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  ABC.net 22 Nov 06
Turtles give up their DNA for science

Scientists have conducted the first genetic census of endangered green turtles throughout southeast Asia and Australia, providing a conservation tool.

"The green turtle is on the red list of endangered species internationally, so we wanted to be able to identify if there were particular groups that might need specific conservation efforts," says PhD student Kiki Dethmers from the University of Queensland.

Her work on the turtle Chelonia mydas appears in the November issue of the journal Molecular Ecology.

Turtle populations are shrinking for a range of reasons, she says. Some are hunted for food, others are accidentally caught in fishing nets, while others still are affected by a loss of habitat or viral diseases.

Dethmers and her colleagues gathered skin or blood samples from turtles nesting at 27 different sites in Malaysia, the Philippines, Micronesia, Indonesia, Papua New Guinea and Australia. From each sample they extracted a mitochondrial DNA, genetic material that is passed down from mother to child.

"Mitochondrial DNA is inherited through the female line, and females come to the beaches to nest, so our study was based on sampling the female population," Dethmers says.

The results show that there are just 17 distinct genetic groups within the region. Some groups were made up of a single nesting beach.

But in other cases, nesting sites in different locations turn out to be genetically related.

Some of the groups were substantial, such as the 125,000 related turtles that nest on Western Australia's northwest shelf.

Others, like some groups in Malaysia, might contain just a few hundred turtles.

The information Dethmers and her colleagues have gathered could be vital for future conservation efforts.

"The turtles' situation varies from one area to another," she says. "Our data would be useful for example if one of the groups is particularly threatened, because it would give you an idea of how many turtles are being affected.

"This can help you make predictions about whether that is going to make a certain population go extinct."
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