The double life of the Komodo Dragon

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The Komodo dragon ( Varanus komodoensus) comes from the islands of Indonesia and is the largest extant lizard. Although a regular in zoo's and the likely source for the folk tails of dragons, it was only recently that new light was placed on the Komodo dragon and their reproductive behaviours.




It has been discovered that Komodo dragons can reproduce via a process called parthenogenesis, this is where a female is able to produce offspring without fertilisation (Watts et al., 2006). What is even more incredible is that the female can switch from both sexual reproduction with a male and asexual reproduction via parthenogenesis.
When a female reproduces through parthenogenesis she can only produce homozygous ZZ or WW. The ZZ chromosomes turn into viable fertile males while the WW chromosomes fail to develop, leaving only male offspring (Watts et al., 2006).

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Although the Komodo dragons population numbers in the wild are low, their reproductive plasticity could be an advantage, where females are able to find a new niche environment and start new populations without needing males already present within the population.  It may also be advantageous if population sizes are low and mate choice is hard to come by (Watts et al., 2006).

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References:
Watts, P.C., Buley, K.R., Sanderson, S., Boardman, W., Ciofi, C. & Gibson, R. 2006, "Parthenogenesis in Komodo dragons", Nature, vol. 444, no. 7122, pp. 1021-1022.