Scientists discover lizards on verge of leap from egg-laying to live births

Scientists have caught the process of evolution in action as a species of Australian lizard abandons egg-laying for live births. The variety of skink, which is snake-like with four tiny legs, has been found laying eggs along the coast of New South Wales. However, the same yellow-bellied three-toed lizard living in the colder mountainous region is giving birth to offspring like a mammal does.

Rare study: The Australian lizard has been found laying eggs along the warm coast of New South Wales while the same species gives birth to live young in the colder mountainous region 

There are only two other types of modern reptiles which use both types of reproduction methods – another skink species and a European lizard.One in five snakes and lizards gives birth to live young, with records showing nearly a hundred reptile lineages have changed from egg-laying in the past.

Study co-author James Stewart, a biologist at East Tennessee State University, in America, told National Geographic that the discovery provided scientists with a rare opportunity. ‘By studying differences among populations that are in different stages of this process, you can begin to put together what looks like the transition from one [birth style] to the other,’ he said. Mr Stewart said the transformation could be linked to how newborns get nourishment. Or it could be a way of protecting the young in harsher climates.

Baby mammals are fed via a placenta which is connects the foetus to the ovary wall. Through this it can breathe and pass back waste. Embryos of egg-laying species get nutrients from the yolk while absorbing calcium from the porous shell, which also protects them from the external environment.However, some fish and reptiles are using a mix of both birthing styles.

Mothers form an egg which she keeps inside her body until the last stages. The shells thin, allowing the embryos to breathe until birth – but, according to scientists, this poses a nourishment problem, as it contains less calcium. This discovery prompted Mr Stewart and his colleagues to investigate the nutrient issue in the structure and the chemistry of the Australian lizard’s uterus.

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Butterflies, moths get barcode treatment

Canadian researchers are 'barcoding' Australia's moths and butterflies as part of a project to comprehensively map the planet's biodiversity.

In the last 10 weeks a team from the University of Guelph in Ontario, Canada, has successfully 'barcoded' 28,000 moth and butterfly specimens from the CSIRO's Australian National Insect Collection (ANIC). That covers around 6500 of Australia's 10,000 known species.

The Canadian team proposed the new system of species identification and discovery in 2003. The method uses a very short genetic sequence from a standard part of the genome, and is similar to the way a supermarket scanner distinguishes products using the black stripes of the Universal Product Code.

The work at ANIC, in collaboration with the Atlas of Living Australia (ALA), is contributing to the International Barcode of Life (IBoL) project. The IBoL reference library currently contains records for more than 100,000 species and their aim is to have 500,000 species barcoded by 2015.

ANIC is the first national collection to integrate the new barcoding approach for a major group of insects.

The collection's Director, Dr John LaSalle, says DNA barcoding is like 'genetic fingerprinting'.

"What's different about this blitz is that we said let's take a real priority look at Australian moths and butterflies," says LaSalle.

Rapid decision making tool

For the DNA analysis, one leg is taken off each specimen and ground up. The researchers then extract the DNA to record each specimen's unique genetic code. The results, together with a photo and other details, are added to the ALA and ANIC databases.

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New Research Suggests Conservation Biologists are Setting Minimum Population Size Targets Too Low to Prevent Extinction

A new study by University of Adelaide and Macquarie University (Australia) scientists has shown that populations of endangered species are unlikely to persist in the face of global climate change and habitat loss unless they number around 5,000 mature individuals or more.

The findings have been published in a paper entitled 'Pragmatic population viability targets in a rapidly changing world' in the journal Biological Conservation.

A long-standing idea in species restoration programs is the '50/500' rule. This states that at least 50 adults are required to avoid the damaging effects of inbreeding, and 500 to avoid extinctions due to the inability to evolve to cope with environmental change.

For this study, researchers investigated existing data regarding the minimum population size requirements for species based on empirical and theoretical estimates made over the past few decades. This literature was found to indicate that thousands, rather than hundreds, of individuals are required for a population to have an acceptable probability of riding out environmental fluctuation and catastrophic events, and ensuring the continuation of evolutionary processes.

"Often, [conservation biologists] aim to maintain tens or hundreds of individuals, when thousands are actually needed," says lead author Dr. Lochran Traill, from the University of Adelaide's Environment Institute. “Our review found that populations smaller than about 5,000 had unacceptably high extinction rates. This suggests that many targets for conservation recovery are simply too small to do much good in the long run."
"Our research suggests that the 50/500 rule is at least an order of magnitude too small to effectively stave off extinction," says Dr. Traill. "This does not necessarily imply that populations smaller than 5,000 are doomed. But it does highlight the challenge that small populations face in adapting to a rapidly changing world."

Team member Professor Richard Frankham, from Macquarie University's Department of Biological Sciences, says: "Genetic diversity within populations allows them to evolve to cope with environmental change, and genetic loss equates to fragility in the face of such changes."

Conservation biologists worldwide are battling to prevent mass extinctions in the face of a growing human population and its associated impact on the planet.

“We shouldn't necessarily give up on critically endangered species numbering a few hundred of individuals in the wild," says Dr Traill. "Acceptance that more needs to be done if we are to stop 'managing for extinction' should force decision makers to be more explicit about what they are aiming for, and what they are willing to trade off, when allocating conservation funds."

Other researchers in the study are Associate Professor Corey Bradshaw and Professor Barry Brook, both from the University of Adelaide's Environment Institute. Information from the University of Adelaide and EurekAlert.

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