An amphibious assault

LONDON

– The first images that come to mind may be unassuming brown newts or garden-variety green frogs, but amphibians cover a much grander spectrum.

Among about 6,000 species of frogs, salamanders and caecilians (legless animals, pronounced like “Sicilians”) are some of the world’s most bizarre animals: Giant Chinese salamanders, two metres in length; the “hairy frog” of Cameroon, which not only looks like it sports hair, but also can break its own bones to grow claws (an ability discovered just last month); the Surinam toad, which carries its eggs embedded in its back; and, even more macabre, the Sagalla caecilian, which feeds its own skin to its young.

Amphibians are also among the most colourful animals: The tiny, bright-yellow poison frog (with the spectacular scientific name Phyllobates terriblis) from Colombia, which is, gram for gram, the most poisonous vertebrate in the world; the black-dotted yellow frogs of Panama, which communicate with adorable hand waves; and the charismatic red-eyed tree frogs, aptly nicknamed “swimsuit calendar frogs.”

These make up just a small sample of the amazingly diverse amphibians, which have the longest history on earth. They predate all other terrestrial vertebrates.

But the first group of animals to colonize the land is also the first that humans are driving off it. Amphibians are disappearing faster than any other animals since the dinosaurs: 32 per cent of all species are threatened with extinction, compared with 23 per cent of mammals and 12 per cent of birds. Almost half are in decline.

The reasons are complex and vary among species. Some are hunted for the pet trade or, as with the Chinese salamander, for their meat. The destruction of habitat, as with all animals, is a major cause worldwide. Pollution also appears to be a big factor.

But one of the most worrisome and headline-grabbing causes is a strange fungus: Batrachochytrium dendrobatidis, a.k.a. chytrid. Nobody quite knows how it kills amphibians - it may smother them, covering the skin they use to absorb oxygen and water, or it might release toxins. But biologists are unanimous in their belief that it is wiping out amphibians across the tropics, in the warm and wet conditions in which they thrive, from Australia to South America. Scientists believe that it is behind the disappearance of 74 species (out of an original 110) of harlequin frog in Central America and at least 10 species of Australian frogs.

Bob Johnson, curator of reptiles and amphibians at the Toronto Zoo, saw one of the fungus’s first victims just before it vanished. The golden toad of Costa Rica was once so numerous that tourists would flock to witness their mating season. They were so dense on the forest floor, “we could barely walk, there were so many of them,” Mr. Johnson says of a trip he made in 1987. Just two years later, they had all disappeared, driven into extinction. “It was just astonishing.”

Now, Mr. Johnson is caring for one of the last populations of Panama golden frogs, the stars of the most recent David Attenborough BBC documentary, Life in Cold Blood. The frogs were all taken out of the wild before chytrid reached them too.

Humans may be responsible for the spread of the fungus: Scientists suspect that it came from its home in South Africa when clawed frogs were exported 50 years ago for use in pregnancy tests. (A dose of a pregnant woman’s urine causes a female clawed frog to lay eggs within eight to 12 hours. The test also works on male frogs, which produce sperm in response to the injection.)

African clawed frogs are mostly resilient to chytrid, and probably carried the fungus, but frogs elsewhere have little defence. It can wipe out a species in a matter of years.

Poster children

The reason for their vulnerability boils down to two things: They spend part of their lives in water and part on land, so they are exposed to factors in both environments; and their skin - not scaly like a reptile’s, but soft, thin and permeable - renders them more sensitive to things such as ultraviolet radiation, pesticides and disease.

As the most threatened group of animals on the planet, they are not just poster children for the biodiversity crisis, they are also harbingers of things to come. Because amphibians occupy a unique and crucial place in the food chain, their extinctions will ripple through the ecosystem and catalyze the rapid disappearance of other animals, large and small.

Their young - salamander larvae and frog tadpoles - are major bottom feeders. When they grow into adults and move onto land, they bring nutrients from the water with them.

