Virgin Birth (to a Komodo Dragon)

At a zoo in England, a Komodo dragon has laid eggs that have hatched even though she has never been exposed to a male:

Scientists unveiled five squirmy black and yellow Komodo dragons Wednesday that were the product of a virgin birth, predicting that the hatchlings offered hope for breeding the endangered species.

Flora, the Komodo dragon, has produced five hatchlings although a male has never been close to her, the proud staff at the 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," said a delighted Kevin Buley, the zoo's curator of lower vertebrates and invertebrates.

...

That ravenous appetite explains why Flora isn't allowed anywhere near her offspring.

"No maternal instincts exist in Komodos so it is perfectly natural to keep them as far apart as possible," Buley said. "She would try to eat anything that comes in front of her."

About 70 reptile species including snakes and lizards are known to reproduce asexually in a process known as parthenogenesis. But Flora's virginal conception, and that of another Komodo dragon in April at the London Zoo, are the first documented in Komodo dragons.

Do you think the Virgin Mary was the only recorded example of this in humans? If they had a really sick sense of humor, they would name one of the offspring Jesus.

Actually, parthenogenesis -- asexual reproduction -- is relatively common in reptile species. The speculation that I have heard as to why is that under circumstances when population density is low, it is easier for the female to reproduce without a mate. This brings up an interesting problem with species like Komodo dragons that are endangered. If we keep the females separated from the males, they may begin to think that the population density is too low and start laying eggs by parthenogenesis. On the one hand, this may be good because it is endangered, and at the end you will have more of them. On the other, there is a lower genetic diversity in the offspring because of the asexual reproduction -- you want to maintain genetic diversity to prevent the species from becoming inbred.

The resulting babies are not clones of the mother; they are not perfectly identical. They are all male because of a complexity in reptiles where they female has mixed sex chromosomes and the male has the same two. In humans, women have two X chromosomes, and men have an X and a Y. In Komodo dragons, it is reversed. (They use what is called the WZ system of sex determination.) The females have a W and a Z, and males have a two Z chromosomes. Parthenogenesis is a process whereby the chromosomes from a single egg become duplicated, and the animal becomes viable. In Komodo dragons, WW is inviable, leaving the only viable combination that can result from this process to be a male (ZZ).

Wikipedia has a good article on the process of parthenogenesis.

The article in Nature where they discuss this example for Komodo dragons is here (the site appears to be down at the moment, but it should be back eventually).