effects, such as overheating the planet and threatening marine life through ocean acidification."

Species down, disease up

2009-12-03T16:05:00.000+05:30

The extinction of plant and animal species can be likened to emptying a museum of its collection, or dumping a cabinet full of potential medicines into the trash, or replacing every local cuisine with McDonald's burgers.

But the decline of species and their habitats may not just make the world boring. New research now suggests it may also put you at greater risk for catching some nasty disease.

"Habitat destruction and biodiversity loss," – driven by the replacement of local species by exotic ones, deforestation, global transportation, encroaching cities, and other environmental changes – "can increase the incidence and distribution of infectious diseases in humans," write University of Vermont biologist Joe Roman, EPA scientist Montira Pongsiri, and seven co-authors in BioScience.

Their study, "Biodiversity Loss Affects Global Disease Ecology," will appear in the December issue of the journal, available online on Dec. 7.

Diseases go global

"Lots of new diseases are emerging and diseases were once local are now global," says Roman, a wildlife expert and fellow at UVM's Gund Institute for Ecological Economics. "Diseases like West Nile Virus have spread around the world very quickly."

This is not the first time humans have faced a raft of new diseases. About 10,000 years ago, humans invented farming. This move from hunting to agriculture brought permanent settlements, domestication of animals, and changes in diet. It also brought new infectious diseases, in what scientists call an "epidemiologic transition."

Another of these transitions came with the Industrial Revolution. Infectious diseases decreased in many places while cancer, allergies and birth defects shot up.

Now, it seems, another epidemiologic transition is upon us. A host of new infectious diseases – like West Nile Virus – have appeared. And infectious diseases thought to be in decline – like malaria – have reasserted themselves and spread.

"Ours is the first article to link the current epidemiological transition," says Pongsiri, an environmental health expert in EPA's Office of the Science Advisor, "with biodiversity change, decline and extinction."

"People have been working on this in individual diseases but no one has put all the studies together to compare them," says Roman. In 2006, he and Pongsiri gathered a group of scientists and policy analysts with expertise in a range of the new diseases being observed – including West Nile virus as well as malaria, the African parasitic disease schistosomiasis, hantavirus pulmonary syndrome, and several others. From that meeting, the forthcoming BioScience study developed.

"We've reviewed all those studies and show that emergence or re-emergence of many diseases is related to loss of biodiversity," says Pongsiri.

"We've taken a broad look at this problem to say that it's not just case-study specific," she says. "Something is happening at a global scale."

Of mosquitoes and mice

One of the studies that Pongsiri and Roman's team examined was a 2006 investigation in Amazonian Peru. It was the first to demonstrate that malaria transmission can rise in response to deforestation. Though the mechanisms are complex and not fully worked out, it appears that loss of the structural diversity provided by trees led to higher density of Anopheles darlingi mosquitoes, a potent transmitter of malaria, as well as to higher biting rates.

"Or think about Lyme disease," says Roman, calling from Connecticut.

People get this disease from ticks infected with a bacterium, Borrelia burgdorferi. The ticks, in turn, usually get the bacterium by feeding on small mammals – particularly white-footed mice.

"Historically, Lyme disease was probably rare, because you had a large range of mammals, everything from pumas all the way down to a widespread community of rodents," says Roman. Ticks feed on different species, and, since many are poor hosts for the bacterium, only a limited number of ticks would carry the disease to people. But fragmentation and reduction of forests has led to deep declines in the number of mammals – and white-footed mice tend to thrive in species-poor places, like small patches of forest on the edge of neighbourhoods.

"In fact, white-footed mice appear to be the most competent animal host reservoir of Lyme disease in the northeastern U.S.," Pongsiri notes on an EPA blog, "So, the more white-footed mice that are in the forest, the greater chance more ticks will be infected, and the greater chance you have of getting bitten by an infected tick."

In other words, if you're worried about catching Lyme disease, it's a good idea to wear long pants – but it might be a better idea to join your conservation commission or zoning board since "protecting large forested areas in the vicinity of residential areas may reduce the risk of Lyme disease," the BioScience paper notes.

Eco-epidemiology?

It is new to think about biodiversity – and therefore, species and land conservation – as integral to public health. Until recently, almost no epidemiologists, nor medical schools, were framing questions of human infectious disease prevention in terms of, say, habitat structure, promoting genetic diversity in non-human species, or protecting animal predators as ecosystem regulators. Human diseases, goes the conventional thinking, are best understood and treated by looking at humans.

"Now there is the beginning of a movement to bring epidemiology and ecology together," says Pongsiri.

"We're not saying that biodiversity loss is the primary driver for all of these emerging diseases," says Roman, "but it appears to be playing an important role."

"We're trying to make the case that all of these environmental changes we're making, because they are anthropogenic, can be managed, can be controlled," says Pongsiri. "We may be able to actually reduce or prevent these diseases by managing for biodiversity from the genetic level to the habitat level."

A third of the bird species on the planet are at risk of extinction and a quarter of the mammals, Roman says, "and we have an incredible amount of habitat being destroyed, along with climate change. We should expect to see the impacts of these changes occurring now, to people – and we do."

"The standard argument for protecting biodiversity is often that, well, there are medicines out there and you don't want to destroy a forest where you might have a cure for cancer," he says, "and that's true – but I don't think that's as compelling as the argument that if you cut down the forest you or your kids are more prone to infectious diseases."