The blue xerces butterfly, considered the first species of insect to become extinct in historical times due to human action, could return to life in the near future. This is the reading made by the scientists from the Institute of Evolutionary Biology (IBE, CSIC-UPF) who have managed to completely sequence its genome, a milestone never before achieved with an extinct insect. The researchers who have led the study also hope that the DNA details will allow an assessment of the conservation status of current insect species.
The disappearance of insects is a serious ecological problem worldwide, so having the possibility of de-extinguishing species such as blue xerces (Glaucopsyche xerces) is of great interest to the scientific community. Techniques for returning extinct species to the world have not yet been developed, and the butterfly is an ideal candidate for doing so.
"This is an insect that disappeared relatively recently, so the ecological impact of its reappearance is reduced," says Carles Lalueza-Fox, director of the Museu de Ciències Naturals de Barcelona (MCNB) and one of the leaders of the research. . In addition, he points out, the butterfly lived in a very small ecosystem and the adults appear only a few weeks a year, between March and April, so the risk of it becoming a pest is very low.
However, underlines the also IBE researcher, having sequenced the genome is only a first step in proposing the extinction of a species. "The way is open to try it", but "there are enormous technical difficulties", although he hopes that in about five years it will be viable to carry out a first test.
De-extinction would involve altering some genes of the silvery blue butterfly (Glaucopsyche lygdamus), the closest relative to the extinct species, using the CRISPR genetic editing tool, a kind of molecular scissors that allows you to cut and paste pieces of genetic code. The question is to identify which are the key genes that must be changed. "There are changes that are not of any importance and, on the other hand, there are others that are important," explains Roger Vila, IBE researcher and co-leader of the study. "Knowing to what extent a gene is more or less important is something that should be clarified," he says.
Preliminary studies carried out by scientists estimate that there are approximately two hundred genes that would have to be altered, a major challenge but a priori possible. “It is not the same to use the technique to change a specific gene than so many markers”, points out Vila.
The possibility of de-extinction also opens ethical gaps. Experts point out that the priority should always be to avoid extinction, and that reintroducing an extinct species leaves questions. “To what extent could we exactly recreate the species? Would it be feasible to reintroduce it? Would climate change currently affect it? What ecological interactions does it need to survive? If it has already gone extinct once, what should we do in the habitat so that it doesn't go extinct?” asks Roger Vila.
The doubts are legitimate, because despite the fact that the human being dealt the final blow by destroying its habitat, the study led by the IBE and published today in the eLife magazine, has revealed that the blue xerxes was already in danger of extinct for many years.
The complete sequencing of the genome of the four specimens analyzed has made it possible to reconstruct the history of the extinct species. Its population grew until about 100,000 years ago, when the butterfly "probably became isolated" in the coastal dunes of San Francisco, the result of the glacial periods that occurred then. Their numbers began to dwindle and "later the human being finished it off," sums up the director of the Museu de Ciències Naturals de Barcelona.
The specimens studied had high levels of consanguinity: they showed little genetic diversity and many mutations detrimental to their reproduction, clear indicators that the species had been in decline for years and did not have a good prognosis. "It is something that happens with many endangered species," says the expert, "for hundreds or thousands of years their demographic numbers are falling, and in the end all the individuals are related."
These indicators open the possibility of assessing the conservation status of current insects. "Extrapolating the results of the study to other insects, we hope that the combination of low genomic diversity and historically low population sizes is indicative of a high vulnerability to extinction and, therefore, of the need to implement conservation programs," he states. Daniel Sol, a CSIC researcher at the Center for Ecological Research and Forestry Applications (CREAF), and an expert in evolutionary ecology, who has not participated in the research.