“Usually water is a trap for biomass,” says McGill University zoologist David Green, one of Canada’s foremost authorities on amphibian declines. Things flow from land into water easily in rain, but amphibians, which move back onto land as adults, are one of the very few things in nature that move nutrients in the reverse direction, back onto land. “That’s a very important job,” Prof. Green says.

Moreover, as adults, they consume huge numbers of insects, then themselves are consumed in huge numbers by larger animals, such as birds and mammals. If we take these middlemen out of the food chain, the consequences could be disastrous. Insect populations could explode, while birds and mammals may disappear.

Yet, despite their importance, conservationists are struggling to raise the funds they need to save them.

“A charismatic bird or mammal will easily draw in money, but it is hard to get funding for amphibians,” says Helen Meredith, who is leading the Zoological Society of London’s EDGE amphibian-conservation program.

The London Zoo is caring for and breeding a number of spectacular amphibians, including the golden poison frog, and is sponsoring projects overseas for highly endangered amphibians such as the giant Chinese salamander (hunted for its meat in China, where it is considered a delicacy) and the spectacularly ugly purple frog of India, discovered just last year.

EDGE - meaning “evolutionarily distinct and globally endangered” - has found that 85 of the most distinctive and endangered 100 amphibian species are receiving little to no conservation attention. “Amphibians have been pushed into the shadows,” Ms. Meredith says.

“But in terms of conservation dollars, you can accomplish so much more than investing in any of the large ‘charismatic’ mammals,” says Kevin Zippel, director of Amphibian Ark, a branch of the World Conservation Union, which is supporting captive breeding programs.

Breeding amphibians is comparatively simple. They are small and fairly easy to take care of. “For just $50,000 to $100,000, you can save an entire amphibian species from extinction. Compare that to the amount it costs to rent one panda for a year from China: $1-million, and that doesn’t even include housing, food and staff.”

Amphibian Ark is trying to raise $50-million for the captive management of 500 species. “If each of the world’s largest zoos just took on one species each, we’d be done,” Mr. Zippel says.

“Though we aren’t saying that having these species in glass boxes is an acceptable form of conservation - it’s just an option for the future,” he adds.

Arks to tombs

But unless more effort is put into restoring their wild habitats, the “arks will only become tombs,” says ecologist Alan Pounds, who has been documenting the decline of golden toads and harlequin frogs in Central America since the 1980s. “We can’t save the world with captive breeding. We have always thought that if we have parks and reserves, then we can do what we want with the rest of the planet - and that is not true.”

He says the spread of chytrid in the mountains of Costa Rica is tied to global warming. His research, published in the journal Nature, indicates that the fungus causes more frog deaths in warmer years, when the hilltops - normally cool - become more hospitable to the fungus.

And it is happening not just in the mountains of Central America: Other researchers have tied the spread of the fungus in midwife toads in Spain to a warming climate.

But chytrid occurs in many places without being lethal. McGill’s Prof. Green has found it in about 13 per cent of amphibians from five Canadian provinces. “Canada would have to get warmer and wetter” for the fungus to become lethal, he says. “We may start to see that.”

Even if this doesn’t happen, frogs all over Canada are disappearing. Leopard frogs on the Prairies are vanishing, and nobody quite knows why. Fowler’s toads may be driven out of their only range, in Southern Ontario, where they are mowed over by beach grooming machines sent to remove cigarette butts. Chorus frogs in Quebec, along with their songs, are fading because of suburban development.

The precise causes can be hard to pin down, but many studies have implicated UV radiation, low doses of pesticides and agricultural pollution. Most ecologists believe that it is rarely one single factor that is responsible, but the combination of threats.

Ecologist Pieter Johnson at the University of Colorado published a landmark study in 2007 in the Proceedings of the National Academy of Sciences (PNAS) demonstrating that the combination of fertilizer runoff in ponds and the flatworm parasite Ribeiroia ondatrae may be responsible for the high prevalence of amphibian mutations that we see all over the United States and Canada (up to 70 per cent of frogs in some wetlands grow multiple arms and legs). High levels of fertilizers in ponds spawn blooms of algae, which in turn foster an explosion in snails which carry the parasites.

