Thursday, January 25, 2007

 

Komodo Dragons: News, Video, Further Reading

Contents:

1) News from Chester Zoo and related Nature paper
2) "The Dragons of Komodo" (Video from Indonesia Network)
3) Further Reading
4) Recent Posts

1) News from Chester Zoo and related Nature paper

January 2007: Enter the dragons - meet the latest Chester Zoo additions, the long-awaited Komodo Dragon babies born to virgin mum, Flora.

Flora, one of the zoo's two female Komodo dragons - the world's largest lizard - became an overnight Christmas star when it was revealed in a groundbreaking article in the world's leading science journal Nature (see below), that she had laid a clutch of fertile eggs without ever being mixed with, or being mated by, a male dragon.

After an anxious wait, Chester Zoo's keeping staff are celebrating the hatching of five baby dragons. Two fertile eggs still remain in an incubator.

The arrival of the five babies - which measure 40-45 centimetres in length and weigh 100-125grams each (larger than many full grown adult lizards) - brings a happy end to Flora's story which began last year.

When Flora laid her eggs back on 21st May, they were put in an incubator where three of them collapsed after only a couple of weeks. When they were opened however, staff were astounded to find that they contained embryos - showing that they were fertile.

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, the zoo's Curator of Lower Vertebrates and Invertebrates, said: "Flora is oblivious to the excitement she has caused but we are delighted to say she is now a mum and dad. 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 five new additions are currently being cared for in the zoo's specialist off-show area where they are enjoying a diet of crickets and locusts and receiving specialist care in their early days. The dragons will eventually be moved into a purpose-built baby dragon enclosure on public display.

Currently black and yellow, the new dragons - all male - will eventually lose their bright colouring as they grow.

"Even though they are only a few days old, our baby dragons are doing very well and receiving the expert care they need at this time. We haven’t made a decision on names yet - as Komodo dragons can live for over 40 years, we want to get the names just right," added Kevin.

The incubation period for Komodo eggs is between 7 and 9 months. Flora and sister Nessie are part of a European zoo breeding programme to help protect this threatened species, and can be seen in the zoo's Islands in Danger exhibit which was opened by Deputy Prime Minister John Prescott.

Further Information:

• Five of Flora’s seven eggs have so far hatched. The first baby started to emerge on the 15th January. Other eggs hatched on the 17th, 18th, 21st and 22nd. Zoo staff are keeping their fingers crossed for the two remaining eggs, which could hatch any day.

• The study published in Nature was written in conjunction with London Zoo and the University of Liverpool.

London Zoo provided further DNA material from hatchling dragons which have also been proved to have been produced parthenogenetically.

• Komodo Dragons are the largest lizards in the world, with adult males growing up to 3 metres in length and weighing up to 90Kg.

• There are now believed to be less than 4000 Komodo Dragons left on the planet. They survive on only 3 islands in Indonesia - Komodo, Flores and Rinca - and are still under threat in certain areas of their range as a result of habitat loss and the disappearance of their mammal prey.

• Komodo Dragons are known to be excellent swimmers and can swim across the sea from one island to another.

• Although they are not considered to be poisonous, the saliva from a Komodo Dragon contains a host of deadly bacteria. Wild dragons will ambush and bite their prey and will then track it for up to 2 days until it eventually dies from blood poisoning.

• The first human inhabitants of Komodo were the Ata Modo. They believed that they were created at the same time as the Komodo Dragon when a beautiful spirit woman Putri Naga gave birth to twins - one of the babies was a human child, the second a Komodo Dragon. [Source: Chester Zoo]

Related Nature paper:

Parthenogenesis in Komodo dragons

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

Nature 444, 1021-1022 (21 December 2006) | doi:10.1038/4441021a

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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2) "The Dragons of Komodo" (Video from Indonesia Network)

3) Further Reading:

3a) Excerpts from the evolution section of The Biogeography of the Komodo Dragon:

...They share a common past with dinosaurs but are not direct descendants. Both dinosaurs and monitor lizards belong to the subclass Diapsida (Ciofi, 1999).

...Fossil evidence supports the idea that Komodo dragons may be relics of a larger distribution, stretching as far as the eastern portion of Flores to Timor. Fossils from pygmy elephants, stegodont, found on both Timor and Flores suggest that the two islands may have been close enough to allow migration during the Pleistocene era.

3b) In March 1999 the journal Scientific American published an article by Claudio Ciofi titled:

"The Komodo Dragon: On a few small islands in the Indonesian archipelago, the world's largest lizard reigns supreme":

...Wolfgang Bohme of the museum of natural history in Bonn has contributed much to our understanding of the rise and evolution of the Varanus genus, based on morphological data. Dennis King of the Western Australian Museum and Peter Baverstock and his colleagues at Southern Cross University are continuing research into the evolutionary history of the genus through comparisons of DNA sequences and chromosomal structure of varanid species and related families. They have concluded that the genus originated between 40 and 25 million years ago in Asia...

...The limited resources of an island could have driven the evolution of the pygmy elephants, because smaller individuals, with lower food requirements, would have been selected for. In contrast, today's Komodo dragon may have evolved from a less bulky ancestor; the availability of the relatively small elephants as prey may have been a driving force in the selection of largeness that resulted in the modern threemeter Komodo...

...Further attempts to reconstruct the Komodo's evolutionary history require more comprehensive fossil finds and accurate dating of the islands that harbor extant populations. The work of King and Baverstock, as well as the integration of paleogeographic data and genome analysis, should shed more light on the origin of the species...

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4) Recent Posts:

"Komodo Dragon Virgin Birth Expected at Christmas"

"Bad News For Tolkien Fans - Flores 'Hobbit' Is Just A Miniman"

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