Two Komodo dragon females reproduced through parthenogenesis

Dec 21, 2006 07:57 GMT  ·  By

Virgin motherhood is not such a rare issue in nature. In many insects - such as the plant lice - it can be generalized. But also in some vertebrates, and especially amongst some small lizards like rock lizards, whiptails and geckos.

But scientists were taken by surprise to find that the largest lizards in the world are capable of "virgin births" or "parthenogenesis". Two recent cases of female Komodo dragons producing offspring without male contact have been signaled. One of the females, Flora, a resident of Chester Zoo in the UK, produced 11 eggs earlier this year.

Three died off, providing the material needed for genetic tests. "Flora laid her eggs at the end of May and, given the incubation period of between seven and nine months, it is possible they could hatch around Christmas - which for a 'virgin birth' would finish the story off nicely", said Kevin Buley, a curator at Chester Zoo.

Flora has never been kept with a male Komodo dragon. Tests revealed the offspring are not clones of their mother, but their genetic make-up was derived just from her. The team concluded they were a result of asexual reproduction.

The other female, called Sungai, is from the London Zoo in the UK, and produced four offspring earlier this year - more than two years after her last contact with a male. Genetic tests proved that Sungai's babies, which are healthy, were the result of parthenogenesis. Sungai reproduced also sexually, producing another offspring after mating with a male called Raja. "Parthenogenesis has been described before in about 70 species of vertebrates, but it has always been regarded to be a very unusual, perhaps abnormal phenomenon." said Richard Gibson, curator at the Zoological Society of London.

"It has been shown in some snakes, fish, a monitor lizard and even a turkey," he said.

"But we have seen this in two separate, unrelated female Komodo dragons within a year, so this suggests maybe parthenogenesis is much more widespread and common than previously considered."

"Because these animals were in captivity for years without male access, they reproduced parthenogenetically."

"But the ability to reproduce parthenogenetically is obviously an ancestral capability."

This ability could have enhanced a female washed up alone on an island with no males to establish a population. "Because of the genetics of this process, her children would always be male" said Gibson.

Sungai proved that female dragons are able to switch between sexual and asexual reproduction. There are fewer than 4,000 Komodo dragons in the wild, and they are found on three islands in Lesser Sunda (Indonesia): Komodo, Flores and Rinca.

This species is the largest living lizard: Adult males can grow up to 3m (10ft) in length and weigh up to 90kg (200lb). Ancient dragons that lived in Australia till recently were three times larger. To ensure genetic diversity of dragons kept in captivity, zoos should perhaps keep males and females together to avoid parthenogenesis.

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