Cull ‘cannot save’ Tasmanian devil

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Culling does not effectively control the contagious cancer threatening the Tasmanian devil, a new study suggests.

The researchers modelled the effect of removing sick animals on the disease’s prevalence in a small population.

The study, in the Journal of Applied Ecology, seems to confirm findings in wild trials, that selective culling of sick animals is ineffectual at stopping the spread of the disease.

All trial culls of the devils have now been stopped.

Culling has been used to control infectious diseases in a range of species from deer to badgers, wolves to domestic cattle.

Despite proving successful in controlling the diseases of livestock, such as foot and mouth, culling wild animals is controversial because of the lack of evidence that it works.

In fact, cases exists where culling wild animals has made the problem worse.

But, hoping to save the Tasmanian devil, Sarcophilus harrisii, from the facial cancer that has wiped out more than 90% of individuals in some areas, conservation biologists have trialled a cull since 2004.

Costly cull

As part of the trial cull, researchers have trapped and euthanised sick animals two to five times a year from an isolated population in the south-east of Tasmania.

Each year, the project costs more than $200,000 (£122,000). Critics say this money could otherwise be spent on captive breeding programmes.

To assess the impact of the cull, Australian researchers Nick Beeton from University of Tasmania and Hamish McCallum from Griffith University created a computer model in which they simulated the effects of the cull.

“We found the removal rate required to suppress disease was higher than that which would be feasible in the field,” explained Mr Beeton.

In the field, biologists find that 20% of the population is never captured and could be acting as a reservoir for the disease.

Unless all the devils are trapped and inspected, including the “trap-shy” ones, continuous culling is unlikely to be an effective disease control, the researchers write.

Mr Beeton told BBC News: “The disease suppression trial was ended as this paper was being written.”

“Our research demonstrates that we must be flexible and be prepared to change strategy as new information comes to light,” he added.

“It’s much better to do a study like this, than spend a lot of money on a huge culling programme and then find that it hasn’t worked,” said geneticist Elizabeth Murchison from the Welcome Trust Sanger Institute in Hinxton, UK, who studies the devil cancer.

She added that by confirming that culling does not work, conservationists can then focus their efforts on alternative strategies, such as the captive breeding programme and developing a vaccine against the cancer.

The transmissible facial cancer

  • Devil Facial Tumour Disease (DFTD) is spread by biting during aggressive encounters
  • The living cancer exists as contagious clone cells; highly unusual for a cancer. There is only one other transmissible cancer known, which affects dog genitals
  • The devil’s immune system seems unable to detect the cancer
  • The disease forms tumours around the mouth interfering with feeding, leading to death
  • The cancer originally arose in Schwann cells – cells which wrap themselves around nerve tissue
  • First seen in 1996, the cancer has badly hit Tasmanian devil populations

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UK invests in graphene technology

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The UK government has pledged £50m towards developing spin-off technologies from the super-strong material graphene.

The announcement comes exactly a year after two Manchester-based scientists were awarded the Nobel-prize for its discovery.

The money is hoped to give researchers more bench space to explore the material’s commercial potential.

Funds will be available in the next few months, said the UK science minister.

Graphene, the “miracle material” of the 21st Century, is so far the strongest material known to science, and better at conducting electricity than copper.

It could have a large number of potential application; scientists say it could find uses from transparent touch screens to solar cells, from aircraft wings to optical communication systems, like broadband.

The Chancellor, George Osborne, in his speech at the Conservative Party conference said: “…We will fund a national research programme that will take this Nobel Prize-winning discovery from the British laboratory to the British factory floor.

“We’ve got to get Britain making things again.

“Countries like Singapore, Korea, America are luring [researchers] with lucrative offers to move their research overseas,” he added.

The funds for graphene R&D are in addition to £145 million “earmarked” for the establishment of more UK-based supercomputers, along with funding to support more computer-scientists and facilities to house them, the University and Science Minister David Willetts told BBC News.

He said: “I’m very happy; even in tough times we are investing in science”.

In response to the announcement, Professor Sir Peter Knight, President of the Institute of Physics, said: “We’re delighted that the Government recognises the role science can play in creating a vibrant, diverse economy for the future of the UK – investment in science delivers great returns economically and intellectually”.

“We applauded the Government’s decision to ‘invest intelligently’,” said the director of the Campaign for Science and Engineering (Case) Imran Khan in a statement.

However, he cautions: “These new investments are coming in the wake of enormous cuts to the nation’s science and engineering base.

“Last month [Case] released an analysis showing that £1.7bn will have been cut from research and development funds by 2014-15.”

Without a long-term strategy to put science and engineering at the heart of the UK’s economic recovery, said Mr Khan, home-growth discoveries like groundbreaking research into graphene could be a thing of the past.

