Saturday, July 25, 2009

New lizard species found in India

Cnemasspis Kolhapurensis
Cnemasspis Kolhapurensis is endemic to parts of India's Western Ghats

Scientists have discovered a new species of lizard in the lush Western Ghats mountain range in the Indian state of Maharashtra.

The small reptile is a form of gecko and was found by taxonomist Varad Giri in the Kolhapur district. It has been named Cnemasspis kolhapurensis.

Mr Giri and his co-workers published their findings in this month's edition of the Zootaxa journal.

It is the third new species of lizard recently discovered in the area.

Mr Giri, a curator at the Bombay Natural History Society, told the BBC that the Western Ghats has never been surveyed for amphibians and reptiles.

"A gecko of this particular character has not been recognised elsewhere in the world," he said.

Iridescent sheen

Mr Giri said he first noticed the lizard in 2005 during a survey of one of the forests in the area.

Varad Giri
Taxonomist Varad Giri first noticed the lizard in 2005

"When I first stumbled across it, the lizard looked like a normal specimen," he said.

"It was basically a form of gecko but then I saw that it was interesting because its scales were shiny."

He said that when the gecko was held up in a certain light, the tail dorsum exhibited an "iridescent sheen".

Iridescence is commonly reported in a variety of reptiles - but not geckos.

Once Mr Giri and his co-workers had analysed the specimen, they realised it was a previously unknown species.

They then enlisted the help of Dr Aaron M Bauer, an expert on lizards based at Villanova University in the US, to confirm the discovery.

Cnemasspis kolhapurensis are mostly small in size and have a circular, rather than elliptical, pupil. They are generally found in forests although some have also been found in areas inhabited by humans.

Mr Giri said it is a ground-dwelling specimen and can be seen in leaf litter or under rocks.

'Under threat'

"Presently this species is known only to this area. It is endemic to the northern parts of the Western Ghats," he added.

The Western Ghats mountain range is said to be one of the world's "biodiversity hotspots".

But analysts say that the area is at risk of a biodiversity crisis, because it has long been under threat from logging and human encroachment.

Mr Giri says the discovery may well help in arguments to preserve parts of the landscape.

"This is really important now because there is a lot of human interference and deforestation," he said.

Other new species of lizard previously discovered in the area were Hemidactlyus sataraensis and Hemidactylus aaronbaueri.


Wednesday, July 22, 2009

Dragonflies face uncertain future

Matt Walker
Editor, Earth News

Dragonfly species pseudagrion microcephalum
The Malaysian dragonfly Pseudagrion microcephalum. (K. Wilson)

At least one in ten species of dragonfly and damselfly are threatened with extinction, according to the first world survey of their numbers.

The figure may be an underestimate as so little is known about many species.

However, the news is not all bad. The survey published in Biological Conservation is the first to assess the vulnerability of any insect group on a global scale.

And it suggests the extinction risk faced by insects has been exaggerated.

31% of amphibians
20% of mammals
12% of birds
10% of dragonflies and damselflies

Viola Clausnitzer led an international team of conservation scientists from Germany, Australia, Japan, Russia and the UK among others. They reviewed the status of a random sample of 1500 of the 5680 dragonflies and damselflies known to science.

The team assessed the population and distribution of each species according to the Red List criteria set down by the World Conservation Union (IUCN).

They found that more than half of the species should be categorised as Least Concern, which means they likely remain widespread globally, or are not threatened even if they live in a restricted range.

But one in 10 species is threatened, meaning it is categorised as critically endangered, endangered or vulnerable.

Pemba Featherleg (Platycnemis pembipes)
The Pemba Featherleg (Platycnemis pembipes) a fragile damselfly first discovered in 2001. The species inhabits a single stream in Tanzania and is listed as Critically Endangered. (V. Clausnitzer)

"It's fair to say that is an underestimate," says Clausnitzer, as too little data exists to accurately assess the status of 35 per cent of the species.

Dragonflies and damselflies, which belong to the insect order known as the Odonata, are susceptible because the larvae of each species live in water. So pollution and changes to habitat, such as forest degradation, which affect water courses can have an impact.

Indeed, because of their sensitivity to water and habitat quality, dragonflies are frequently used to assess environmental health. With their striking colours and behaviour they can be used as indicator species. "If they disappear you've got something wrong with your habitat," says Clausnitzer.

Those species most at risk tend to live in south east Asia and Australia.

In south east Asia, a large number of species are endemic to islands such as the Philippines or within Indonesia, and cannot escape detrimental impacts on their habitat.

