Komodo Parthenogenesis

[Cynical Cat]

The Beeb

Virgin births' for giant lizards

A parthenogenic Komodo dragon hatching from its egg (Ian Stephen)
There have been two reported cases of Komodo dragon "virgin births"

Komodo dragons
The largest lizards in the world are capable of "virgin births".

Scientists report of two cases where female Komodo dragons have produced offspring without male contact.

Tests revealed their eggs had developed without being fertilised by sperm - a process called parthenogenesis, the team wrote in the journal Nature.

One of the reptiles, Flora, a resident of Chester Zoo in the UK, is awaiting her clutch of eight eggs to hatch, with a due-date estimated around Christmas.

Kevin Buley, a curator at Chester Zoo and a co-author on the paper, said: "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.

"We will be on the look-out for shepherds, wise men and an unusually bright star in the sky over Chester Zoo."

Flora, who has never been kept with a male Komodo dragon, produced 11 eggs earlier this year. Three died off, providing the material needed for genetic tests.

These revealed the offspring were not exact genetic copies (clones) of their mother, but their genetic make-up was derived just from her.

The team concluded they were a result of asexual reproduction, and are waiting for the remaining eight eggs to hatch.

Abnormal phenomenon?

Another captive-bred female called Sungai, at London Zoo in the UK, produced four offspring earlier this year - more than two years after her last contact with a male, the scientists reported in the same paper.

Again, genetic tests revealed the Komodo dragon babies, which are healthy and growing normally, were produced through parthenogenesis.

Sungai was also able to reproduce sexually, producing another baby offspring after mating with a male called Raja.


Maybe parthenogenesis is much more widespread and common than previously considered
Richard Gibson

Richard Gibson, an author on the paper and a curator at the Zoological Society of London, said: "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."

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."

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

Komodo dragon born to Sungai (Daniel Sprawson/ZSL)
Sungai's offspring are doing well

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

He said the lizards could make use of the ability to reproduce asexually when, for example, a lone female was washed up alone on an island with no males to breed with.

Because of the genetics of this process, he added, her children would always be male.

This is because Komodo dragons have W and Z chromosomes - females have one W and one Z, males have two Zs.

The egg from the female carries one chromosome, either a W or Z, and when parthenogenesis takes place, either the W or Z is duplicated.

This leads to eggs which are WW and ZZ. WW eggs are not viable, but ZZ eggs are, and lead to male baby Komodo dragons.

And like Sungai, she would be able to switch back to sexual reproduction, so she could breed to establish a new colony.

There are fewer than 4,000 Komodo dragons in the wild, and they are found in three islands in Indonesia: Komodo, Flores and Rinca.

Adult males can grow up to 3m (10ft) in length and weigh up to 90kg (200lb) - making them the biggest lizards on the planet.

The researchers said that, to ensure genetic diversity of Komodo dragons kept in captivity, zoos should perhaps keep males and females together to avoid asexual reproduction.

[Comrade Tortoise]

Hmm... Nice. Not particularly surprising considering how common pathenogenesis is, but nice.

It would be nice to have an actual virgin birth around christmas. hehe

[SirNitram]

I, for one, welcome our new, draconic savior.

[Shark Bait]

Damn it why can everyone asexually reproduce except me, maybe i'm just not trying hard enough.


DEVIDE DEVIDE!!!

[LadyTevar]

Damn it why can everyone asexually reproduce except me, maybe i'm just not trying hard enough.


DEVIDE DEVIDE!!!

Helps if you can spell it... DIVIDE

[Scottish Ninja]

Don't worry, I'm having problems getting it to work too.

And that's not even taking into consideration the sexual reproduction too.

[Comrade Tortoise]

Damn it why can everyone asexually reproduce except me, maybe i'm just not trying hard enough.


DEVIDE DEVIDE!!!

Helps if you can spell it... DIVIDE

He never had been able to spell well...

[Shark Bait]

Damn it why can everyone asexually reproduce except me, maybe i'm just not trying hard enough.


DEVIDE DEVIDE!!!

Helps if you can spell it... DIVIDE

He never had been able to spell well...

Nope! My first grade teacher thought I was retarded cause I couldn’t grasp spelling in the least, and the vast majority of the time I post anything here I type it in word first.

[Mayabird]

A neat little adaptation there: Make Your Own Breeding Population. You don't have to be so lucky as to get a mating pair on the same island or a gravid female just so happening to land on the island to establish a population.

[LadyTevar]

Question: Have they hatched yet?

[Mayabird]

Question: Have they hatched yet?

They just did.

Virgin lizard becomes new parent

Five of the seven Komodo dragon eggs have hatched so far

A female Komodo dragon which laid fertilised eggs despite being a virgin is now a mother and "father" of five.

Flora produced a clutch of 10 eggs without mating at Chester Zoo, Cheshire, in May 2006.

Although other lizards reproduce this way, it has only recently been recognised in Komodo dragons.

The five male hatchlings are up to 18 inches (46cm) long and weigh about 4ozs (113g). Two eggs are still in incubation and three others collapsed.

The newborn lizards feed on locusts and crickets and can be seen at the zoo from Easter.

The hatchlings are black and yellow, but the bright colours will fade with time.

Genetic fingerprinting

Kevin Buley, curator of lower vertebrates and invertebrates at Chester Zoo, 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 hatchlings, who will be moved to an enclosure on public display at the zoo around Easter, will grow to three metres in length - the Komodo dragon is the world's largest lizard.

Mr Buley said the young reptiles had not been named yet.

"As Komodo dragons can live for over 40 years, we want to get the names just right," he said.

Threatened species

When Flora, one of the zoo's two female Komodo dragons, laid her eggs in May, they were put in an incubator where three collapsed.

On opening them, staff discovered they contained embryos, and genetic fingerprinting by scientists at Liverpool University showed Flora's eggs had developed without being fertilised by sperm - a process called parthenogenesis.

All Komodo dragons bred in this way will be male.

The new clutch are the first Komodo dragons to born at Chester Zoo, where Flora and sister Nessie are part of a European zoo breeding programme to protect the threatened species.

It is believed there are fewer than 4,000 Komodo dragons left in the world, and those living in the wild live on three islands in Indonesia, which they swim between.

While not poisonous, their saliva contains a host of deadly bacteria.

In the wild they ambush and bite their prey and then track it for up to two days until it dies of blood poisoning.

http://news.bbc.co.uk/2/hi/uk_news/engl ... 293831.stm

[Comrade Tortoise]

Ah, glorious parthenogenesis. Such a wonderful adaptive strategy for colonization of isolated habitats. Only problem is that it leads to a lack of genetic diversity in a population started in such a manner. It eventually needs a diversity injection.

[LadyTevar]

Question: Were all the babies female? Or do the Komodo have the same adaptation that crocs and alligators do, where temperature decides the sex?

[Mayabird]

Question: Were all the babies female? Or do the Komodo have the same adaptation that crocs and alligators do, where temperature decides the sex?

The five male hatchlings are up to 18 inches (46cm) long and weigh about 4ozs (113g).
...
All Komodo dragons bred in this way will be male.

Komodo dragons have ZW sex chromosome system. Females are ZW and males are ZZ. When these females do their parthenogenesis trick, they produce WW and ZZ embryoes. The WW ones are nonviable but the ZZs (male) can hatch. Thus, in a pinch, if she's still stuck on the island with no males, she can mate with her offspring and they can start a population there.

As CT pointed out, it's not too good for genetic diversity, but if other dragons wash up on the island, say, thirty years later, they'll find a population already there to mate with, including both males and females.