Dragon Tale: Female Komodo Sacrifice Life for Housework

Demanding family matters and work are known to reduce by half the lifespan of female komodo.  The world's largest lizards are known for their long, flat heads with rounded snouts, scaly skin, bowed legs, and huge, muscular tails. They have thrived in the harsh climate of Indonesia's Lesser Sunda Islands for millions of years. Their formidable body size enables them to serve as top predators killing water buffalo, deer and wild boar and they have also been known to kill humans.

A recent study on this endangered lizard states that female Komodo Dragons lives only half the lifespan of males, on an average.

The research team that included scientists from the University of Melbourne, Australia, Indonesia and Italy predict that this huge difference could be due to their physically demanding 'housework' such as building huge nests and guarding eggs for up to six months.

For the study the team studied 400 individuals Komodo Dragons for 10 years in eastern Indonesia, their only native habitat. During this period they produced a model of the Dragon's growth rate.

According to the analysis, males live around 60 years of age, reaching an average of 160 cm in snout-vent length and 65 kg at adulthood. Whereas their female counterparts were estimated to live an average of 32 years and reach only 120 cm in snout-vent and 22 kg weight.

Dr Tim Jessop from the Department of Zoology at the University of Melbourne was a co-author on the study and said that, "the team were surprised by the significantly shorter lifespan of the female Komodo Dragon."

"The sex-based difference in size appears to be linked to the enormous amounts of energy females invest in producing eggs, building and guarding their nests. The process can take up to six months during which they essentially fast, losing a lot of weight and body condition, he said.

"Males and females start off at the same size until they reach sexual maturity at around seven years of age. From then on females grow slower, shorter and die younger."

Apart from this the team was keen to recognize the growth rate of komodo Dragons as this critical process can signify how the species prioritises its energy use in lifestyle and reproductive strategies.

According to the study females have high energy 'costs' for reproduction resulting in their smaller size, whereas to reproduce successfully, males must keep increasing in size.

The results provide important information on the endangered lizards' growth rate, lifestyle and population differences, which may help plan conservation efforts.

The study has consequences for the endangered species as early female deaths may be exacerbating competition between males over the remaining females, possibly explaining why males are the world's largest lizards.

"These results may seem odd to humans when the life span between Australian men and women differ by five years. But each species has different strategies to pass on their genes. For example humans invest a lot of energy in few children as raising them is very energy intensive, whereas insects will have hundreds of offspring with no input into their rearing."

The study results were published in the current issue of international journal PLoS ONE.