Two species of Odonata are known to have gone extinct
Both lived on islands
Sympetrum dilatatum once lived on Saint Helena
Megalagrion jugorum once lived on Maui in the Hawaiian islands

In Australia, climate change is having an especially strong impact on freshwater systems.

The survey is the first to assess the global health of any order of insects. Compared to vertebrates, the dragonflies and damselflies are not doing badly.

"Amphibians are more threatened than dragonflies in general," says Clausnitzer. Amphibians are being particularly afflicted by the deadly chytrid fungus. "Another difference is that adult dragonflies are more mobile. If one site is destroyed they still have the chance to fly to another site, which frogs don't have."

They also seem less to be less threatened than the mammals, but at a similar level of risk as birds.

"We were a bit surprised that the dragonflies are not that bad off," says Clausnitzer.

"There is a big discussion going on about invertebrates and extinction rates in insects, and this discussion is not based on any real figures. It is all estimations," she adds.

Klugi's Threadtail
Only males of Klugi's Threadtail (Protoneura klugi) were known from two locations in Amazonian Peru. The species is listed as Data deficient. (R. W. Garrison)

In general, conservationists have feared that a much higher proportion of insect species face extinction.

However, Clausnitzer cautions that much more research needs to be done to be sure, and different groups of insects might face very different challenges.

For instance, while the reliance of dragonflies and damselflies on water makes them susceptible, says Clausnitzer "dragonflies are the strongest fliers in the insect kingdom. So you might get a very different picture if you take less capable fliers."


Wednesday, July 15, 2009

Longest insect migration revealed

Matt Walker
Editor, Earth News

Globe skimmers (Pantala flavescens)
Globe skimmers rest up

Every year, millions of dragonflies fly thousands of kilometres across the sea from southern India to Africa.

So says a biologist in the Maldives, who claims to have discovered the longest migration of any insect.

If confirmed, the mass exodus would be the first known insect migration across open ocean water.

It would also dwarf the famous trip taken each year by Monarch butterflies, which fly just half the distance across the Americas.

Biologist Charles Anderson has published details of the mass migration in the Journal of Tropical Ecology.

Each year, millions of dragonflies arrive on the Maldive Islands, an event which is well known to people living there.

"But no-one I have spoken to knew where they came from," says Anderson, an independent biologist who usually works with organisations such as the Maldivian Marine Research Centre to survey marine life around the islands.

This just illustrates how little we still know about the natural world
Biologist Charles Anderson

Their appearance is especially peculiar because the 1200 islands that make up the Maldives lie 500 to 1000km from the mainland of southern India, and all are coral cays with almost no surface freshwater, which dragonflies need to complete their lifecycle.

Anderson noticed the dragonflies after he first arrived in the Maldives in 1983. He started keeping detailed records each year from 1996 and now collates data collected by local observers at other localities in the Maldives, in India and on vessels at sea.

When Anderson compared these observations with those made of dragonflies appearing in southern India, he found a clear progression of arrival dates from north to south, with dragonflies arriving first in southern India, then in the Republic of Maldives' capital Male, and then on more southern atolls.

Each year, dragonflies first appear in Male between 4 and 23 October, with a mean arrival date of 21 October. Dragonfly numbers peak in November and December, before the insects then disappear once more. The insects arrive in waves, with each staying for no more than a few days.

Over 98% of the dragonflies recorded on the islands are Globe skimmers (Pantala flavescens), but Pale-spotted emperors (Anax guttatus), Vagrant emperors (A. ephippiger), Twisters (Tholymis tillarga) and Blue perchers (Diplacodes trivialis) also appear in some numbers.

The dragonflies then reappear between April and June.

Longest journey

The dragonflies are clearly migrating from India across the open sea to the Maldives, says Anderson.

"That by itself is fairly amazing, as it involves a journey of 600 to 800km across the ocean," he says.

Quite how they do it was a bit of a mystery, as in October at least they appear to be flying against the prevailing winds.

However, in October, and continuing into November and December, a weather system called the Inter-tropical Convergence Zone moves southwards over the Maldives.

Ahead of the ITCZ the wind blows towards India, but above and behind it the winds blow from India. So it seems that the dragonflies are able to reach Maldives by flying on these winds at altitude above 1000m.

Globe skimmers are renowned for their ability to fly long-distances
They can fly up to 6300m high, the highest of any dragonfly species
With a tailwind of 10m per second, a dragonfly could cross from India to Male in 24 hours
Maldivians consider the dragonflies' arrival to be a harbinger of the north-east monsoon

But that is not the end of the animals' epic adventure.

