Researchers have identified the genes that are switched on, or switched off, when these flies reproduce without fathers. Credit: Jose Casal and Peter Lawrence
Key Points:
- Scientists have pinpointed a genetic cause for virgin birth for the first time.
- Researchers were able to induce virgin birth is the model fruit fly, Drosophila melanogaster.
- While the virgin birth ability can save a species in crisis, it could become a problem in the future with an entire species of only females.
Pinpointing a genetic cause for virgin birth for the first time, scientists have managed to induce sperm-free birth in the fruit fly Drosophila melanogaster, an animal that usually reproduces sexually.
The research project took six years to complete with over 220,000 virgin fruit flies.
For the study, published in Current Biology, researchers at the University of Cambridge first sequenced the genomes of two strains of another species of fruit fly, Drosophila mercatorum. One strain needs males to reproduce, the other reproduces only through virgin birth. The team identified the genes that were switched on or off when the flies were reproducing without fathers.
With the candidate genes for virgin birth ability identified in Drosophila mercatorum, the researchers altered what they thought were the corresponding genes in the model fruit fly, Drosophila melanogaster. It worked: Drosophila melanogaster suddenly acquired the ability for virgin birth.
The scientists also discovered that once the ability is induced in the fruit fly, it is passed on through generations—meaning the offspring can reproduce either sexually if there are males around, or by virgin birth if there aren’t. The offspring of a virgin birth are not exact clones of their mother but are genetically very similar, and are always female.
Switching to a virgin birth can be a survival strategy. For example, a one-off generation of virgin births can help to keep the species going. However, if the action becomes more persistent, it could be a problem.
“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,” said Alexis Sperling, a researcher at the University of Cambridge and first author of the paper.