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A zoo keeper holds one of the five newly hatched Komodo dragons at Chester Zoo. ((Dave Thompson/Associated Press))

A British zoo on Wednesday announced the virgin birth of five Komodo dragons, giving scientists new hope for the captive breeding of the endangered species.

In an evolutionary twist, the newborns' eight-year-old mother, Flora, shocked staff at the Chester Zoo in northern England when she became pregnant without ever having a male partner or even being exposed to the opposite sex.

"Flora is oblivious to the excitement she has caused but we are delighted to say she is now a mum and dad," said a delighted Kevin Buley, the zoo's curator of lower vertebrates and invertebrates.

"When the first of the babies hatched, we didn't know whether to make her a cup of tea or pass her the cigars."

The shells began cracking last week, after an eight-month gestation period, which culminated with the arrival Tuesday of the fifth black and yellow dragon. Two more eggs remained to be hatched.

The dragons are between 40 and 46centimetres long andweigh between 100 and 113 grams, said Buley, who leads the zoo's expert care team.

He said the reptiles are in good health and enjoying a diet of crickets and locusts.

Some reptiles reproduce asexually

Other reptile species reproduce asexually in a process known as parthenogenesis. But Flora's virginal conception, and that of another Komodo dragon in April at the London Zoo, are the first documented in a Komodo dragon.

The evolutionary breakthrough could have far-reaching consequences for endangered species.

Captive breeding could ensure the survival of the world's largest lizards.Fewer than 4,000 Komodos are left in the wild.

Scientists hope the discovery will pave the way to finding other species capable of self-fertilization.

While it was not unusual for female dragons to lay eggs without mating, scientists realized they were witnessing something important when they discovered Flora's eggs had been fertilized.

DNA paternity tests confirmed the lack of male input, although the brood are not exact clones of Flora.

Parthenogenesis had only been noted once before in a Komodo dragon. Genetic tests showed that Sungai, a resident of theLondon Zoo, was the sole parent to offspring in April.

The process has been seen in about 70 species, including snakes and lizards.

Scientists are unsure whether female Komodo dragons have always had the ability to reproduce asexually or if this is a new evolutionary development.

The reptiles, renowned for their intelligence, have no natural predators — making them on par with sharks and lions at the pinnacle of the animal kingdom.

The Chester Zoo's latest star attractions will eventually be moved into a specially built enclosure so the public can gaze at the evolutionary miracles.