Scientists discover secret of virgin birth, and switch on the ability in female flies

Scientists have successfully induced virgin birth in the fruit fly Drosophila melanogaster, an animal that typically reproduces sexually, for the first time.

This fruit fly's capacity to reproduce either sexually or by virgin birth in the absence of males is handed down through the generations once it has been activated.

The majority of animal reproduction is sexual, including the fertilization of a female's egg by a male's sperm. The process by which an egg develops into an embryo without being fertilized by sperm—a male is not required—is known as "parthenogenesis," or "virgin birth."

The children born to virgins are never identical clones of their mothers, although they are genetically quite similar.

It was thrilling to watch a virgin fly produce an embryo that could grow to adulthood and then repeat the process, said Dr. Alexis Sperling, a researcher at the University of Cambridge and the paper's first author. "We're the first to show that you can engineer virgin births to happen in an animal," she added.

"In our genetically altered flies, the females searched for a male for about 40 days, or half of their lives, before giving up and giving birth to a virgin," she continued.

Only 1-2% of the second generation of virgin-producing female flies gave birth throughout the studies, and this only happened when there were no male flies around. The females reproduced normally when males were present by mating and becoming pregnant.

A survival tactic could be to switch to virgin birth: Virgin births in a single generation can help the species survive.

The findings was released in the journal Current Biology today.

In order to arrive at their conclusions, the researchers first sequenced the genomes of two strains of the fruit fly Drosophila mercatorum. While the other strain solely reproduces through virgin birth, the first strain need males to do it. The genes that were turned on or off when the flies reproduced without dads were found by the researchers.

The researchers changed what they believed to be the appropriate genes in the model fruit fly, Drosophila melanogaster, using the candidate genes for virgin birth capacity found in Drosophila mercatorum. Drosophila melanogaster successfully achieved virgin birth at an unexpected time.

Over 220,000 fresh fruit flies were used in the study, which took six years to complete.

The fact that this research was carried out in Drosophila melanogaster, which the researchers claim would have been extremely challenging in any other animal, was crucial to the finding. Since more than a century ago, this fly has served as the "model organism" for genetics research, and its genes are widely known.

Sperling, who conducted this research at the Department of Genetics, recently relocated to the Cambridge agricultural Science Centre to study on agricultural pests. Sperling eventually plans to look into why virgin birth in insects, especially in pest species, may be becoming increasingly prevalent.

"Insect pests will ultimately stop reproducing in any other way if there is ongoing selection pressure for virgin births, which it appears there is. Females only spawn females, which increases their potential to spread, which might become a serious issue for agriculture, according to Sperling.

Some egg-laying species, such as birds, lizards, and snakes, have natural reproductive shifts that allow them to give birth without male partners. However, virgin birth in sexually reproducing animals is uncommon, sometimes only seen in zoo animals, and typically occurs when the female has been isolated for a prolonged period of time and has little chance of finding a partner.