"Rivals probably disrupt the flies' sleep patterns, which has already been identified as a cause of early death in many other species, and is potentially harmful to humans."
London, May 19 - Pursuit of sex may be a killer, at least for the male fruit flies who compete with other males over their potential mates, a study revealed.
Male fruit flies forced to compete with other males become less attractive to females and die young, the study noted.
The flies are not using antlers to beat each other into submission, but instead are harassing each other to the point where exhaustion causes them to die young, said evolutionary biologist Anne Lizé of University of Liverpool in Britain.
In the test, male fruit flies of the species Drosophila subobscura were kept either alone or in groups.
The females of this species are monandrous - they only mate once in their lives, meaning that males have to get very lucky to mate at all.
As a result, males compete furiously for access to females.
Females strongly prefer the males that were kept alone, with females refusing to mate with three quarters of the males that previously had to battle with rivals, the experiment showed.
When we see stags fighting over mates, it is obvious what the potential costs to the males are, but in this case it is more subtle, Lizé noted.
Rivals probably disrupt the flies' sleep patterns, which has already been identified as a cause of early death in many other species, and is potentially harmful to humans.
The idea that competition has more subtle effects on a male could be extended to other species that humans are trying to breed or keep healthy, Lizé concluded.