Biologists have discovered a new species of butterfly occupying Alaska's interior -- the first in 28 years. Researchers believe the hardy species is a hybrid of two ancient species uniquely adapted for life on the Last Frontier.

"Hybrid species demonstrate that animals evolved in a way that people haven't really thought about much before, although the phenomenon is fairly well studied in plants," University of Florida lepidopterist Andrew Warren said in a news release.

Warren and his colleagues suggest the Tanana arctic, Oeneis tanana, evolved from the hybridized offspring of two butterflies Chryxus arctic, O. chryxus, and the white-veined arctic, O. bore, just prior to the last ice age.

"Scientists who study plants and fish have suggested that unglaciated parts of ancient Alaska known as Beringia, including the strip of land that once connected Asia and what's now Alaska, served as a refuge where plants and animals waited out the last ice age and then moved eastward or southward from there," Warren explained. "This is potentially a supporting piece of evidence for that."

The ice age pushed the Chryxus arctic south to the Rockies, while the Tanana arctic and white-veined arctic stayed behind in Beringia. Today, the Tanana arctic prefers the spruce and aspen forests of Alaska's Tanana-Yukon River Basin.

The likeness among the new species and its relatives helped it remain unidentified for decades. But the Tanana arctic is larger and darker and boasts a scattering of tiny white freckles that give it a "frosted" appearance.

Warren and his research partners -- whose work was conducted using museum specimens -- plan to return to the Tanana-Yukon River Basin to search for new Tanana arctic specimens.

"Once we sequence the genome, we'll be able to say whether any special traits helped the butterfly survive in harsh environments," he said. "This study is just the first of what will undoubtedly be many on this cool butterfly."

Warrens also believes future monitoring of the Tanana arctic will be useful to climate scientists. Butterflies are extremely sensitive to climatic shifts.

"This butterfly has apparently lived in the Tanana River valley for so long that if it ever moves out, we'll be able to say, 'Wow, there are some changes happening,'" Warren said. "This is a region where the permafrost is already melting and the climate is changing."