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Flowers bloom for a second time this year

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UK plants are flowering for a second time this year because of the unseasonably warm weather.

With temperatures soaring, plants such as foxglove and cowslip, which usually flower in the spring, are in full bloom six to eight months early.

Cold nights experienced across the UK in August are thought to have led to the early onset of autumn colours.

This warmer spell now has plants acting like it is spring.

Gardeners at the Kew’s Wakehurst Place gardens in Sussex said they are working from a “new rule book” to keep up.

“It is a very unsual year…I’ve been gardening for 30 years and have never seen anything like this,” said Wakehurst Place’s head Andy Jackson.

“We are increasingly seeing that plants are not synchronised with what the weather is doing,” he added.

In the last year, the UK experienced a severe drought, then lots of rainfall and a cold snap in the summer, all before this warm spell explained Mr Jackson.

From mid-August, gardeners were seeing trees turning yellow and orange; it is unclear what will happen now with temperatures reaching into the thirties (eighties) in parts of the South, East and the Midlands.

The BBC’s meteorologist Liam Dutton explained that the position of the jet stream north of the UK has allowed high pressure to build, bringing in the very warm air from western Europe.

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Fish shrinkage probed in lab

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Scientists are starting a novel project to investigate whether overfishing alters fish behaviour and changes their pattern of development.

Overexploitation of stocks has already been shown to select for smaller fish.

A team reporting at the meeting of the European Society for Evolutionary Biology in Germany will deliberately remove the largest individuals from populations of lab-bred guppies.

The experiment is designed to uncover what is happening in our oceans.

“There are clear indications that almost all… commercial fish are shrinking,” said marine biologist Carl Lundin, who directs the International Union for the Conservation of Nature’s Global Marine and Polar Program.

For mass spawning fish such as cod, there is a great advantage to maintaining older, larger females because they are very efficient at restocking the population.

And if industrial fishing selectively removes the largest individuals, explained Dr Lundin, the industry suffers as populations are reduced to the smallest fish.

However, smaller seafood is unlikely to be the only consequence of industrial fishing; research has also shown that fish in the oceans are reproducing earlier.

Experimental evolution

Now evolutionary biologist Beatriz Diaz Pauli and her colleagues from the University of Bergen, Norway have begun an experiment that they hope will help uncover what other changes we can expect to see in the oceans’ fishes.

The team established nine populations of guppies, each comprising 500 to 900 individuals. Over the next few years, Ms Diaz plans to remove all the fish that measure over 16mm from three of her tanks.

In the remaining tanks, Ms Diaz will purge fish under 16mm, or take fish independent of their size – regimens that will act as a control for the effects of changing the density of fish in the tanks.

The team will then painstakingly record the changes that they see in the fish’s growth rate, age and size of maturation, reproductive effort, and mating and feeding behaviours.

The team hopes to unpick whether the shifts they see are a result of fish moulding themselves to a new environment – a so-called plastic response – or are a consequence of genetic changes.

Plastic responses are not inherited. For example, an organism might reach a smaller body size if it gets little food as a juvenile, but its young would not inherit this propensity to be small.

Genetic responses, by contrast, are inherited, and even if a future generation is returned to an environment where food is plentiful, it would remain small.

Determining the nature of the changes in the fish will help scientists understand how stocks might recover if overexploitation stopped or breeding grounds were protected.

“If we set aside 20-30% of the habitat where reproduction… of key commercial fish stocks [occurs], we are much more likely to avoid these types of problems,” said Dr Lundin.

He added that carrying out experiments of this type allows researchers to control other factors that could affect the fishes’ survival and concentrate on just the consequences of overexploitation.

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The EcoIsland

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The UK’s energy prices are soaring. As gas and oil reserves run dry, the cost of energy will continue to climb. But what if we could wean ourselves off fossil fuels and make the jump to clean, renewable energy?

This is exactly what a small island off the coast of Africa plans to do. With a population of 11,000 people, El Hierro is building a solution to its mounting energy costs. As the most remote Canary Island, it struggles to meet the high price of shipping oil from the mainland. But what the island lacks in fossil fuels it makes up for in wind – over 3,000 hours a year of gusts blowing fast enough to propel windmills and generate
electricity.

And on the rare windless day, El Hierro hopes to bridge the gaps in its electricity supply with the ultimate energy cache: a 500,000m cubed reservoir some 700m up inside the island’s dormant volcano. When the power supply dwindles, the reservoir
can be drained downhill through turbines to generate electricity.

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Is It Folly to Take Folic Acid?