"As there is no freshwater in Maldives for dragonflies, what are they doing here?" asks Anderson.

"I have also deduced that they are flying all the way across the western Indian Ocean to East Africa."

Anderson has gathered a wealth of circumstantial evidence to back his claim.

Large numbers of dragonflies also start appearing in the northern Seychelles, some 2700km from India, in November, and then in Aldabra in the Seychelles, 3800km from India, in December.

That matches the slow southerly movement of the Inter-tropical Convergence Zone weather system, behind which winds blow steadily from India to East Africa.

It is also known that Globe skimmers appear in large numbers through eastern and southern Africa.

In Uganda, they appear twice each year in March or April and again in September, while further south in Tanzania and Mozambique they appear in December and January.

Record breakers

That strongly suggest that the dragonflies take advantage of the moving weather systems and monsoon rains to complete an epic migration from southern India to east and southern Africa, and then likely back again, a round trip of 14,000 to 18,000km.

"The species involved breeds in temporary rainwater pools. So it is following the rains, taking sequential advantage of the monsoon rains of India, the short rains of East Africa, the summer rains of southern Africa, the long rains of East Africa, and then back to India for the next monsoon," says Anderson.

"It may seem remarkable that such a massive migration has gone unnoticed until now. But this just illustrates how little we still know about the natural world."

The monarch butterfly is often cited as having the longest migration of any insect, covering around 7000km in an annual round trip from Mexico to southern Canada.

On average, it takes four generations of butterflies to complete the journey.

Anderson believes that the dragonflies survive the ocean flights by gliding on the winds, feeding on other small insects.

They too, take four generations to make the full round trip each year.

He says the migratory paths of a number of insect-eating bird species, including cuckoos, nightjars, falcons and bee-eaters, follow that of the dragonfly migration, from southern India to their wintering grounds in Africa. That suggests the birds feed on the dragonflies as they travel.

"They [fly] at the same time and altitudes as the dragonflies. And what has not been realised before is that all are medium-sized birds that eat insects, insects the size of dragonflies," he says.

Extraordinary ability

"There are earlier records of swarms of Globe skimmers flying out to sea, and at sea," Anderson continues.

"But it was always assumed that those dragonflies were doomed. Which says rather more about our earth-bound lack of imagination than it does about the globe skimmers' extraordinary flying abilities."


Thursday, July 9, 2009

Spider builds life-sized decoys

Matt Walker
Editor, Earth News

C. mulmeinensis with decoys of itself
An adult C. mulmeinensis alongside decoy prey pellets (L) and decoy egg sacs (R)

There is a species of spider that builds models of itself, which it uses as decoys to distract predators.

The spider may be the first example of an animal building a life-size replica of its own body.

So believe the scientists who made the discovery, which is published in the journal Animal Behaviour.

The arachnid's behaviour also offers one explanation for why many spiders like to decorate their webs with strange-looking ornaments.

Many animals try to divert the attentions of predators by becoming masters of disguise.

Some try to avoid being seen altogether by using camouflage to blend in against a background, such as the peppered moth evolving motley wings that blend into tree bark, or stick insects that look like sticks.

Others evolve more conspicuous ornaments designed to distract a predator, such as butterflies that grow large eyespots or lizards that quickly move colourful tails, which they detach from their bodies if grabbed.

This latter strategy has puzzled biologists, because attracting predators in the first place is usually a bad idea.

One hypothesis is that animals which grow conspicuous ornaments benefit overall, because directing a predator to attack an expendable part of the body, such as the lizard's tail, outweighs the costs of attracting the attention of the predator in the first place.

Under attack

But animals do not tend to actually build life-like replica models of themselves to act as decoys.

However, that is exactly what a species of orb spider called Cyclosa mulmeinensis does, biologists Ling Tseng and I-Min Tso of Tunghai University in Taichung, Taiwan, have discovered.

This and other related spiders in the same genus decorate their webs with material such as detritus, plant parts, prey remains or egg sacs.

Because such detritus is often of a similar colour to the spider, researchers suspected it might help camouflage the arachnid.

Our study seems to be the first to empirically demonstrate the function of animal-made decoys
Spider specialist I-Min Tso

Initially Tseng and Tso decided to test the idea by videoing another related species called Cyclosa confusa living in the wild. They measured how often predatory wasps attacked the spiders in webs decorated with detritus compared with those in undecorated webs.

