Virgin births at London Zoo
Thursday 21 December 2006
Four Komodo dragons hatched at London Zoo earlier this year were the result of parthenogenesis, it emerges this week.
A clutch of dragon eggs laid by adult female Komodo dragon Sungaï in August 2005 immediately fascinated reptile keepers at London Zoo. Sungaï arrived at London on loan from Thoiry Zoo in France in early 2005 and the clutch of eggs was laid more than two years since she had last lived with Thoiry's male, Kimaan. Since Sungaï hadn't yet met London Zoo's male Raja it was first thought she may have stored Kimaan's sperm for more than two years. However, the Zoological Society of London's (ZSL) Curator of Herpetology, Richard Gibson, wasn't entirely convinced and resolved to investigate further.
Genetic fingerprinting techniques at Liverpool University have confirmed that the four dragons were actually the result of parthenogenesis - the development of an egg without fertilization by a sperm. Sungaï later mated with Raja and subsequently laid a second small clutch of eggs from which a single, 'normal', dragon hatched, demonstrating that Komodo dragons can switch between asexual and sexual reproduction depending on the availability of a mate. The fact that Komodo dragons can reproduce asexually, and switch 'at will' back to normal sexual reproduction was completely unknown.
ZSL’s Curator of Herpetology Richard Gibson said: "I am delighted that the mysterious parentage of our Komodo dragon babies has been solved and that we have discovered something new to science at the same time. Knowing that the world's largest lizard can reproduce like this suggests that many other reptiles may also do this more often than we thought and may lead to changes in the way we manage this and other species in breeding programmes. This discovery also raises important questions about the natural history of dragons in the wild and will therefore help to safeguard the future of the species."
A full report into the findings, written in collaboration with the University of Liverpool and Chester Zoo will appear in Nature on Thursday December 21st 2006.
Liverpool University carried out the genetic fingerprinting research. Chester Zoo provided further DNA material from incubating eggs which have also proved to be produced by parthenogenesis.
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Notes to editors
- Baby dragons live mostly in trees for first 2-4years to avoid being eaten by larger dragons.
- Eggs take up to nine months to hatch.
- Largest living lizard – can be up to 3m and weigh 100kg.
- Only lizard to hunt and kill prey larger than itself and larger than it can swallow whole.
- It is the top predator in its environment (other than man) which is unusual for a reptile.
- Komodo dragons prey on snakes and lizards (including smaller Komodo dragons) domestic animals such as chickens, ducks, cats and dogs, pigs, goats as well as deer and water buffalo. Has been known to attack and eat people.
- Komodo dragon saliva contains over 50 species of bacteria and is virulently toxic. Dragons kill large prey by rushing from ambush along game trails, biting at legs and tendons, maiming the animal and then trailing the injured animal until septicaemia sets in and kills it.
- Skin is scaly like other reptiles but each scale has a small point of bone, called an osteoderm, making it very tough, like armour plating.
- Threatened through habitat loss from competition with man for food, woodland clearance and fires as well as occasional poaching and persecution.
- Males demonstrate ritual combat during breeding season by standing on their hind legs and wrestling.
- Sungaï was hatched on 1st May 1995 in Yogyakarta Zoo in Indonesia, and transferred to Thoiry Zoo in France in August 1998. Sungaï arrived at London Zoo in May 2005. Sungaï sadly died earlier this year.
- Raja, the male Komodo dragon at London Zoo was hatched in October 1998 and arrived in London in July 2004.
Founded in 1826, the Zoological Society of London (ZSL) is an international scientific, conservation and educational charity: our key role is the conservation of animals and their habitats. ZSL runs London Zoo and Whipsnade Wild Animal Park, carries out scientific research in the Institute of Zoology and is actively involved in field conservation in other countries worldwide.
Zoological Society of London
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