Researchers at The University of Western Australia have discovered that male genitalia evolve in the same way that birds use brightly coloured feathers and insects use song - to promote male reproductive success.
Winthrop Professor Leigh Simmons and Associate Professor Paco Garcia-Gonzalez, from UWA's Centre for Evolutionary Biology, used an experimental evolution approach on dung beetles to explore the evolution of male and female genitalia. Their study will be published today online in Nature Communications.
"We either enforced monogamy or allowed sexual selection to continue in replicated dung beetle populations," Professor Simmons said.
"After four years, or 21 beetle generations, we analysed the changes in genital structures produced by the presence or absence of sexual selection, while also studying the genetic make-up underlying these genital traits. The results were very revealing.
"Males from the sexually selected groups evolved a penis that was elongated compared to males in the monogamous groups, while females from the sexually selected groups demonstrated a greater focusing and internalisation of the genital pits in which males need to gain anchorage if they are to mate successfully."
The researchers also found, for the first time in any species, distinct genetic variation in female genital structure and broad genetic links between the sexes for genital shape.
"Our results provide the most complete data available for any species on the mechanisms and evolutionary responses to sexual selection that have long been argued to underlie the rapid and divergent evolution of male genitalia," Professor Simmons said.
Professor Simmons' work in the field of evolutionary biology has had a significant impact on the development of the discipline and has attracted graduate students and postdoctoral fellows from around the world.