Australasian Science: Australia's authority on science since 1938

Suicidal Sex Explained

By Magdeline Lum

Sex is suicidal for some marsupials, and termites communicate by headbaging.

The full text of this article can be purchased from Informit.

August in Australia marks the mating season for the antechinus, a mouse-like marsupial. Males go into a frenzy mating with as many females as they can, with some encounters lasting up to 14 hours. By the end of the mating season, the males are literally falling apart and dying.

This death toll occurs in 20% of all known species of insectivorous marsupials, including all 12 species of antechinus, three species of phascogale, and kalutas. Some populations of northern quolls and dibblers also lose their males after the breeding season.

Research conducted by Dr Diana Fisher of the University of Queensland has overturned previous explanations for this die-off. A popular explanation has been that the deaths were altruistic as they prevented competition with offspring for resources.

However, Fisher found that a combination of extreme stress, immune system collapse, infections and internal bleeding led to the death of males. These males have spent the majority of their lives as juveniles and reach sexual maturity at 11 months just before breeding season begins.

In the month before breeding, their testes are shut down so that all the sperm they have stored is all that the males have. There will be no more, so even if a male survived the breeding season it wouldl be infertile. This injects urgency into mating.

When the life history of 52 species...

The full text of this article can be purchased from Informit.