Many other studies have found such “synergistic effects.” Researchers from Oregon State University have shown that the combination of UV radiation and fertilizer pollution kills seven times more frogs than either alone.

Ecologist Rick Relyea at the University of Pittsburgh, who studies pesticides, reported in 2001 in the PNAS that subjecting tadpoles to the fear of a caged predator in their tank, combined with low levels of the pesticide carbaryl, caused grey tree frog tadpoles (found in Canada) to die when neither factor alone killed them. “Many people were shocked and amazed,” he says.

He has an upcoming paper in the journal Ecological Applications that will show that combinations of low doses of pesticides - non-lethal on their own - are “highly lethal.”

But Prof. Relyea cautions that we cannot be sure pesticides are causing frog declines in the wild - more research is needed. “The problem is that an awful lot of effort goes into assessing the benefits of these chemicals, but not the costs.” We just need to be smarter about how we use pesticides, he says, such as spraying them in minimal amounts and at times of year when amphibians are less vulnerable - for example, after the tadpoles have grown into frogs.

If pesticides are responsible for deaths in the wild, the impact could be more widespread than we realize. Ecologists from the University of Toronto reported last year that pesticides in the soils in Costa Rica were actually more concentrated higher up the mountains than lower down closer to plantations, carried aloft by breezes and deposited onto the mountaintops when mists form at high elevations.

Chemical cocktails

There is an important lesson to be learned here: Being so sensitive, amphibians are sending us a warning signal. For good reason, they are known as our canaries in the coal mine. “If we lose the amphibians, then we lose our best detection system to see what’s going on with the world,” EDGE’s Ms. Meredith says.

And not only that, we also lose “our tools for future drug production,” she says. Frogs harbour incredible cocktails of chemicals in their skin that are being investigated by medical researchers. The lethal poisons of arrow frogs may be harnessed for antibiotics, and seem to yield effective painkillers hundreds of times more powerful than morphine. The wood frog, widespread in Canada, can freeze solid and survive, and is being probed for clues to preserve frozen organs during transplant. Salamanders, which can regenerate their limbs, may some day help us to grow lost digits. And it was discovered just three years ago that certain red-eyed tree frogs produce a protein that can block HIV infection.

“On the back of some toad somewhere is the compound that will do wonders for you, but we don’t know which one it is yet,” Prof. Green says.

Already we have lost amphibian species to extinction that may have been able to help us. In the 1970s, scientists discovered a species of frog in Australia that gestated its eggs in its stomach, using special hormones to shut down its digestive system. It could have held the clues to treat ulcers, but it has not been seen in decades.

Before the 3,000 amphibians in decline suffer the same fate, is there anything we can do? When we are trying to fight the battle on so many fronts, is there any way to win the war?

We need to deal with every single issue at once: climate change, excessive use of agricultural fertilizers and pesticides, depletion of the ozone layer and, above all, habitat degradation.

But the case isn’t hopeless, Prof. Green says, as long as we take action now. “We have to give amphibians some credit,” he says. “They are not so vulnerable and fragile. It’s just the combination of factors that they cannot cope with. They are tough as boots if you give them a chance.”

Zoe Cormier is a science writer based in London.

HIGHLY ENDANGERED

Chinese giant salamander

The largest amphibian in the world. Has declined massively since the 1960s.

Primary threat is hunting. Considered a delicacy in China.

Chile’s Darwin frog

Carries young in mouth. May already be extinct.

Panama Golden Frog

No longer in the wild. Being bred at the Toronto and Vancouver zoos. Communicates with hand waves.

Olm

Blind. Lives in caves. May be able to live for more than 100 years and go without food for 10.

Purple frog

Just discovered in 2003. Critically endangered. Wonderfully ugly.

Golden poison frog

Most poisonous vertebrate on Earth.

***

WONDERFUL AND WEIRD

Hairy frog of Cameroon

Just spectacularly gross.

