Thursday, December 21, 2006

 

Komodo Dragon Virgin Birth Expected at Christmas

The story of the Virgin Mary is what gives meaning to Christmas.

And now, Chester Zoo has a nativity story of its own - and a dragon's tale that promises to turn the traditional concepts of the birds and the bees on its head.

In a ground-breaking paper to be published in the scientific journal Nature next week, Chester Zoo has helped to prove that Komodo Dragons - the world's largest lizard - can reproduce in the absence of a male, parthenogenetically.

The key to this discovery lies with Flora - one of the zoo's two female Komodo Dragons - and began when Flora laid a clutch of 11 eggs in May this year.

The zoo's reptile keepers placed the eggs in an incubator. Three of the eggs collapsed but, once opened, were found to contain embryos - showing that they were fertile.

Fertile dragon's eggs are not in themselves unusual, but what made this news surprising was that virgin Flora has never been mixed with, or mated by, a male dragon. Scientists at Liverpool University under the guidance of Dr Phill Watts, carried out genetic fingerprinting on the three eggs and on the adult Komodo Dragons at the zoo. This 'paternity' testing proved that Flora was indeed both the ‘mother' and the ‘father' of the fertile eggs.

Kevin Buley, Chester Zoo's Curator of Lower Vertebrates and Invertebrates and a co-author of the Nature paper, said: "Although other lizard species are known to be able to reproduce by parthenogenesis, this is the first time this has ever been reported in Komodo Dragons."

"Essentially what we have here is an imminent virgin birth and, because the eggs were laid back in May, it is not beyond the realms of possibility that the incubating eggs could hatch around Christmas time. We will be on the look out for shepherds, wise men and an unusually bright star in the sky over Chester Zoo."

The Nature paper demonstrates that, whilst the fertile eggs are not identical clones of Flora, the overall genetic make-up of the clutch reconstructs the genetic make-up of the mother exactly, and that no other Komodo Dragon could have been involved in the production of the embryos.

"This discovery has very important implications for understanding how reptiles are potentially able to colonise new areas. Theoretically a female Komodo Dragon in the wild could swim to a new island and then establish an entirely new population of dragons. The genetics of parthenogenesis in lizards means that all her hatchlings would have to be male. These would grow up to mate with their own mother and therefore, within one generation, there would potentially be a population able to reproduce normally on the new island," added Kevin. [Source: Chester Zoo]

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Based on the journal Nature paper:

"Parthenogenesis in Komodo dragons"

Phillip C. Watts, Kevin R. Buley, Stephanie Sanderson, Wayne Boardman, Claudio Ciofi and Richard Gibson

doi:10.1038/4441021a

Abstract

Parthenogenesis, the production of offspring without fertilization by a male, is rare in vertebrate species, which usually reproduce after fusion of male and female gametes. Here we use genetic fingerprinting to identify parthenogenetic offspring produced by two female Komodo dragons (Varanus komodoensis) that had been kept at separate institutions and isolated from males; one of these females subsequently produced additional offspring sexually. This reproductive plasticity indicates that female Komodo dragons may switch between asexual and sexual reproduction, depending on the availability of a mate - a finding that has implications for the breeding of this threatened species in captivity. Most zoos keep only females, with males being moved between zoos for mating, but perhaps they should be kept together to avoid triggering parthenogenesis and thereby decreasing genetic diversity.

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*Info on Komodo Dragons:

The Komodo dragon or Komodo Monitor (Varanus komodoensis) is the largest living lizard in the world, growing to an average length of 2-3 meters (approximately 6.5-10 feet). It is a member of the monitor lizard family, Varanidae, and inhabits various islands in Indonesia.

Sightings of the Komodo dragon were first reported to Europeans in 1910. Widespread knowledge came after 1912, in which Peter Ouwens, the director of the Zoological Museum at Bogor, Java, published a paper on the topic. In 1980, the Komodo National Park was founded to help protect their population. (More)

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**A related news report from April 26th, 2006:

"Komodo Dragon Births Leaves Experts Foxed"

Zoologists on Monday said they were delighted and perplexed at the birth of four rare Komodo dragons, whose paternity remains a mystery. The four reptiles were born last month from a clutch laid at London Zoo by a female called Sungai.

Sungai normally lives at the Thoiry wildlife park, west of Paris, but was lent to London as part of a European breeding programme to help this badly-endangered species.

But Sungai laid the fertilised eggs before even meeting her British lover - and the last time she is known to have had intercourse was two years ago, with another Thoiry Komodo dragon called Kinaam.

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***Info on Parthenogenesis:

Parthenogenesis or virgin birth (from the Greek parthenos, "virgin", genesis, "birth") describes the growth and development of an embryo or seed without fertilization by a male. Parthenogenesis occurs naturally in some species, including lower plants (called agamospermy), invertebrates (e.g. water fleas, aphids, some bees and parasitic wasps), and vertebrates (e.g. some reptiles, fish, and, very rarely, birds). (More)

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