A fascinating new study from the forthcoming issue of The American Naturalist attempts to explain the mysterious persistence of two forms of females in many diving beetle populations. Their findings have important implications for theories of sexual conflict, which arises when the costs and benefits of multiple matings differ for males and females.
“The male versus female arms race (involving physical structures, behaviors, chemicals, etc.) for control over mating may take place over evolutionary time, which in theory can lead to the formation of a new species,” explain the authors.
Examining species of diving beetles that have two forms of females – for example, one with a smooth back and another furrowed – the researchers found that this polymorphism is actually a stable state, that is, neither of the forms go extinct.
“The results have implications for the understanding of how genetic diversity is maintained in populations where sexual conflict characterizes the mating system,” write the authors. “It also affects our theoretical expectations of sexual conflict as a species creator.”