Wednesday, 12 February 2014

What Female Dragons can do.


The females of Komodo dragons can give birth to baby lizards without previous contact with males. This kind of asexual reproduction is called parthenogenesis and has been observed in females kept in captivity without any relations with opposite sex individuals for years, if not for all their life.

Komodo dragons are huge monitor lizards – up to 3 meters length- who live only in a few islands of central Indonesia. Most probably parthenogenesis could be for them the only solution to continue the species under extreme condition of isolation. In nature that can happen due to a storm which can lead astray a single varanus while swimming from island to island. Strong marine currents present in the area, could also carry the dragon far away from its group to an unpopulated territory.

The reproduction without fertilization of the egg can give birth only to male individuals because of genetic combinations. Females have chromosome ZW and all the eggs carry one chromosome, W or Z. Their union will give the male combination ZZ or WW. Eggs with the latter sequence are not going to hatch. Certainly, this way of procreating is not very healthy for the species being the genetic make-up derived only from one parent, but the offspring will grow normally and will be able to mate.

Parthenogenesis is very rare in vertebrates, but has been observed in snakes, fishes and even turkeys. Nevertheless, its discovery among Komodo dragons has been the reason to reconsider it as “not so exceptional”.