Virgin birth at Cambridge thanks to genetically modified fruit flies
By decoding a genetic process responsible for asexual reproduction, researchers induced virgin births for the first time in a normally sexual fruit fly species. It was then discovered that the remarkable trait was passed down to all of the flies' daughters. The finding could help scientists find new ways to protect crops from insect pests that are increasingly able to reproduce without mates.
In arriving at their breakthrough, researchers at the University of Cambridge worked with over 220,000 fruit flies during the course of six years. To hunt down the genes responsible for virgin birth in the insects, the team examined two strains of another fruit fly species known as Drosophila mercatorum. One of these strains is only able to reproduce sexually, but the other is capable of virgin birth, a trait known as parthenogenesis. By comparing the genetic code of both strains, the scientists were able to figure out which genes were involved in virgin births.
Then they switched the corresponding genes on or off to match in the Drosophila melanogaster flies, and saw success. The subject flies could suddenly reproduce asexually, although they could only have females that were nearly clones of their parents. In the studies, the flies waited about 40 days – which represents about half of their lives – to find a male mate and when none was around, they reproduced asexually.
Interestingly, all of the daughters from the genetically modified bugs also retained the ability to have virgin births, although only 1 to 2% of them engaged in the behavior, and only after no males were present. Otherwise they mated and gave birth as usual.
"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," said Dr. Alexis Sperling, a researcher at the University of Cambridge and first author of the paper.
The researchers say that it's extremely rare to see virgin births in animals that can reproduce sexually, noting that it's sometimes seen in female zoo animals that have been left in isolation for long periods of time. However, when some species are under pressure to survive, they can evolve an asexual mode of reproducing. In fact, Sparing plans to use this work to build on research into why virgin births in insects – especially in pest species – is starting to increase around the world.
"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," said Sperling. "It could become a real problem for agriculture because females produce only females, so their ability to spread doubles."
Sperling and her team also point out that while their research may be a first, it may not translate to other animals. That's because the Drosophila melanogaster has been used in research for over a century, and has a genetic code that is extremely well understood. In fact work with the species has led to a possible understanding of extending lifespans; learning more about the effects of zero gravity on the body; tracking the impact of microplastics on health; and offering a possible way forward when dealing with erasing traumatic memories.
The research findings have been reported in the journal, Current Biology.
Source: University of Cambridge