Thursday, December 21, 2006

KomodoDragon to give Virgin birth!

Flora, a komodo dragon in an English zoo is due to give birth to eight babies around Christmas. The catch is that Flora has not been with a male dragon. That's right, a Christmas-time virgin birth. Something about that just sounds familiar.

This kind of thing has been known to happen in other lizard species, but nobody knew it was possible with dragons.

"Nobody in their wildest dreams expected this. But you have a female dragon on her own. She produces a clutch of eggs and those eggs turn out to be fertile. It is nature finding a way," Kevin Buley of Chester Zoo in England said in an interview.

He said the incubating eggs could hatch around Christmas.

The process by which this happens is called parthenogenesis. From Wikipedia:

Parthenogenesis is distinct from artificial animal cloning, a process where the new organism is identical to the cell donor. Parthenogenesis is truly a reproductive process which creates a new individual or individuals from the naturally varied genetic material contained in the eggs of the mother. A litter of animals resulting from parthenogenesis may contain all genetically unique siblings. Parthenogenic offspring of a parthenogen are, however, all genetically identical to each other and to the mother, as a parthenogen is homozygous.

What this means is that the genome is not passed down whole as in cloning; The cells begin meiosis normally by fusing and shuffling their chromosomes, but instead of dividing into two separate haploid egg cells, they stay together essentially fertilizing themselves. The Wikipedia article has even been updated to include Komodo dragons.

Recently, the Komodo dragon which normally reproduces sexually was found to also be able to reproduce asexually by parthenogenesis. [3] Because of the genetics of sex determination in Komodo Dragons uses the WZ system (where WZ is female, ZZ is male, WW is inviable) the offspring of this process will be ZZ (male) or WW (inviable), with no WZ females being born. A case has been documented of a Komodo Dragon switching back to sexual reproduction after a parthenogenetic event. [4]. It has been postulated that this gives an advantage to colonisation of islands, where a single female could theoretically have male offspring asexually, then switch to sexual reproduction to maintain higher level of genetic diversity than asexual reproduction alone can generate. [5] Parthenogenesis may also occur when males and females are both present, as the wild Komodo dragon population is approximately 75 per cent male.

One has to wonder what these lizards, born of a virgin, on Christmas will be like when they grow up.

1 comment:

The Science Pundit said...

Richard Dawkins also has a nice explanation called The Komodo Dragon's Tale (an addendum to his book The Ancenstor's Tale)