Sunday, December 24, 2006

Virgin Komodo prepares to give birth

Chester, England: In an evolutionary twist, Flora, a Komodo dragon from a UK zoo has managed to become pregnant without any male help.

Other reptile species reproduce asexually in a process known as parthenogenesis. But Flora’s virginal conception and that of another Komodo dragon earlier this year at the London Zoo, are the first time it has been documented in a Komodo dragon.

Native to Indonesia, Komodos are the world’s largest predatory lizards.

The cases of Flora and the London lizard, Sungai, are described in a study published Thursday in Nature.

Parthenogenesis is a process in which eggs become embryos without male fertilisation. It has been seen in about 70 species, including snakes and lizards. Scientists are unsure whether female Komodo dragons have always had this latent ability to reproduce or if this is a new evolutionary development.

Having been raised in captivity, Flora has never been exposed to a male Komodo dragon.

Her keepers first became suspicious in May, when she laid 25 eggs.

Though it’s not uncommon for female dragons to lay eggs without mating, such eggs are not usually fertilised. When three of them collapsed, scientists took a closer look.

“We saw blood vessels and a small embryo,” said Kevin Buley, a reptile expert at Flora’s home at the Chester Zoo in the northern England town. “And we knew immediately that Flora had fertilised the eggs herself.”

They sent the collapsed eggs, along with tissue samples from Flora, Nessie, and a male Komodo dragon, to a laboratory that conducted genetic testing to determine the eggs’ parentage. Results showed that their DNA could not have come from any other dragon.

At the London Zoo, Sungai gave birth to four dragon hatchlings in April through self-fertilisation. After their births, Sungai went on to mate normally with a male dragon, producing another baby dragon.

In contrast, other lizard species that reproduce asexually cannot mate normally.

That might give Komodos a distinct survival edge. Experts are keen to find out how prevalent Komodo virgin births are in the wild.

“It’s baffling why a species starts doing this,” said Dr Kevin de Queiroz, a research zoologist at the Smithsonian Museum of Natural History in Washington. “It would be helpful to know how often this happens and what the mechanism is that allows them do that.’’


Thanks to Dr.Sangeeta Dhanuka


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