"We predicted that spiders with prey carcass decorations on webs should receive fewer wasp attacks because spiders should be well camouflaged by such objects," says Tso. "To our surprise, spiders on decorated webs received far more attacks than those on undecorated webs."

That confirmed that the decorations attracted predators rather than acting as camouflage.

However, Tseng and Tso suspected that these decorations might also redirect enough attacks to make them worthwhile.

Life-like decoys

So they tested the idea on another species Cyclosa mulmeinensis living on Orchid Island off the southeast coast of Taiwan. This species decorates its web with both the remains of dead insect prey and egg sacs.

Intriguingly, the spiders made prey pellets and egg sacs that were the same size as its own body.

The researchers also found that these decorations appeared to wasps to be the same colour, and reflect light in the same way, as the spider's body.

In short, the spider made decorations that were of the same size, shape and appearance as itself.

"Our results show that this vulnerable spider protects itself from predator attacks by constructing decoys that increase the conspicuousness of the web, and resemble its own appearance in size and colour," the researchers write in Animal Behaviour.

Female C. mulmeinensis
A female C. mulmeinensis

"When both spiders and web decorations are present on the same web, they look like a string of nearly identical oval objects to the predators."

"I don't know of any animal that actively builds a decoy of itself. Our study seems to be the first to empirically demonstrate the function of animal-made decoys," says Tso.

The decoys worked, too. More often than not, a wasp would attack a decoy rather than the spider, thinking it to be a tasty meal.

But all wasp strikes on spiders living on undecorated webs were directed straight at the spider.

"Decorations built by Cyclosa spiders function as a conspicuous anti-predator device instead of a camouflaging device. The benefit of successful escape from predator attack seems to outweigh the cost of increased detection," says Tso.

Web decorations

Scientists have been trying to answer the question of why many species decorate their webs for more than 100 years.

Tso suspects that there is no single answer.

"I think that the functions of web decorations might be very diverse and differ from taxa to taxa. Different spiders seem to decorate their webs for different reasons," he says.

For example, spiders often decorate their webs with silk ornaments, which might strengthen the web, act as a warning signal to predators, to deter large animals from accidentally walking into the web, destroying it, or to act as a visual signal to attract prey.

Others, including Cyclosa species, may use non-silk decorations primarily as anti-predator devices.


Wednesday, July 8, 2009

Lizards in an Evolutionary Tree

Jonathan B. Losos

Lizards in an Evolutionary Tree

Ecology and Adaptive Radiation of Anoles

Foreword by Harry W. Greene

Cover Image

Adaptive radiation, which results when a single ancestral species gives rise to many descendants, each adapted to a different part of the environment, is possibly the single most important source of biological diversity in the living world. One of the best-studied examples involves Caribbean Anolis lizards. With about 400 species, Anolishas played an important role in the development of ecological theory and has become a model system exemplifying the integration of ecological, evolutionary, and behavioral studies to understand evolutionary diversification. This major work, written by one of the best-known investigators of Anolis, reviews and synthesizes an immense literature. Jonathan B. Losos illustrates how different scientific approaches to the questions of adaptation and diversification can be integrated and examines evolutionary and ecological questions of interest to a broad range of biologists.


Monday, July 6, 2009

No insurance cover for sarpa mitras

5 Jul 2009, 0512 hrs IST, Vijay Pinjarkar, TNN

Sarpa mitras' (snake friends) have blamed forest minister Babanrao Pachpute for not fulfilling his promise to recognise them by issuing I-cards and also providing insurance cover.

Last year, at a sarpa mitra parishad' organised by the forest department in Aurangabad, Pachpute had promised to issue I-cards to sarpa mitras' and also insurance cover. Several meetings of top officials were also held with the minister on the issue to discuss modalities but the snake friends have failed to get their due.

The issue assumes significance, especially when snakes have started surfacing with the onset of monsoon. The snake friends have been attending frantic calls to rescue reptiles who at times threaten the lives of residents and also get killed at the hands of the irate crowd or dwellers. Last year, over 1,000 rescued snakes were released by the forest department. Snake bites claimed two lives in the city. The victims included standard VII student Jaspreet Randhawa of Ramai Nagar and rickshaw puller Sanjay Nikhade, who was bitten by a Russell's Viper on WHC Road on Monday. Nikhade succumbed to his injuries at GMCH on Thursday.

On Thursday morning, one more deadly Russell's Viper was rescued by sarpa mitra' Laxmikant Harkare from Prakriti' premises, an NGO working for women's development at Lonara near Nagpur. The snake did not harm anyone and was released by forest guards Kishore Kadwe and Harkare.

