Fruit Fly Reproduces Asexually After Genetic Modification

Fruit flies are among the most studied organisms in genetics research. They usually reproduce sexually, involving the fertilization of an egg by a sperm. However, some species of fruit flies have the ability to switch between sexual and asexual reproduction, a process called parthenogenesis.

Parthenogenesis is the development of an egg into an embryo without fertilization by a sperm. The offspring are not exact clones of their mother, but they are genetically very similar and always female. Parthenogenesis can be a survival strategy to keep the species going if there are no males around.

Researchers from Cambridge University and the California Institute of Technology have achieved a breakthrough in genetics by inducing parthenogenesis in the common laboratory fruit fly Drosophila melanogaster, which normally does not reproduce asexually. Their findings have implications for understanding the evolution of reproduction and for controlling insect pests.

The researchers identified the genes that are switched on or off when a distant species of fruit fly, Drosophila mercatorum, reproduces via parthenogenesis. They then engineered the corresponding genes in D. melanogaster, and found that the laboratory flies gained the ability to reproduce asexually. The modified flies passed on this ability to their offspring, which could reproduce either sexually or asexually.

The key genetic modifications included adding two extra copies of the polo gene, an extra copy of the Myc gene, and reducing the expression of the Desat2 gene. These genes are involved in regulating cell division, growth and differentiation.

“It was truly stunning for us to find how tripping a small number of genetic switches would enable virgin Drosophila melanogaster fruit flies to generate viable and fertile offspring just like virgins of their distant Drosophila mercatorum cousins,” said David Glover, research professor of biology and biological engineering at Caltech and senior author of the study.

The researchers also observed that parthenogenetic flies had shorter lifespans, lower fertility and higher rates of DNA damage than sexual flies. These results suggest that sexual reproduction has some advantages over asexual reproduction in terms of maintaining genome stability and longevity.

Some of the advantages of sexual reproduction over asexual reproduction are:

• Sexual reproduction creates diversity in genetic makeup, which increases the chances of adaptation and survival in changing environments.
• Sexual reproduction allows for recombination and elimination of harmful mutations, which improves the quality and fitness of the offspring.
• Sexual reproduction enhances the immune system and resistance to diseases, which reduces the risk of epidemics and extinction.

The study was published in two papers in the journals Current Biology and Heredity in 2023 and 2024 respectively .

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