Mercury Poisoning Makes Birds Act Homosexual

Metal may influence sexual development in white ibises, expert says.

White ibises perch in Galveston Bay near Smith Point, Texas (file photo).

Photograph by Joel Sartore, National Geographic

Christine Dell'Amore

Male birds that eat mercury-contaminated food show "surprising" homosexual behavior, scientists have found.
In a recent experiment in captive white ibises, many of the males exposed to the metal chose other males as mates.
These "male-male pairs did everything that a heterosexual pair would do," said study leader Peter Frederick, a wildlife ecologist at the University of Florida in Gainesville.
"They built their nest, copulated together, stayed together on a nest for a month, even though there were no eggs—they did the whole nine yards."
(Related: "Homosexual Activity Among Animals Stirs Debate.")
Wild white ibises—among the most common birds in Florida's Everglades—are exposed daily to mercury through their diets of crustaceans and other small invertebrates.
The prey animals take up mercury that's long seeped into the Everglades as a byproduct of industrial processes such as waste incineration.
Recent pollution-control measures have "grossly reduced" the contamination, Frederick said. Even so, the new study shows that ibises experience "fairly major reproductive problems at pretty low levels of [mercury]."


Contaminated Birds Produce Fewer Babies
During the five-year experiment, Frederick and colleague Nilmini Jayasena divided 160 young captive white ibises into four groups of equal numbers of males and females.
During the study period, male and female birds were allowed to choose their mates—an experimental first, according to the study authors.
"All other studies that involve reproduction in birds took a male and a female and put them in a cage," Frederick said. "Our finding, while novel, is the first time anybody's looked for it."
Starting at around 90 days of age, each of three groups was fed a diet containing either low, medium, or high amounts of mercury, based on a realistic range of exposures in the wild. A fourth control group ate mercury-free food.
Once the birds had reached sexual maturity at around a year old, homosexual bonding increased in all three groups exposed to mercury. This behavior led to a 13 to 15 percent decline in the number of young, compared to the mercury-free control group.
The metal also impacted heterosexual couples. Overall, female birds exposed to mercury yielded 35 percent fewer babies than the control group.
(Related: "Mercury Pollution's Oldest Traces Found in Peru.")
The biological mechanism for how the metal causes homosexual actions is not totally understood, Frederick added.
Mercury is a known endocrine disruptor—a substance that mimics or blocks the production of natural estrogen. In this case, exposed male birds' bodies produced more estrogen than testosterone as compared with control birds.
(See "Weed Killer Makes Male Frogs Lay Eggs.")
Though hormones can affect sexual behavior, estrogen or testosterone alone usually don't influence how a bird chooses a mate. This makes Frederick speculate that mercury exposure during the birds' sexual development may play a role.


Mercury Mysteries Remain
Many unknowns remain about the study and mercury's effects, Frederick warned.
The team did not have funding, for example, to examine whether taking mercury out of the birds' diets would stop the homosexual behavior.
But "my suspicion is none of the effects we saw are likely to be permanent," Frederick said. In general, mercury flushes from a bird's body within weeks if the animal isn't consistently exposed.
Frederick also emphasized that the study has no ramification for humans.
"There's a great tendency to extrapolate this study in an offhand fashion to mean, Oh if you eat mercury, you're going to be gay," he said.
In addition, the researchers can't say for sure whether homosexual behavior occurs in wild birds exposed to mercury. (See bird pictures.)
But at least one expert praised the white ibis study for showing a plausible effect of mercury poisoning in the wild.
One of the "great frustrations" for scientists is lab studies on environmental contamination that don't predict what happens in the wild, Lou Guillette, a zoologist at the Medical University of South Carolina, said in a statement.
"So a study like this that looks at environmentally appropriate levels of mercury is probably the most powerful kind of study to tell us what's going on in the real world," said Guillette, who was not part of the research.
Study author Frederick added that the research "gives us a very clear prediction to test—to get out and see whether there are males pairing with males in nature."
"This study badly needs to be replicated."