Pac man frog

Unlike any other amphibian, possesses teeth. Actually eats mice.

Australian red-eyed tree frog

One of many species of “red-eyed” tree frogs, or “swimsuit calendar frogs.” Produces protein in skin that can block HIV.

Surinam toad

Breeds young embedded in its back.

Betic midwife toad

Carries eggs around in a ball around its legs.

Zoe Cormier

From globeandmail.com

Unique Adaptive Evolution Found In Snake Proteins Provide New Insight Into Vertebrate Physiology

Prior to the advent of large sequence datasets, it was assumed that innovation and divergence at the morphological and physiological level would be easily explained at the molecular level. Molecular explanations for physiological adaptations have, however, been rare. Pollock and colleagues now provide evidence that major macroevolutionary changes in snakes (e.g., physiological and metabolic adaptations and venom evolution) have been accompanied by massive functional redesign of core metabolic proteins.

“The molecular evolutionary results are remarkable, and set a new precedence for extreme protein evolutionary adaptive redesign. This represents the most dramatic burst of protein evolution in an otherwise highly conserved protein that I know of,” said Dr. David Pollock, a professor of Biochemistry & Molecular Genetics at the University of Colorado Denver School of Medicine.

Over the last ten years, scientists have shown that snakes have remarkable abilities to regulate heart and digestive system development. They endure among the most extreme shifts in aerobic metabolism known in vertebrates. This has made snakes an excellent model for studying organ development, as well as physiological and metabolic regulation. The reasons that snakes are so unique had not previously been identified at the molecular level. In this recent study by Pollock and colleagues, the researchers show that mitochondrially-encoded oxidative phosphorylation proteins in snakes have endured a remarkable process of evolutionary redesign that may explain why snakes have such unique metabolism and physiology.

Amino acids that are normally highly conserved in these proteins have been altered, affecting key molecular functions such as proton transfer (which establishes a proton concentration gradient that drives energy production in the cell). In addition to the accelerated burst of amino acid replacements, evidence for adaptation comes from the remarkable levels of molecular coevolution and convergence that were observed.

The function of core oxidative metabolic proteins in vertebrates remains extremely controversial, mostly because of the difficulty of experimentally manipulating these membrane-embedded proteins. By integrating analyses of molecular evolution with protein structural data, the authors show that critical functions of mitochondrial proteins, such as the channeling of oxygen, electrons, and protons through cytochrome C oxidase, have been fundamentally altered during the evolution of snakes. Snakes have been previously proposed as an ideal metabolic, physiological, and ecological model system to study evolution, and the current results support that idea, showing that their utility as a model system can extend to the molecular level.

“Snakes are an invaluable resource for structural biologists and biochemists, who can use comparative genomics to generate hypotheses on how COI and oxidative phosphorylation function, and how these functions may be altered and redesigned,” said Dr. Todd Castoe, a lead author on the paper.

“We believe that our results will provide a textbook case as the most clear and dramatic example of adaptive evolution in a core metabolic protein to date, as well as providing the implication that strong molecular and physiological adaptation can be linked,” said Pollock.

“The manuscript represents an important milestone in molecular evolution and vertebrate adaptation, and opens up clear and well-justified directions for further research. Snake metabolic proteins may significantly clarify understanding about the operation of these critical yet functionally elusive metabolic proteins.”

Funding was provided through an NIH training grant and other NIH grants. These funding sources had no role whatsoever in preparation of the manuscript.

From ScienceDaily

Still just a lizard

I found a blogpost that I can´t help myself from sharing with you..

“The title gets the principal objection of any creationist out of the way: yes, this population of Podarcis sicula is still made up of lizards, but they’re a different kind of lizard now. Evolution works.

