Some scientific battles are epic: Think Nikola Tesla and Thomas Edison’s war of currents. Others fly under the radar, like a heated dispute over the origins of Mead’s skipper (above), a 150-year-old butterfly gathering dust on a Harvard University museum shelf. Now, using DNA from the dead insect, scientists have discovered its birthplace: a small mountain town in Colorado. The discovery settles old scores—and it could also help museum curators worldwide trace the origins of their own “lost” species.
When U.S. naturalist Theodore Mead found a tiny skipper butterfly (Hesperia colorado) in 1871, he didn’t label its location—typical for birds, insects, and other animals collected before GPS coordinates were added to most specimen tags in the early 2000s. That failure came back to haunt lepidopterists, one of whom discovered a nearly identical butterfly in the early 1980s. He classified it as a new subspecies. Other butterfly scientists were not so sanguine.
To solve the mystery of Mead’s butterfly, researchers from Texas and Florida started with its DNA. They gently removed the skipper’s abdomen from its pinned, fragile body, and extracted one-quarter of its nuclear DNA—and all of its mitochondrial genome—using a chemical solution to break down the genetic material.
They then sequenced the DNA, along with the DNA of 85 other H. colorado skippers. Next, the researchers compared each sequence to a reference genome of the species, creating a genetic “road map” that shows just how closely each specimen is related. From there, it was easy for the scientists to pinpoint the geographic origin of Mead’s skipper: Twin Lakes, Colorado, they report this month on bioRxiv.
Scientists have been using ancient DNA to trace early human remains to the places they lived for 2 decades, but this may be the first time DNA sequencing has been used to pinpoint the geographic origin of a museum specimen older than 100 years. Experts say it may not be the last. If the method can be replicated, it could soon uncover the origins of many old species that lack collection details.