Butterfly genomes have barely changed for 250m years, study reveals

The genomes of butterflies and moths have remained largely unchanged for more than 250m years despite their enormous species diversity, according to a new study published in the journal Nature Ecology & Evolution.

In the face of rapid environmental changes in the 21st century, the researchers said the analysis gives clues as to how Lepidoptera – the order of winged insects that contains butterflies and moths – have been so resilient throughout dramatic changes on Earth.

Researchers at the Wellcome Sanger Institute and the University of Edinburgh looked at more than 200 genomes – a complete set of the genetic information needed to build and maintain an organism – of butterflies and moths to better understand their evolutionary history. They traced the genetic code back to the very first butterflies and identified 32 ancestral chromosomes that are the building blocks of nearly all lepidopterans.

Prof Mark Blaxter, the senior author of the study and the head of the Tree of Life programme at the Wellcome Sanger Institute, said: “All life is connected by a common thread – DNA. Our DNA sequences record our deep history. We were able to look at the evolutionary history of butterflies through their genome to go back to their common ancestor, to the great-great-great-etcetera-grandmother of all butterflies. We found they had been remarkably stable.”

He added: “There is a contrast between the butterflies that have 16 times as many species as mammals but have a much more stable genetic foundation. It’s just amazing!”

Lepidoptera is among the most diverse animal groups known to science, making up approximately 10% of living organisms on Earth. Most moths and butterflies species today have 31 chromosomes, but a rare subset of species that includes the chalkhill blue butterfly, common during the British summer, has 90, the scientists found – breaking the species groups’ genetic norms.

Charlotte Wright, the first author and a PhD student at the Wellcome Sanger Institute, said: “The bigger question we are trying to understand is how biodiversity evolves at a broader scale. We want to know what the biggest features are from its genome that underlie the success of moths and butterflies. How can we make sense of the fact that this group makes up 10% of described species? What makes it different from other species groups that are nowhere near as successful?”

The researchers said their findings can help with conservation efforts for the species amid a rapid loss of the planet’s biodiversity, which some scientists have called the sixth mass extinction. Many insect species, including crucial pollinators, are experiencing alarming declines. Research by Butterfly Conservation released in 2023 found that since 1976, butterfly species have vanished from almost half of the places where they once flew in the UK.

The researcher team said lepidopterans were powerful indicators of ecosystem health – and that a deeper understanding of butterfly and moth biology will inform future research on adaptation for biodiversity conservation.

“When the human genome was released in 2010, it was still in millions of pieces and we had stitched those pieces together but there were still many gaps in the letters of the code,” Blaxter said. “There were jigsaw pieces missing. With the butterfly genomes, we have all of the pieces. For the majority of the species we have looked at, it is the first time we have had a genome at all.”

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