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For mothers-to-be, doctors worldwide advise taking a folic acid supplement. That’s because pregnant women with a deficiency of this vitamin have an increased chance of giving birth to a baby with serious birth defects, such as spina bifida and anencephaly. Yet a new mouse study shows that folic acid supplementation can itself sometimes increase the risk of birth defects or even cause the death of embryos. Experts caution, however, that the unexpected rodent results are too preliminary to require an immediate change in medical practices until more is known about how the vitamin influences development.

People typically obtain folic acid, or folate, from consuming leafy vegetables, but not everyone gets enough from their diet, particularly pregnant women. The vitamin plays a key role in the development of the neural tube, the embryonic region that gives rise to the spinal cord and brain.

Evidence from randomized clinical trials has shown that babies born to women who double their recommended daily dose of folic acid are between 40% and 50% less likely to have birth defects of the spine, skull, and brain. As a result, the United States has fortified most of its grains with this vitamin since 1998, and a handful of other countries have followed suit.

But just how the vitamin influences embryonic growth remains a mystery. So developmental biologist Lee Niswander of the University of Colorado, Denver, set out to investigate folic acid supplementation in mice genetically predisposed to giving birth to embryos with neural tube defects. She and her colleagues fed five such strains of mutant mice food containing either 2 or 10 mg of folic acid per kilogram, which created a range of blood levels of the vitamin equivalent to that in the U.S. population.

To the surprise of the researchers, in three of the five strains, the extra folic acid seemed to worsen the severity of birth defects rather than remedy them. In one of the mutant lines, dubbed L3P, eating the higher folic acid diet long term increased the chance that young were born with neural tube defects from 20% to 60%, the group reports in the 15 September issue of Human Molecular Genetics. And for another strain, Shroom3, many of whose embryos don’t naturally survive until birth due to their genetic problems, eating the higher folic acid food significantly increased the percentage of lost embryos.

Niswander says it is clear that folic acid is good for human fetuses, but the new study makes her wonder whether high levels of the vitamin may be harmful in some circumstances. Still, she stresses that more data are needed before any serious reconsideration of how much folic acid to recommend for impending mothers.

Roy Pitkin, a retired University of California, Los Angeles, researcher who specialized in pregnant women’s nutrition and chaired an Institute of Medicine panel that in 2000 reviewed folic acid’s health effects also cautions against a rush to judgment: “It would really be throwing the baby out with the bath water to say that because of this one mouse study, we are going to question the food fortification.”

Especially, he says, because we know that species differ considerably from each other when it comes to birth defects. He offers the example of thalidomide—a drug given to pregnant women in the 1950s to cure morning sickness—that causes severe human birth defects but that is perfectly safe in rats.

Neuroscientist Elizabeth Grove of the University of Chicago studies how the mammalian brain develops and echoes this concern. She warns that researchers have found hundreds of mutations that cause birth defects in mice but that so far don’t seem to produce the same problems in humans. The effects of folic acid may also be species specific, she says.

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Plant has evolved a specialist bird perch

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New research sheds light on the world’s most specialised bird perch.

The researchers suspect that the vertical, branchless stem of a South African plant – locally called the Rat’s Tail – has evolved to encourage pollinating birds to visit its flowers.

The birds hang upside down from this perch and fertilise the plant when they thrust their beaks into the red flowers to drink nectar.

The international team reports the findings in the Annals of Botany.

Plants go to great lengths to attract animals to pollinate them; they seduce insects, birds and small mammals with colourful, shapely, sweet-smelling flowers.

Some plants even wave at passing pollinators.

On first seeing the deep red, long-tubular flowers of Babiana ringens in 2003, botanist Spencer Barrett from the University of Toronto, Canada, suspected that he was dealing with a plant that was pollinated exclusively by birds.

But the position of the flowers at the base of the plant perplexed him.

Most birds avoid feeding on or close to the ground to keep clear of ground-dwelling predators; plants reliant on bird-pollination tend to keep their flowers up high.

Dr Barrett and his colleague Bruce Anderson from University of Stellenbosch in South Africa, wondered if the curious perch-like structure had evolved to give pollinating birds a foothold from which to feed.

Crouching among the shrubs of the Cape of South Africa, binoculars in hand, Dr Barrett and his team confirmed that the flowers were exclusively pollinated by sunbirds.

“When we saw a bird visiting we were completely enchanted,” said Dr Barrett.

Relaxed selection

Still unconvinced that the stick-like protrusion had evolved as a perch, the team set about to gather further evidence.

They set out to look at the full distribution of B. ringens across the Cape, and found that in the east, where sunbirds have a greater variety of flowering plants to choose between, B. ringens‘ perches were smaller than in the west, where plants can rely on regular visits from sunbirds.

Dr Barrett suspects that in the absence of pollinating birds, the plants do not need to invest in maintaining the perch, and so it shrinks over many generations – an example of what is called relaxed selection.

