MUSEUM OF POSTNATURAL HISTORY
SYNTHETICA
synthetic species
This crippled fly, with pale, shrunken eyes, belongs to the species Drosophila synthetica, arguably the world’s first “synthetic” animal species—that is, one artificially created through genetic modification. In an era of unprecedented manipulation of life, this idea no longer seems far-fetched. But can a species truly be "created" in a laboratory?
First, one must understand what a species actually is. At school, we are taught to recognize a species when individuals within a group resemble each other and can produce fertile offspring. In reality, the living world pays little attention to our morphological or biological criteria. A species is a concept—a mental construct. It’s a linguistic convention used by scientists to refer to a genealogical segment of life. What actually exists in nature are reproductive barriers, which prevent organisms that are too different from breeding together. But can such a barrier be artificially created? That was precisely the challenge taken up by Spanish geneticist Eduardo Moreno. In 2012, he succeeded, using synthetic biology. In his laboratory at the University of Bern, he designed a genetic circuit—much like an engineer building an electronic circuit—to create reproductive isolation between the synthetic flies and the original population from which they were derived (Drosophila melanogaster).
Drosophila synthetica
Crédit : EPFZ, C. Felsner.
The geneticist Moreno in his laboratory in 2012.
Photo credit: Moreno
The genetic circuit operates using a “killing module” and a switch that turns it on or off. The ON/OFF state of the module is controlled by the presence or absence of a key protein. In the synthetic flies, the gene responsible for this protein is mutated. In its absence, the killing module remains off. However, if a synthetic fly mates with a non-modified one, the module is activated because the hybrid offspring inherit a functional gene that produces the key protein. Its presence triggers a cascade of genetic sequences that ultimately leads to the individual’s death at the pupal stage. This system, with components that interact in a reliable and predictable way, prevents synthetic flies from interbreeding with the original population, while still allowing them to produce fertile offspring among themselves.
The goal of this experiment was to serve as a proof of concept: to demonstrate that it is indeed possible to create a new speciation barrier. But does that mean a new “species” has been created? To answer that, one would first have to see whether this newly branched segment of the tree of life can persist over time. This has not yet been studied—and could not have been, since ten years after the experiment, the Drosophila synthetica population was presumed extinct. The fly stocks, having become irrelevant to ongoing research projects, had been discarded. However, a remnant population was recently found in a few tubes from a backup collection, tucked away in a corner of the fly facility. It turns out that Moreno’s wife—herself a geneticist—, known, in his own words, for “keeping old, sentimental things for no practical reasons, but which, in due time, make everyone happy to rediscover and end up proving useful,” had continued caring for a small stock of flies.
Perhaps one day we will know whether Drosophila synthetica truly deserves to be considered a new species. In the worst-case scenario, it should be relatively easy to recreate, given its synthetic nature.
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