Researchers at The University of Western Australia have found that not only do some female dung beetles have bigger horns than males but also use their horns as weapons in competition with other females for access to dung, which they then use in breeding.
The research by postgraduate student Nicola Watson and Professor Leigh Simmons, Director of UWA's Centre for Evolutionary Biology, is published today in the prestigious international biological research journal Proceedings of the Royal Society B.
The Royal Society is the world's oldest scientific academy in continuous existence, and has been at the forefront of enquiry and discovery since its foundation in 1660.
Ms Watson said traits such as antlers or horns that function as weapons or to attract mates typically occurred in male animals.
"However, there are some rare examples from nature of females possessing such structures," she said. "Our study found that in a certain species of dung beetle, in which females have much larger horns than males, females use their horns as weapons in competition with other females for access to dung, which they use for offspring production.
"Our findings indicate that even though females may not compete to attract males, female competition for breeding resources can favour the evolution of female weaponry."
Ms Watson's PhD thesis "Reproductive competition promotes the evolution of female weaponry" investigates the evolution of female ornamentation, using the dung beetle, Onthophagus sagittarius, as a model species.
Most researchers have focused on sexual selection in male animals and Ms Watson said it was time to redress the imbalance.
Nicola Watson (UWA School of Animal Biology) (+61 8) 6488 3425 / (+61 4) 20 542 034
Professor Leigh Simmons (Centre for Evolutionary Biology) (+61 8) 6488 2221
Sally-Ann Jones (UWA Public Affairs) (+61 8) 6488 7975 / (+61 4) 20 790 098