A fruit fly. Cambridge University scientists found genes with the ability to be switched on and off in female flies, which allow them to reproduce independently - with no need for a male. PHOTO BY JOSE CASAL/SWNS
The secret to virgin births has been discovered – in the humble fruit fly.
Cambridge University scientists found genes with the ability to be switched on and off in female flies, which allow them to reproduce independently – with no need for a male.
For the first time, scientists successfully induced virginal births in an animal that normally reproduces sexually by altering genes in the flies.
The virgin offspring – always female – were also found to retain this genetic ability once born.
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The ground-breaking study is also hoped to inform further research into the ability of crop pests to give virgin births.
The study, which was completed over six years and involved more than 220,000 virgin fruit flies, was published in the journal Current Biology.
Most animals have no other option than to reproduce sexually, with a female’s egg becoming fertilized by a male’s sperm.
Virgin births, or “parthenogenesis,” is the process by which an egg develops into an embryo without being fertilized by sperm – rendering a male partner unnecessary.
Dr. Alexis Sperling. The ground-breaking study is also hoped to inform further research into the ability of crop pests to give virgin births. PHOTO BY UNIVERSITY OF CAMBRIDGE/SWNS
Though the offspring of virgin births are not exactly clones of their mothers, they were found to be very similar genetically and always female.
The research team first studied the genetic makeup of two strains of another species of fly, called Drosophila mercatorum.
One of the two strains requires males to reproduce, whereas the other reproduces only through virgin births.
Scientists identified which genes were switched on or off in the strain able to reproduce without fathers.
The researchers then alternated what they presumed were the corresponding genes in the model fruit fly – Drosophila melanogaster.
The experiment was a success: the fly miraculously acquired the ability for virgin birth.
Study lead author Dr. Alexis Sperling, a researcher at the University of Cambridge, said the discovery of how to engineer virgin births was highly exciting.
He explained: “In our genetically manipulated flies, the females waited to find a male for half their lives – about 40 days – but then gave up and proceeded to have a virgin birth.
“We’re the first to show that you can engineer virgin births to happen in an animal.
“It was very exciting to see a virgin fly produce an embryo able to develop to adulthood, and then repeat the process.”
Once the ability to give virgin births was induced in fruit flies, the researchers also found that this was passed on through generations, meaning offspring could either reproduce sexually with a male or, if there aren’t any around, give birth independently.
However, just 1-2 percent of the second generation of female flies with virgin birth abilities actually produced offspring, and this only occurred when no male flies were present.
When males were available, the females simply mated and reproduced in the normal way.
But switching to a virgin birth can be useful as a survival strategy, and a one-off generation of virgin births can help to keep the species going.
Dr. Sperling highlighted that it would have been incredibly difficult to have conducted their experiments on any other animal, as the Drosophila melanogaster has been the model organism for genetics research for decades, as its genes are so well understood.
She added that she hopes her work in the Department of Genetics may inform future research in her new role at the Cambridge Crop Science Centre, where she will investigate crop pests and why virgin births in insects may be becoming more common – particularly in pest species.
Dr. Sperling added: “If there’s continued selection pressure for virgin births in insect pests, which there seems to be, it will eventually lead to them reproducing only in this way.
“It could become a real problem for agriculture because females produce only females, so their ability to spread doubles.”
The females of some egg-laying animals – including birds, lizards and snakes – can switch naturally to give birth without males.
But virgin births in animals that normally reproduce sexually are rare and are often only observed in zoo animals when the female has been isolated for a long time and has little hope of finding a mate.
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