Newswise — Xerces Blue Butterfly (Glaucoma) is native to the coastal sand dunes of San Francisco, USA. As the city grew, much of the butterfly’s habitat was destroyed and their populations moved to the Golden Gate National Park. Its wings are iridescent dark green, with characteristic white spots on the abdomen. The last surviving specimen of the species was found in 1941 by entomologist W. Harry Lange. It is considered to be the first insect to become extinct in historical time. Its disappearance has made it a global symbol of human-caused extinction, so much so that it has been named for a prominent American conservation association, the Xerces Society.
An earlier study, in 2022, recovered mitochondrial DNA from a specimen of the Xerces Blue butterfly and compared it to that of the Silvery Blue butterfly (Glaucopsyche lygdamus)its closest relatives, concluding that they are indeed separate species and not just distinct populations.
The study was led by Carles Lalueza-Fox, MCNB director and researcher at IBE (CSIC-UPF) and Roger Vila, researcher at IBE (CSIC-UPF), with participation from Toáms Marquès-Bonet, researcher ICREA research. at the Faculty of Medicine and Life Sciences (MELIS) of Pompeu Fabra University and IBE and Professor of the same university, and published in eLife, have successfully sequenced the genomes of four butterfly species Xerces Blue and seven species of Silvery Blue butterflies between 80 and 100 years old from the Smithsonian Institution in Washington. The researchers were able to deduce that the two species diverged between one and two million years ago and that they represent two distinct evolutionary lines.
Genome comparison of the two species revealed that the Xerces blue butterfly DNA shows a high rate of inbreeding, a marker of population decline that can be used to identify other insect species threatened by this activity. human activity and have an extinct pattern, unlike those species. of vertebrates, is currently unknown. It could also pave the way for the extinction of this common butterfly, a project that has been of interest to the scientific community for many years.
Xerces Blue genome reveals its extinction story
The results of the study indicate that the Xerces Blue butterfly has experienced massive population decline over tens of thousands of years, possibly due to climate change not affecting Silvery Blue. However, human destruction of its habitat caused its eventual extinction.
This is the conclusion of the study after finding features in its genome that are typical for a small population, including low genetic diversity, long chromosome segments with no genetic variation, and low frequency. a high number of harmful alleles, reducing the viability of individuals and rendering it what we would call a vulnerable species.
Genomic clues could save other endangered insects
The Xerces Blue butterfly is a symbol of the global insect extinction. Now its genome could help stave off the extinction of other endangered insect species whose plummeting populations aren’t immediately apparent.
IBE (CSIC-UPF) researcher Roger Vila, who co-led the study, explains: «It’s easier to spot endangered mammal species because in many cases it can be counted get individuals». «However, there are many species of endangered insects whose status goes unnoticed because it is difficult to examine their populations, which to us appear to be abundant. However, they do. can be very sensitive to climate changes and human actions, such as For this reason, we believe that genomic features that signal the decline of Xerces butterfly populations may play a role alert and help us detect vulnerable insect species in future studies.»
Knowing the whole genome is the first step towards extinction
The disappearance of insects, especially pollinators, is a very serious global ecological problem. Therefore, the extinction of species such as the Xerces Blue butterfly, using CRISPR-based genetic engineering techniques, is of great concern to the scientific community.
«The Xerces Blue butterfly is a good candidate for extinction because it is a relatively recent disappearing insect, so the ecological impact of its reappearance is reduced and there is no pest risk. or over-proliferate due to the limited emergence of adults (March to April) and their ecological expertise, so we would expect a complete genome of it could help with future anti-extinction initiatives,» said Carles Lalueza-Fox, researcher and director of the IBE (CSIC-UPF). Museum of Natural Sciences in Barcelona, who co-led the research.
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