Here’s the story: in 1971, scientists started an experiment. They took 5 male lizards and 5 female lizards of the species Podarcis sicula from a tiny Adriatic island called Pod Kopiste, 0.09km², and they placed them on an even tinier island, Pod Mrcaru, 0.03km², which was also inhabited by another lizard species, Podarcis melisellensis. Then a war broke out, the Croatian War of Independence, which went on and on and meant the little islands were completely neglected for 36 years, and nature took its course. When scientists finally returned to the island and looked around, they discovered that something very interesting had happened.

The original population of P. sicula was still present on Pod Kopiste, so we have a nice control population. These lizards are small, fast, insect-eaters in which the males defend territories.

Sadly, P. melisellensis on Pod Mrcaru had been extirpated. So we had a few innocent casualties of the experiment.

The transplanted P. sicula thrived and swarmed over the island of Pod Mrcaru, but they were different, and they had evolved in multiple ways.

The original P. sicula were insectivores who occasionally munched on a leaf; approximately 4-7% of their diet was vegetation. The P. sicula of Pod Mrcaru, though, had adopted a more vegetarian diet: examining their gut contents revealed that 34% of their diet was plants in the spring, climbing to 61% in the summer…and much of this diet was hard-to-digest stuff, high in cellulose. This is a fairly radical shift.

There were concomitant changes. The lizards’ skulls were wider, deeper, and longer, and they had stronger bites — a necessity for chomping off bits of tough plants, instead of soft mosquitos. Instead of chasing bugs, they’re browsing stationary plants, and their legs are shorter and they are slower. Population densities are higher. The Pod Mrcaru lizards no longer seem to defend territories, so there have been behavioral changes.

Still just a lizard, I know.

Now here’s something really cool, though: these lizards have evolved cecal valves. What those are are muscular ridges in the gut that allow the animal to close off sections of the tube to slow the progress of food through them, and to act as fermentation chambers where plant material can be broken down by commensal organisms like bacteria and nematodes — and the guts of Pod Mrcaru P. sicula are swarming with nematodes not found in the guts of their Pod Kopiste cousins.

Here’s a photo (how could I resist an opportunity to show some lizard guts?). The top ones may be a little difficult to interpret; what they’ve done is slit open the tube of the gut, and then use some pins to hold the tube open so you can see the little ridge or flap that rings the interior.

The cecal valves are an evolutionary novelty, a brand new feature not present in the ancestral population and newly evolved in these lizards. That’s important. This is more than a simple quantitative change, but is actually an observed qualitative change in a population, the appearance of a new morphological structure.

Evolution created something new, and it did it quickly (about 30 generations), and the appearance was documented. It’s still just a lizard, but we expected nothing else — and it’s now a lizard with novel adaptations for herbivory.”

From Pharyngula`s blog.

“Living Dinosaur” Is Fastest-Evolving Animal

New Zealand’s “living dinosaur,” the tuatara, hasn’t changed its look in millions of years. But the reptile is actually evolving faster than any other animal studied so far, new DNA analysis reveals.Scientists recovered DNA from 8,000-year-old tuatara bones and compared it with DNA in blood samples from living tuatara. The modern species is the only surviving member of the order Sphenodontia, which flourished around 200 million years ago.

The results showed that tuatara evolve faster than bears, horses, and many other warm-blooded vertebrates.

(Related: “‘Instant’ Evolution Seen in Darwin’s Finches, Study Says” [July 14, 2006].)

Slowpokes

“Tuatara do most things slowly,” said study lead author David Lambert of New Zealand’s Massey University. He and colleagues published the findings in the March issue of the journal Trends in Genetics.

Tuatara “have a very low metabolic rate. So you would be forgiven for thinking that they haven’t been doing very much over 200 million years of evolution.”

But Lambert said the reptile’s ancient anatomy hides the rapid evolution of DNA within the animals’ cells.

“What [the research] is telling us is that the processes that govern anatomical evolution are quite different from those governing molecular evolution.”

Axel Meyer, of the University of Konstanz in Germany, agreed.

“There can be a real disconnect” between an animal’s physical and genetic evolution rates, said Meyer, who was not involved in the research.

“Fast [evolution] does not necessarily imply ‘good’ or ‘adaptive,’” he added.