(From National Geographic Daily News)

'Left-handed' coiling snails survive more snake attacks

By Victoria Gill Science and nature reporter, BBC News

Snails with shells that coil anti-clockwise are less likely to fall prey to snakes than their clockwise-coiling cousins, scientists have discovered.

The arrangement of the snakes' teeth makes it difficult for the reptiles to grasp these "left-handed" snails.
The effect of this advantage on the survival of Satsuma snails is so great, say the researchers, that they could separate into a distinct species.
Biologists in Japan report the finding in the journal Nature Communications.

Angle of attack
Satsuma snails come in two forms: those which have shells that coil anti-clockwise, considered sinistral or "left-handed" and those that coil clockwise, considered "right-handed".
Land snails copulate face-to-face, and a snail with a reverse-coiled shell has its whole body reversed - including the position of its genitals.
This means that oppositely coiled individuals are anatomically incompatible when it comes to mating, so the scientists were puzzled as to why "reverse-coiled" snails continued to survive and evolve.

The arrangement of the snake's teeth makes it difficult to grasp the snails.

To investigate, the team, led by Masaki Hoso from Tohoku University in Sendai, set up "predation experiments".

They observed snail-eater snakes' (Pareas iwasaki) as they attempted to eat the snails.
To consume the soft-bodied molluscs, the predators had to extract them from their shells.
"When attacking, the snake always tilts the head leftward," Dr Hoso told BBC News.
The snake grasped the snail with its upper jaw and inserted its lower jaw into the shell to extract the soft body.

The "right-handedness" of this sequence of movements, Dr Hoso explained, means that the snake "cannot grasp [left-handed] or sinistral snails well".

The scientists wrote: "This study illustrates how a single gene for reproductive incompatibility could generate a new species by natural selection."

(From BBC News)

Giant fossil bird found on 'hobbit' island of Flores

By Emma Brennand Earth News reporter

Artist’s impression of the size of the giant stork next to a Homo floresiensis hobbit

A giant marabou stork has been discovered on an island once home to human-like 'hobbits'.

Fossils of the bird were discovered on the Indonesian island of Flores, a place previously famed for the discovery of Homo floresiensis, a small hominin species closely related to modern humans.
The stork may have been capable of hunting and eating juvenile members of this hominin species, say researchers who made the discovery, though there is no direct evidence the birds did so.
The finding, reported in the Zoological Journal of the Linnean Society, also helps explain how prehistoric wildlife adapted to living on islands.

Tall and heavy
The new species of giant stork, named Leptoptilos robustus, stood 1.8m tall and weighed up to 16kg researchers estimate, making it taller and much heavier than living stork species.

Palaeontologist Hanneke Meijer of the Smithsonian National Museum of Natural History in Washington DC, and affiliated to the National Museum of Natural History in Leiden, the Netherlands, made the
discovery with colleague Dr Rokus Due of the National Center for
Archaeology in Jakarta, Indonesia.

Finding large birds of prey is common on islands, but I wasn't expecting to find a giant marabou stork Palaeontologist Hanneke Meijer

They found fossilised fragments of four leg bones in the Liang Bua caves on the island of Flores.

The bones, thought to belong to a single stork, are between 20,000 to 50,000 years old, having been found in sediments dating to that age.
The giant bird is the latest extreme-sized species to be discovered once living on the island, which was home to dwarf elephants, giant rats and out-sized lizards, as well as humans of small stature.

"I noticed the giant stork bones for the first time in Jakarta, as they stood out from the rest of the smaller bird bones. Finding large birds of prey is common on islands, but I wasn't expecting to find a giant marabou stork," Dr Meijer told the BBC.
Only fragments of wing bones were found, but the researchers suspect the giant stork rarely, if at all, took flight.

Instead, the size and weight of its leg bones, and the thickness of the bone walls, suggest that the now extinct stork was so heavy that it lived most of its life on the ground.
It is thought to have evolved from flying storks that colonised the relatively isolated island.

