Killed By Housework: Exhausting Pregnancy Means Female Komodo Dragons Live Half as Long as Males

Another post from Animalia, this time on the hardships of being a female komodo dragon.

Varanus komodoensis by Dezidor (Wikimedia Commons)

A study in the open-access journal PLoS ONE has shown that female dragons live to just half the age of their male counterparts because of the exhausting ‘housework’ they have to do during and after pregnancy.

A team of scientists from Australia, Italy and Indonesia (the natural home of the komodo dragon, Varanus komodoensis) studied 400 individuals for 8 years, from 2002 to 2010, to look at the difference in growth patterns and life expectancy between males and females. While males live to around 60 years, the female average is just 32 years, and this is thought to be because of the huge energy investment of females in reproduction. During the process of producing eggs and then building and guarding nests, females seem basically to fast for a period of up to 6 months, consequently losing body mass and fitness.

Male and female growth is in fact the same until they reach sexual maturity at 7 years old, and then females grow slower and less than males, and then die much younger. The difference between male and female size may also be linked to competition between males. Since the females die so young, there are more males than females overall, leading to high competition for females. In this case, then, larger size is a huge advantage because it makes the male both more attractive to females, and more able to fight off other males.

It is hoped that this research can help in the conservation of this legendary animal, listed as vulnerable by the IUCN. One of the problems at the moment seems to be a lack of egg-laying females. Because of the huge energy females invest in reproduction, they need to be extremely healthy before their fasting period, which might be a problem with increasing habitat destruction. Although they have sadly become locally extinct on part of the Indonesian island of Flores, this has encouraged more work to protect them elsewhere.