He also cautioned against an assumption that so-called living fossils are somehow backward.

For example Meyer’s work on the coelacanth—a 300-million-year-old fish species thought to be extinct until 1938—showed that the fish do not evolve more slowly than “normal” species.

(See a picture of a coelacanth captured in 2007.)

Genetic Vigor

Lead author Lambert said the tuatara’s genetic vigor came from the structure of its mitochondrial genome. Mitochondria are the powerhouses of the cell.

“When the molecule actually replicates itself, the two DNA strands separate from one another—this region on the genome is single-stranded for lot of the time,” Lambert said.

“And when you are single-stranded, you tend to accumulate more change.”

However, the tuatara’s dynamic DNA is not the secret of its extraordinary survival through millions of years, Lambert said.

“The tuatara of today is not some supercharged model of what was here 8,000 years ago. It’s the same tuatara—its survival is related more to where it lives.”

New Zealand split from the supercontinent of Gondwana 80 million years ago—before the advent of mammals. As a result, tuatara were not hunted by swift, smart predators until humans brought rats to the islands of New Zealand around a thousand years ago.

While the tuatara’s evolutionary rate beat out a field of living and extinct animals, Lambert said the differences were not that huge.

“This is because the mitochondrial genome—and the processes that govern it—is very similar in a lot of those animals.

“The big surprise in all of this is that tuatara are evolving as quickly as they are.”

New Survival Challenge?

The hardy reptile may face another survival test as human-induced climate change takes hold, experts say.

Conservationists are concerned that climate change may upset the sex ratios of hatchling tuatara, as warmer temperatures result in the birth of more males.

Lambert said the section of DNA his team studied would not help the lizard to adapt any better to global warming.

But he said tuatara populations had survived countless ice ages, possibly simply by shifting north or south as temperatures fluctuated.

“That’s important, because it illustrates how behavior can control evolution—not to cause animals to change, but to remain the same throughout climate change [events].”

From National Geographics

Harlequin Frog Rediscovered In Remote Region Of Colombia

After 14 years without having been seen, several young scientists supported by the Conservation Leadership Programme (CLP), have rediscovered the Carrikeri Harlequin Frog (Atelopus carrikeri) in a remote mountainous region in Colombia.

The critically endangered Carrikeri Harelquin frog was recently rediscovered by the Project Atelopus team in the Sierra Nevada de Santa Marta Mountains in Colombia’s Magdalena department. Colombia is one of the world’s richest countries in amphibian diversity with more than 583 species. Unfortunately, in the past several years, there has been a decline in amphibian populations especially in higher elevations in Colombia.

The Carrikeri Harelquin frog is native to the Sierra Nevada de Santa Marta Mountains in Colombia’s Magdalena province. The frog lives in the páramo habitat at an attitude of 4,000 meters and is approximately five centimeters in size.

This population is unique since it possesses orange markings, which are unusual for this species. Páramo is a neotropical grassland ecosystem located in high elevations between the upper forest line (about 3,100 meters in altitude) and the permanent snow line (about 5,000 meters). Nearly 57 percent of this ecosystem worldwide is found in Colombia.

“By discovering that the endangered frog still exists, we hope it will show how important conservation is,” said Luis Alberto Rueda, scientist for the Project Atelopus team who led the expedition. “And we plan to continue with our research so that we can better assist in helping to ensure that this frog will not become extinct.”

In addition to Rueda, who is part of the GECOH (Grupo de Ecofisiología, Comportamiento y Herpetologia) of the University of the Andes, the individuals who are part of the Atelopus team of scientist include: Oswaldo Cortes, Giovanni Chaves, Erika Salazar, Jose Gil, Sergio Pulido, Astrid Nossa, Fabian Tavera, Jenny Gallo, Ximena Villagrán and Nidia Rodriguez members of the Ecodiversidad Colombia Foundation.

