The Satyrium semiluna, or half-moon hairstreak, is a small gray butterfly that looks like a moth at first glance. The wildflower lovers are widespread across North America, from the Sagebrush steppe to the montane meadows of the Rocky Mountains.
But tucked away in the southeastern corner of Alberta, Canada, another colony of butterflies flaps across the Blakiston Fan landform of Waterton Lakes National Park.
Until now, they were thought to be a subpopulation of half-moon hairstreaks — until scientists made a phenomenal discovery: They were a new species of butterfly that had hidden in plain sight for centuries.
The researchers, who recently published their findings in the scientific journal ZooKeys, defined the new species as Satyrium curiosolus.
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“We propose ‘curiously isolated hairstreak’ as the common name due to its disjunct and unusual distribution,” Zachary G. MacDonald, lead author and postdoctoral fellow at the University of California, wrote in the study.
MacDonald said that there was “no evidence of contemporary or recent gene flow” between the half-moon hairstreak and the curiously isolated hairstreak.
Absence of gene flow, which is the transfer of genetic material from one population to another, indicated that the latter had evolved in isolation.
“Satyrium curiosolus is completely isolated today, and coalescent-based analyses suggest this isolation may extend up to 40,000 years,” MacDonald concluded.
In a press release for Association of Zoos & Aquariums, the Wilder Institute emphasized the importance of the discovery: “Far more than a taxonomic update, this discovery reveals a lineage shaped by 40,000 years of evolutionary solitude — an ancient survivor tucked away in one of Canada’s most iconic and ecologically rich landscapes.”
The research, which was funded in part by the Calgary Zoo Foundation and Parks Canada, was applauded by Dr. James Glasier, a conservation population ecologist at the Wilder Institute and Calgary Zoo.
Glasier noted that butterfly species had been uniquely shaped by 40,000 years of isolation in Alberta.
“With its official recognition as a distinct species, the curiously isolated hairstreak is a powerful example of how long-term isolation shapes biodiversity,” Glasier said on behalf of the Calgary Zoo.
“But its rarity and extreme specialization also make it incredibly vulnerable — there’s no fallback population to sustain its survival.”
Due to its isolated habitat, on the grasslands of Blakiston Fan, MacDonald cautioned that the new species’ “low genetic diversity” may hinder its ability to adapt to “accelerating climate change.”
So, he proposed a solution: Genetic rescue — a conservation strategy that involves increasing the genetic variation of a population via breeding.
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“Genetic rescue can introduce beneficial genomic variation that is integral to rapid adaptation, and hybrid vigor has long been recognized as a possible benefit of hybridization, even between distinct species,” MacDonald explained.
“Hybridization is common between species, and should not always be viewed as undermining species-level recognition,” he added. “The possibility of genetic rescue should be regularly revisited as local climatic and habitat conditions at Blakiston Fan continue to change.”
In an interview with CBC News, MacDonald said that this discovery was “just the tip of the iceberg.”
“I think what's most interesting to us is: What do we do about the conservation of this highly endangered species now?”
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Header image via Jan Mosimann (CC BY-ND 2.0)