Map showing the location of the Liang Bua caves on the island of Flores

"Flores has never been connected to mainland Asia and has always been isolated from surrounding islands. This isolation has played a key role in shaping the evolution of the Flores fauna," says Dr Meijer.
Many species on the islands evolved into either giants or dwarfs.
This phenomenon is known as the "island factor", and is thought to have been triggered by few mammalian predators being on the island. That led to abundant prey species becoming smaller, and other predators becoming larger.

"Larger mammals, such as elephants and primates, show a distinct decrease in size, whereas the smaller mammals such as rodents, and birds, have increased in size," explains Dr Meijer.
Among the giants evolved the giant stork, and the giant rat, Papagomys armandvillei, as well as Komodo dragons, the largest surviving species of lizard.
Dwarf species included the dwarfed elephant, Stedgodon florensis insularis, and the human species , popularly known as the 'hobbit' H. floresiensis.

BIG BIRDS More pictures of the bones of the now extinct giant stork (pictured above) can be viewed at the Zoological Journal of the Linnean Society (subscription required) Remains of the earliest known pelican, including a preserved beak, were discovered earlier this year in France Watch video of modern storks and other long-legged wading birds

Indeed, the remains of the giant stork were found in the same section of cave as the remains of H. floresiensis.
Discovered in 2004, H. floresiensis is thought to be a new human-like species standing just 1m tall, which survived until around 17,000 years ago.

It is thought to be descended from a prehistoric species of human - perhaps H. erectus - which reached island South-East Asia more than a million years ago.
"The status of this human contemporary has been subject of intense debate since its discovery," says Dr Meijer. "But in my opinion, the associated fauna is crucial in understanding the evolution of H. floresiensis."
The distinct difference in size between the 1.8 m-tall giant stork L. robustus and 1m-tall the tiny hominin H. floresiensis raises some interesting questions.

Would the hominin have eaten the giant stork?
Direct evidence of H. floresiensis 's diet is hard to come by, but it is suspected of hunting animals on the island for meat.
However, modern marabou storks mainly eat carrion, but they do take fish, frogs, and small mammals and birds.
So would the giant stork have eaten the hominin?

A modern, smaller marabou stork (Leptoptilos crumeniferus)

"Whether or not this animal may have eaten hobbits is speculative: there is no evidence for that," Dr Meijer told the BBC.
"But can not be excluded either."
The giant storks towered over the hobbits.
More importantly, juvenile hobbits were no bigger than giant rats that existed on the island, which themselves may have fallen prey to the giant stork, she adds.
As yet is it unclear why the giant stork, and the pygmy elephants and hobbit hominins, went extinct.
"But we have several clues," says Dr Meijer.
"All the bones of the giant marabou as well as those of the pygmy elephants and the hobbits are found below a thick layer of volcanic ash," suggesting a recent volcanic eruption.
"Second, the giant marabou and its contemporaries go extinct right before modern humans appear at the cave."
Around 15,000 years ago, the climate of Flores went from dry to being wetter, and a combination of any of these factors may have been enough to drive species on the islands to extinction.

(From BBC News)

Thousands of plant species 'undiscovered in cupboards'

By Neil Bowdler Science reporter, BBC News  

Species of Strobilanthes collected in "herbaria" 

and identified only decades later

More than 35,000 new species of flowering plants may be lying undiscovered in cupboards around the world, it is claimed.

Botanists looked at how long it takes for new species collected in the field to be identified, and found it often took decades.

They concluded that of the 70,000 flowering plants that experts believe are yet to be found, over half may already be in collections, awaiting identification.
The study is published in the Proceedings of the National Academy of Sciences.
Plants have been catalogued for hundreds of years. Traditionally, potential new species are dried and mounted on cardboard, labelled and placed in what is known as a herbarium for safekeeping.
There are around 3,000 herbaria worldwide, containing thousands and thousands of specimens.
Dr Robert Scotland of Oxford University spent some 15 years using these herbaria to research one particular genus of flowering plants called Strobilanthes. He found 60 new species lying undiscovered in such collections.

Together with colleagues, he decided to try and calculate how many undiscovered species of all flowering plants may be lying in such collections.
They assembled data for over 3,200 species identified since 1970 and looked at the lag between collection and identification.