The CLP, formerly known as the BP Conservation Programme, supports the vital work of a new rising generation of conservation professionals who are helping to drive practical projects addressing a wide range of global environmental issues from protecting sharks in Brazil to conservation of threatened amphibians in Colombia and endangered turtles in Cambodia to the assessment and conservation of threatened bird species in China.

Adapted from materials provided by The Conservation Leadership Programme.

From Science Daily

Lizard’s DNA evolves quickly

 New DNA research has questioned previous notions about the evolution of the tuatara.

In a study of New Zealand’s “living dinosaur” the tuatara, evolutionary biologist Professor David Lambert and a team from the Allan Wilson Centre for Molecular Ecology and Evolution recovered DNA sequences from the bones of ancient tuatara up to 8000 years old.  They found that although tuatara have remained largely physically unchanged over very long periods of evolution, at a DNA level they are evolving faster than any other animal yet examined. The research has been published in the prestigious international journal Trends in Genetics and features on the cover of the issue.

“What we found is that the tuatara has the highest molecular evolutionary rate that anyone has measured,” Professor Lambert says.

The rate of evolution for Adélie penguins, which Professor Lambert and his team have studied in the Antarctic for many years, is slightly slower than that of the tuatara. The tuatara rate is significantly faster than for animals including the cave bear, lion, ox and horse.

“Of course we would have expected that the tuatara, which does everything slowly – they grow slowly, reproduce slowly and have a very slow metabolism – would have evolved slowly. In fact, at the DNA level, they evolve extremely quickly, which supports a hypothesis proposed by the evolutionary biologist Allan Wilson, who suggested that the rate of molecular evolution was uncoupled from the rate of morphological evolution.”

Allan Wilson, who died of leukaemia in 1991, was a pioneer of molecular evolution. His ideas were controversial when introduced 40 years ago, but this new research supports them.

Professor Lambert says the finding will be helpful in terms of future study and conservation of the tuatara, and the team now hopes to extend the work to look at the evolution of other animal species.

“We want to go on and measure the rate of molecular evolution for humans, as well as doing more work with moa and Antarctic fish, to see if rates of DNA change are uncoupled in these species. There are human mummies in the Andes and some very good samples in Siberia where we have some collaborators, so we are hopeful we will be able to measure the rate of human evolution in these too.”

The tuatara, Sphendon punctatus, is found only in New Zealand and is the only surviving member of a distinct reptilian order, Sphehodontia, that lived alongside early dinosaurs and separated from other reptiles 200 million years ago in the Upper Triassic period.

From Science alert

Snakes use inner ear to locate prey: Study

Snakes can’t hear as they don’t have an ear, it is often believed. But, a new study has found that the reptiles do possess an “inner” ear with a functional cochlea which they use to detect vibrations caused by prey.A team of international researchers has carried out the study and found that the ears of the snakes are sensitive enough to not only hear the prey approaching, but also to allow the brain to localise the direction it is coming from.

According to the researchers, any disturbance at a sandy surface leads to vibration waves that radiate away from the source along the surface. These waves behave like ripples on the surface of a pond after a stone is dropped into water.

However, these sand waves propagate much quicker (the speed is about 50 metres per second) than at water surface. But, on the other hand much more slowly than for instance in stone and the amplitude of the waves may be as small as a couple of thousands of a millimetre.

“Yet, a snake can detect these small ripples. If it rests its head on the ground, the two sides of the lower jaw are brought into vibration by the incoming wave. These vibrations are then transmitted directly into the inner ear by means of a chain of bones attached to the lower jaw.

“This process is comparable to the transmission of auditory signals by the ossicles in the human middle ear. The snake thus literally hears surface vibrations,” the study’s lead author J. Leo Van Hemmen of the Technical University Munich was quoted by the ‘ScienceDaily’ as saying.

From Daily News and Analysis

New species of lizard found in Maharashtra

A new species of lizard was found in the Western Ghats of Maharashtra’s Satara district.

The distinctive new species of ground-dwelling lizard (gecko) of the genus Hemidactylus is described from the plateaus of the Satara district, the Bombay Natural History Society (BNHS) has said.

