(CN) — Life finds a way, according to researchers that have, for the first time, induced “virgin birth” using a fruit fly species that is not normally capable of the phenomenon.
In a study published Friday in Current Biology, researchers use the fruit fly Drosophila melanogaster, which normally reproduces sexually like most animals, and altered its genes to engineer an ability to manifest a virgin birth.
According to Alexis Sperling, a University of Cambridge researcher and first author of the paper, 76% of fruit flies tested can undergo parthenogenesis to some degree, though the Drosophila melanogaster is not one of them.
Virgin birth, or parthenogenesis, is categorized by the production of offspring without a male. Rather than an embryo developing through the combination of gametes, offspring is able to develop without fertilization through meiosis. Biologists have documented that it can happen throughout all levels of the animal kingdom, from insects to reptiles and sharks and other fish.
“We induced this genetic change in Drosophila melanogaster using mutations that had been established by other researchers for other purposes or that were naturally occurring,” Sperling said in an email interview. “We combined the mutations into a single fly line using the genetic tools that were established in Drosophila decades ago called ‘Balancer Chromosomes’ and classic Mendelian crossing.”
Sperling and her team sequenced two strains of the genome of the fruit fly species Drosophila mercatorum, — which, unlike Drosophila melanogaster, are naturally capable of parthenogenesis — one that reproduced sexually and one that reproduced through virgin birth. They could then identify the genes at play during parthenogenesis.
They then altered those same genes in their model fly, the Drosophila melanogaster, switching on the ability in the similar fruit fly. According to Sperling, those flies waited for males for half their lifespan, but then gave up and proceeded with virgin births.
Offspring produced by those fruit flies, like with all virgin births, were all female and genetically similar to their mothers. The researchers also found that only 1-2% of this second generation of fruit flies had the capability for parthenogenesis, and usually only if there were no males around.
Though they have been able to induce this ability in Drosophila melanogaster fruit flies, engineering parthenogenesis in other animals remains under study.
“In almost every phylum of animals there is at least one species that is capable of parthenogenesis. Therefore, although it is not common, there are many animals that are capable of doing this, including many snakes, fish, lizards, and of course the famous crocodile from earlier in the summer,” Sperling said. “The genes that we identified in Drosophila will have homologs in other species but we do not know if altering them will cause parthenogenesis in other species. It is very likely that different genes that affect the same processes may cause parthenogenesis in other species.”
Although Sperling conducted the work in the study with Cambridge’s Department of Genetics, her recent move to the university’s Crop Science Centre with the Department of Plant Sciences has prompted investigation into crop pests and the rise of these virgin births.
“In nature, parthenogenesis at a small scale is likely to go unnoticed. However, at a large scale, for example in a green house, if this were to start happening a lot then it would become very noticeable because all things being equal, parthenogenetic females have twice the reproductive output as sexually reproducing females. The population could exponentially grow at twice the rate normally seen and become very problematic,” she said.
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