With time, this branch might return to its ancestral form, which the researchers suspect was a central stem with flowers at its top, much like many of B. ringens’close relatives.

“It’s a fascinating piece of work,” said plant biologist Professor Simon Hiscock from the University of Bristol.

This study poses questions about the influence of pollinators on the structures of flowers and on plants’ reproductive strategies, he added.

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Waving robotic crab arm attracts females

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A vigorous wave of the claw can be the key to mating success for male fiddler crabs, report researchers at the 13th Congress of the European Society for Evolutionary Biology.

Male crabs advertise their quality as a potential mate to passing females by waving their large yellow claws.

Using robotic arms, researchers evaluated how the size and speed of the waving claw affected mating success.

The results may help explain why males protect their smaller neighbours.

To the fiddler crab Uca mjoebergi, the Australian mudflats in the north of the country are a heaving dance floor, where a male must rely on his moves to attract a mate.

Males stand outside their burrows and use their enlarged claw to attract females by moving it in circles.

If a female likes the look of a male, she will come closer and disappear down his burrow in the sand, possibly staying to mate.

Wave of waving

When a female wanders through a neighbourhood, “you see part of the mudflat light up” with waving yellow claws, said ecologist Sophie Callander from the Australian National University in Canberra.

Dr Callander and her colleagues used a fully adjustable robotic arm – called Robocrab – to determine what female crabs are looking for in a mate.

Dr Callander set up three robotic arms around a female crab, and sat beneath the unforgiving Australian sun for many hours recording the females’ reactions to different combinations of wave speeds and claw size.

Females approaching from 20cm preferred males with a higher wave rate and larger claws. Intriguingly, this preference increased in strength when the male was flanked by more slowly waving, smaller-clawed crabs.

Fiddler crabs also use these claws in displays of dominance and fighting prowess.

Previous work has shown that larger males sometimes go to the aid of smaller males when an intruder is trying to steal a smaller male’s burrow.

This behaviour is unlikely to be an altruistic form of neighbourhood watch, and Dr Callander thinks that her experiment could offer an explanation.

“If larger males can retain smaller neighbours they might… increase their mating success,” she told BBC News.

For fiddler crabs at least, it pays to keep close to the small and weak.

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Bed bugs protect their sperm from bacteria

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Bed bugs protect their sperm against sexually transmitted infections by producing germ-busting ejaculates, scientists have found.

Bacteria covering bed bugs’ bodies are transmitted to the female, along with the sperm, during mating.

The new work shows that without the protection of antibacterial agents in the bug’s ejaculate, 40% of sperm die.

The results were presented at the 13th Congress of the European Society for Evolutionary Biology.

Bed bugs, and the related bat bugs that live in African caves, are renowned for their bizarre sex lives.

‘Traumatic insemination’

Males, instead of penetrating the female’s vagina, pierce her underside and deposit sperm inside the female, where it swims through the insect’s blood system to the ovaries to fertilise the eggs.

Female bed bugs protect themselves against the diseases that males transmit with a structure on their bellies that guides the penis into a mass of germ-fighting cells.

Males, it seems, have also evolved a way to fend off the effects of sexually transmitted infections, evolutionary biologist Oliver Otti from the University of Sheffield, UK, told conference attendees in Germany.

Suspecting that males load their ejaculates with proteins that protect sperm, Dr Otti carefully extracted sperm from a number of male bed bugs, being sure not to mix it with the seminal fluid that usually makes up the rest of the ejaculate.

He then mixed the sperm with a “soup” of micro-organisms that he had collected from the outer skin of the bed bugs.

To half of these samples he added lysozyme, a bacteria-killing enzyme known to be active in bed bugs, and saw that 40% more sperm survived in its presence.

Females didn’t gain any protection from these introduced bacteria-busting enzymes, he explained; the presence of lysozyme in the ejaculate seemed to be purely to protect sperm.

But other work by Dr Otti’s colleague Michael Siva-Jothy, who is also based at the University of Sheffield, shows that females protect themselves from the infections introduced during sex with their own lysozymes.

In fact, females ramp up their lysozyme activity just before they are about to feed. Dr Siva-Jothy explained that this is probably because in the bed bug world, feeding is generally always followed by mating.

“Wounding is a very frequent event during and after copulation, and generally genitals are not that clean, ” Dr Otti told BBC News.

He explained that the research that has focused on human sexual transmitted diseases has tended to ignore the microbes that coexist with us on our skin; these microbes are likely also transferred during sex.

“It is not clear what the cost of having them around is,” Dr Otti added.

The advantage of studying bed bugs, he said, is that we share many components of our immune system. As a result, scientists can learn much from manipulating the bugs’ sex lives to study the consequences on lifespan and offspring production – some of these trade-offs could be relevant to humans.

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