It is a member of a group of chiefly terrestrial Indian Hemidactylus species that have undivided, or only partly divided subdigital lamellae.

This new species has been discovered by Varad B Giri of the BNHS and Dr Aaron M Bauer of illanova University, USA. Their paper was published in the Journal Zootaxa in February 2008, the BNHS said.

At present this species is only known from the type locality, which lies in the south-central part of the Western Ghats of Maharashtra. This region is unique in the presence of large laterite or basaltic plateaus on the crests of mountains. Mostly semi-evergreen forest characterises the valley vegetation. Most of the plateaus support sparse vegetation, which is mostly evident in monsoon and in summer they look barren. Apart from their unique ecological features, these plateaus have a unique floral and faunal diversity.

The northern Western Ghats, especially the parts in Maharashtra, are relatively unexplored and there is little information regarding the amphibians and reptiles of this region. In the last four years three new species of amphibians have been discovered from Maharashtra.

All these new discoveries were the result of localised surveys with moderate search efforts. With intensive and systematic surveys it will be possible to further increase our knowledge of reptiles of the northern Western Ghats.

In Maharashtra, there are excellent examples of the highly diverse and intact Western Ghats forests, but in the Satara district the forest is more fragmented and is increasingly degraded by human exploitation. Though herpetologically unexplored, the occurrence of a new ground dwelling Hemidactylus highlights the uniqueness of this region. As this area has large expanses of plateaus, efforts are now being made to confirm the occurrence of this species from other likely areas.

From Sify.com

NJ doctors tap snake venom to treat stroke patients

New Jersey doctors are tapping an unlikely source to help stroke patients.

A snake being milked for venom to treat stroke patients.

The venom of the Malaysian pit viper is the potent ingredient found in an experimental drug called Viprinex now being tested at three New Jersey hospitals. When given intravenously, Viprinex has been shown to help dissolve clots that plug arteries and cut off oxygen and blood flow to the brain.

According to doctors, the major advantage of Viprinex, which also thins the blood, is that it may be effective as long as six hours after a stroke patient’s symptoms begin. That would double the window of the only government-approved clot-busting therapy, called tPA, which must be given within three hours.

The fact that less than five percent of stroke victims get to a hospital in time has greatly limited the use of tPa, or tissue plasminogen activator. In addition, some doctors are hesitant to use the drug, which has been available since 1996, because it causes bleeding in the brain in about six percent of patients.

“What many investigators have been looking for is something that can dissolve clots with less risk of bleeding,” said Martin Gizzi, the neurologist who heads the New Jersey Neuroscience Institute at JFK Medical Center in Edison, which is participating in a clinical trial of Viprinex.

Under the trial’s guidelines, some patients will receive Viprinex, while others get a placebo. Doctors won’t know who got the real thing until the research — which is being conducted at 200 sites worldwide — has been completed in 2009. Patients are followed for 90 days after receiving the drug so their level of recovery can be assessed.

The drug is derived from the venom of the Malaysian pit viper, an aggressive snake that inhabits forest edges across much of Southeast Asia and grows to about three feet in length. The venom is frozen before being purified and converted to a drug product, explained Warren Wasiewski, the scientist overseeing the trial for Neurobiological Technologies Inc., the Edgewater drug company that makes the drug.

From nj.com

Free Radicals Run In Lizard Families

In lizards, the level of free radicals - molecules that cause damage to cells, tissues and DNA - runs in families, says research published yesterday in the Royal Society journal, Biology Letters.

Researchers from the University of Wollongong found that the production of free radicals was higher in adults than children and varied between different families of lizard species. Currently, very little is known about the genetic properties of free radicals and this new research could help us understand the process of ageing.

Free radicals are released during chemical reactions and speed up the aging process. In humans, they are linked to diseases such as Alzheimer’s, cancer and diabetes. As we get older, so do the cells in our body which begin producing more free oxygen radicals.

From MedicalNewsToday