Washington, September 19 : Studying the mating and nesting practices of a common Australian frog, Monash University researchers have found that they partner up to eight males sequentially, the highest recorded of any vertebrate.
Research leader Phillip Byrne, from the university's School of Biological Sciences, has revealed that the new behaviour observed in the frog species Bibron's toadlet (Pseudophryne bibronii) had never been detected in any frog species to date.
"Our study revealed that females made the active decision to distribute their eggs between the nests of up to eight different males," he said.
He joined forces with Professor Scott Keogh from Australian National University to carry out the study in an area at Jervis Bay National Park on the New South Wales south coast.
The researchers worked overnight shifts from 6 pm to 6 am, seven days a week for over four months and kept track of almost 100 frogs.
Using DNA markers, they observed that females that distributed their available eggs between the nests of more males, as opposed to leaving them in one nest, had elevated offspring survival, presumably by insuring against nest failure.
"Traditionally it was thought that males, but not females, should benefit from promiscuous behaviour because males generally invest less in reproduction. This level of promiscuity is a new record among vertebrates and certainly supports the old adage of not putting all your eggs in the one basket," Dr Byrne said.
"Our study advances our understanding of female promiscuity by being the first to show that promiscuous females can safeguard against choosing fathers that provide poor homes for their offspring.
"It is becoming increasingly apparent that females in many animal species choose to mate with multiple partners as a safeguard against choosing a genetically inferior sire, but insurance against a father who provides a lousy home is a novel and potentially widespread explanation for the evolution of female promiscuity," Dr Byrne said.