They calculated that only 16% were described within five years of collection, while nearly one quarter were described over 50 years after they were first collected and placed in herbaria. One species took 210 years to be identified.

When the same pattern was projected into the future, the team concluded that over 35,000 species were likely to emerge from the herbaria collections over the next 35 years. That is half the estimated 70,000 new species of flowering plant that botanists still expect to find.

Number crunching "We'd been doing a particular study on a group of tropical plants called Strobilanthes. It's called a monographic study when botanists look at variation in different species across the whole of the globe," Dr Scotland told the BBC.

Click to play

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The BBC's Neil Bowdler found out more at the world's largest herbarium at the Royal Botanic Gardens, Kew

It is during these studies that botanists can eliminate duplications arising from different names being used for the same species in different countries, for example. But Dr Scotland's study delivered 60 new species from the depths of the herbaria collections.

"I was looking at those 60 species and what I noticed was that most of them were first collected by botanists over 60 years ago. I was quite surprised by that."

A new investigation and some number crunching led to perhaps more surprising results yet.
"What our study has shown is that only 16% of species were collected within five years of being described, whereas most get collected, they then make it into herbarium cabinets, then they sit there for up to 150 years until someone comes along and spots them."

So why are so many plants lying unidentified?
Dr Scotland puts it down to a lack of expertise and a lack of resources, but says examining these vaults may be every bit as important as future field studies.
"There are certainly places in the world which are under-collected where there's many things to be found. Botanists visit a particular rainforest, for example, and come back with a haul of species.
"[But] out of that 70,000 species still to be found, more than half of those have already been collected in the world herbaria and are waiting for someone with the relevant expertise and time to say 'that's a new one'."
Dr Mark Carine, of London's Natural History Museum and another member of the study team, said: "Lack of manpower and lack of expertise is obviously a major issue here. There's no doubt we just don't have enough people to complete the process as rapidly as we might like.

"I think what the study does is highlights the importance of collections such as the one at the Natural History Museum and elsewhere. We need to think about creative ways of unlocking information that we have in those herbaria as quickly as possible."

(From BBC News)

'Superscope' yields first glimpse of Double Quasar

 
The Double Quasar image bodes well for the UK's future in radio astronomy
 

The E-Merlin telescope has proven its capabilities with a striking image of a quasar nine billion light-years away.

E-Merlin is an array of seven linked UK radio telescopes, updated last year with fibre optic technology that has vastly increased its power.
Light from the Double Quasar has been bent by a massive object between it and the Earth, resulting in a double image.

This gravitational lensing is a powerful demonstration of one aspect of Einstein's theory of relativity.
The quasar - short for quasi-stellar radio source - sprays out tremendous amounts of energy and matter, powered by a super-massive black hole at its heart.
The E-Merlin image shows how gravitational lensing can produce multiple images of the quasar. Visible at the top is a rich picture of the quasar and the jet of radio waves coming out of it at near light-speeds.
Below that is a duplicate image of the quasar; just above it is the fainter image of the nearer galaxy that does the lensing.

The image demonstrates how the 2009 data-link upgrade for the array of telescopes, run from the Jodrell Bank observatory in Cheshire, has improved its vision.

Previously, the seven telescopes passed data to one another through antennas operating in the microwave region. It was a slow and lossy process that fibre-optic links have now replaced, with promising results.
"E-Merlin is going to be a transformational telescope," said Mike Garrett, director of the Netherlands Institute for Radio Astronomy. "Astronomers around the world can't wait to get their hands on it.
"As a pathfinder for the next-generation international radio telescope, the Square Kilometre Array, E-Merlin represents another giant leap forward for the global radio astronomy community."

(From BBC News)

Database shows how bees see world in UV

By Neil Bowdler Science reporter, BBC News

 
Creeping Zinnia as we see it (left) and with UV shades made 
visible (right). The petals appear two-toned to bees, the 
concentric colours drawing them towards the nectar

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."

 
    How a cactus appears in UV light
 

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 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."

( from BBC News)