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How bees see world in UV

By Neil Bowdler Science reporter, BBC News

Researchers are being offered a glimpse of how bees may see flowers in all their ultra-violet (UV) glory.

The Floral Reflectance Database (FReD) was created by researchers at Imperial College London and Queen Mary, University of London.

It enables researchers to "see" plant colours through the eyes of bees and other pollinating insects.

Bees have different colour detection systems from humans, and can see in the UV spectrum.

Details of the free database are published in the open-access journal PLoS ONE.

"This research highlights that the world we see is not the physical or the 'real' world - different animals have very different senses, depending on the environment the animals operate in," said Professor Lars Chittka from Queen Mary's School of Biological and Chemical Sciences.

"Much of the coloured world that's accessible to bees and other animals with UV receptors is entirely invisible for us. In order to see that invisible part of the world, we need this special machinery."

The researchers collected what's called "spectroreflective" measurements of the petals and leaves of a large number of different plants. These measurements show the colour of plants across both the visible and invisible spectrum.

Users of the database can then calculate how these plants appear to different pollinating insects, based on studies of what different parts of the spectrum different species see.

Scientists have inferred what colours insects see by inserting microelectrodes into their photoreceptors, and by using less invasive behavioural studies.

Seeing the world as insects may see it can reveal "landing strips" which are invisible to the human eye. These act to guide insects to the nectar they feed on.

These landing strips might take the form of concentric circles of colour or dots.

"Quite often, you will find in radial symmetrical patterns that there is a central area which is differently coloured. In other flowers there are also dots in the centre which indicate where there is basically an orifice for the bee to put in its tongue to extract the goods."

Greenhouse use

Creeping Zinnia as we see it (left) and with UV shades made visible (right)

But what is the point of such a tool beyond giving researchers an insect's view?

Professor Chittka says seeing these invisible colours may have commercial applications in the greenhouse and beyond.

"Every third bite that you consume at the dinner table is the result of insect pollinators' work. In order to utilise insects for commercial pollination purposes, we need to understand how insects see flowers.

"We need to understand what kind of a light climate we need to generate in commercial glass houses to facilitate detection of flowers by bees."

Co-author Professor Vincent Savolainen, from Imperial College London, says the database also offers us new perspectives on how plant colour evolved.

"We hope this work can help biologists understand how plants have evolved in different habitats, from biodiversity hotspots in South Africa to the cold habitats of northern Europe," he says.

"FReD's global records may show how flower colour could have changed over time, and how this relates to the different insects that pollinate them, and other factors in their local environment."

By:
Beliani Z.I

Beruang Kutub Terancam Punah? Wah Gawat !!!

Polar bear 'could still be saved'

By Neil Bowdler Science reporter, BBC News

The polar bear needs ice platforms to hunt for ringed and bearded seals

Cutting global greenhouse emissions might yet save the polar bear and its Arctic habitat, according to scientists in the US.

It has been suggested that emissions of greenhouse gases have already put the Arctic ice cap and the polar bear on an irreversible path towards extinction.

But a new study suggests rapid emission cuts could help preserve ice cover to save the iconic bear.

Details are published in the academic journal Nature.

A US Geological Survey team led by Dr Steven Amstrup predicted back in 2007 that two-thirds of the world's 22,000 polar bears would disappear by half way through the next century.

This was based on industrial emissions continuing on a "business as usual" basis.

Elsewhere, a study suggested industrial emissions of greenhouse gases might have already put the world on target for temperature rises which would result in rapid and perhaps irreversible ice loss in the Arctic.

Dr Amstrup and colleagues now say that such dire forecasts might be avoided if industrial societies act quickly to cut emissions.

Key to their argument is the conclusion that there is no "tipping point" in the Arctic beyond which the battle is lost.

"In this paper we looked at what would happen if we allowed greenhouse gas emission to rise up to the level where some of these rapid ice loss events started to occur but [we] then arrested the increase in emissions at that point," Dr Amstrup told the BBC.

"What we found is if we did that, then ice didn't just continue to decline after these rapid loss events, but there was some substantial recovery and then maintenance of sea ice throughout the century."

"The good news for polar bears is we haven't crossed a tipping point beyond which polar bears and their Arctic habitat can't recover."

Positive feedback

It is thought that a retreating Arctic ice cap will allow the sun to heat the open waters created by the ice's retreat, and this in turn will accelerate the melting of the remaining ice cap, perhaps irreversibly. This effect is an example of what is termed a "positive feedback".

Polar bears will feed on anything they can find if they cannot get access to the ice

But Dr Amstrup's team found in their models that there were effects which might counter this feedback mechanism.

"There are a number of other thermodynamic factors, such as the rapid freeze that results when you go from open water to cold conditions which reappear in the Fall," he says.

"The rapid freeze tends to compensate for the effects that are working to provide these potential tipping points."

Dr Ted Maksym, of the British Antarctic Survey (Bas), said he agreed there was little evidence of "tipping points" in the Arctic.

"All the literature that has looked for a tipping point for sea ice has essentially found none. This has been drowned out a bit by the noise surrounding the 2007 minimum [for summer ice loss] and a possible 'death spiral' for Arctic sea ice."

"The suggestion that if global temperature rise is kept below 1.25 degrees that polar bears will survive is encouraging; but given current trends this is not likely to be achieved. So we are by no means out of the woods."

Professor Julian Dowdeswell of the Scott Polar Research Institute at the University of Cambridge, said such research was important, but that reality could turn out to be different - something the authors of the paper have recognised.

"To have a good physical understanding of the natural world, it's important that we do run predictive models," he said.

"But it's equally important to remember that they are only models and not reality. Usually there is an envelope of possible futures, rather than one future."

'Pizzly bears'

Should the mathematical models prove wrong, or should industrial society mot move to curb emissions, then this week's Nature journal also looks at how it may end for the polar bear.

Dr Brendan Kelly of the US National Marine Mammal Laboratory, and colleagues, write in a separate comment piece about the possibility of increased cross-breeding between the polar and grizzly bears.

A polar bear with patches of brown fur was shot by hunters in 2006 and this year, a hunter killed a polar bear thought to be the offspring of a polar-grizzly hybrid.

Dr Kelly suggests that as the ice cap melts and polar bears go ashore, the natural barrier between the bear populations will fall, and such hybrids, dubbed "pizzly bears" by some, might become more commonplace.

He and his team have found 34 possible examples of such hybridisation among sea mammals in the region. Cross-breeding between the bowhead whale and the endangered North Pacific right whale could quickly push the latter towards extinction, he warns.

"Plans must be developed immediately to monitor the genetics of Arctic animals and to deal with hybrids before current discrete populations merge and at-risk species are bred out of existence," the team write in Nature.

Alhamdulillah... Ternyata beruang kutub yang sudah langka ini masih bisa terselamatkan..

By:
Beliani Z.I