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.