"Genuine snake friends need to get a better deal as they are working for a noble cause. The problem is that most of them are unemployed and have to spend from their pockets on phone calls and petrol. The forest department too doesn't have vehicles and staff to handle such emergencies. Besides, there is a lot of paper work involved," said Harkare.

Sarpa mitra' Bhuvan Patel of Dahegaon on Saoner Road too supports Harkare. He said in the past 15 days, their group has released around 100 snakes in Khapa forest. "We do it out of interest in wildlife and not for money but the forest minister has not kept his promise of issuing even I -cards, forget insurance cover," Patel said.

Last year, around 30 sarpa mitras' had come under one roof on the initiative taken by the Nagpur forest division. Conservationist Kundan Hate and Maharajbagh zoo incharge Dr S S Bawaskar had worked to unite sarpa mitras' but the move fizzled out.

Hate blamed snake friends for the mess. He said that they did not unite for the cause thinking their importance will diminish if they joined hands. Besides, those who were not trained also applied for I-cards leading to chaos. Hate agreed that genuine snake friends need to be recognised and given insurance cover. The government needs to act fast.

PCCF C S Joshi was not aware of the issue of I-cards to sarpa mitras'. N Rambabu, conservator of forests (CF), Nagpur division, promised to issue I-cards to sarpa mitras'. He said providing insurance cover is something which is not in his hands and will be decided at the government level.

Saturday, July 4, 2009

Europe's pollen bees and wild flowers caught up in a vicious cycle of decline

By Steve Connor, Science Editor
Friday, 21 July 2006

Bees and the wild flowers they pollinate have declined significantly across large tracts of northern Europe, according to one of the most comprehensive surveys of pollinating insects.

Scientists examined hundreds of wildflower sites in Britain, the Netherlands and Germany and found the diversity of bees has fallen in 80 per cent of them over the past 25 years.

The researchers said wildflowers that rely on specialist species of bees for pollination have also declined, suggesting the two are caught up in a vicious cycle of decline.

The authors of the report, in the journal Science, believe intensive farming and pesticides, as well as the loss of wild habitats, may be helping cause the widespread fall in the diversity of bees and wildflowers.

"We were shocked by the decline in plants as well as bees," said Dr Koos Biesmeijer, a researcher at the University of Leeds. "If this pattern is replicated elsewhere, the pollinator services we take for granted could be at risk, and with it the future of the plants we enjoy in our countryside.

"Whatever the cause, the study provides a worrying suggestion that declines in some species may trigger a cascade of local extinctions amongst associated species."

Bees and other nectar-loving insects such as hoverflies are essential for pollinating many plants, including commercially important crops. Globally, the economic value of pollination is thought to be worth between £20bn and £50bn a year.

In Britain, where bee diversity has fallen and hoverfly numbers have held steady, the amount of wildflowers that require insects for pollination has declined by 70 per cent, but the number of wind-pollinated plants or those that self-pollinate have remained steady or increased.

The scientists found a slightly different pattern in the Netherlands where bees have, on average, declined but hoverfly diversity has increased. Here, there has been a decline in wildflowers that rely on bees for pollination, but not in other plant species that make use of other insect pollinators.

Raul Ohlemüller, a member of the research team at the University of York, said the difference between the two countries suggests there is a causal link between the decline of bees and plants. "The parallel declines of wildflowers and their pollinators seem too strong to be a coincidence," Dr Ohlemüller said.

Bill Kunin, co-ordinator of the project from Leeds University, said: "We looked at plant changes as an afterthought, and were surprised to see how strong the trends were. When we contacted our Dutch colleagues, we found they had begun spotting similar shifts in their wildflowers as well."

Another example of a bee in trouble is the field scabious bee, Andrena hattorfiana, which raises its young on the pollen of the field scabious flower. The study found both the bee and the flower have gone into decline in Britain and the Netherlands, which may be partly caused by grazing and early cutting of hay meadows which prevent the plant from flowering.

As the plant has fallen in numbers, this has had a knock-on effect on the bee, whose declining numbers may have added to the flower's problems of how to produce viable seeds.

Yet another example of bees in decline are the longhorn bees, which have all but disappeared in many parts of Britain and the Netherlands, possibly because of a parallel decline in the wild peas that were once cultivated widely as animal fodder.

Stuart Roberts, of the University of Reading, said: "Here in Britain, pollinator species that were relatively rare in the past have tended to become rarer still, and the commoner species have become even more plentiful. Even in insects, the rich get richer and the poor get poorer."


The Independent