The Komodo Dragon

Komodo Dragon. Photo by Mark Dumont

There are so many myths about dragons.  They do not fly or rise menacingly from the depths of the sea.  No they live on an island in Indonesia.

St George never even saw one and if he had, my money would have been on the dragon anyway. For a start they have a strong bite and a mild but painful venom.  A modern myth was that their saliva was rife with bacteria which would cause their prey to drop from septic wounds a few days following an attack.  But contrary to this popular belief, recent findings show that the dragon’s saliva has no more bacteria than that of any meat eater that doesn’t brush its teeth twice daily.

One myth that does turn out to be true though, is the one about virgin birth.  Several Komodo dragons in zoos have given birth without the need of mating.  This method of asexual reproduction is known as parthenogenesis.

In the natural world there are many different systems for determining the sex of offspring.  These include having different numbers or types of chromosomes, or the temperature of the egg.  In humans, males are the heterogametic sex meaning that they have two different sex chromosomes one called X and the other called Y.  Females are homogametic meaning they have two X chromosomes.  For birds and many reptiles including the biggest lizard, the Komodo dragon, the female is the heterogametic sex and has two different sex chromosomes, one called Z and the other called W.  In this case it is the male that is the homogametic sex having a pair of Z chromosomes.

Sometimes the unfertilised eggs of Komodo dragons can double the number of their chromosomes meaning that a mama dragon can have male children made entirely from her own genetic material.

Some have suggested that this reproductive adaptation allows a single female to enter an isolated ecological niche (such as an island) and by parthenogenesis produce male offspring, establishing a sexually reproducing population.

Lets not get started on the Oedipus myth…..

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