By Sid Perkins
Genetic analysis of white spruce trees at sites across North America suggest that that species endured the harsh climate of Alaska throughout the last ice age, a notion that scientists have debated for decades.
Picea glauca, the white spruce, is one of the most common trees in Alaska’s forests today, says Lynn L. Anderson, a plant geneticist at the University of Illinois at Urbana–Champaign. However, scientists haven’t unearthed Alaskan fossils of that species dating from the most recent ice age, which lasted from 25,000 to 12,000 years ago. During that time, most of Alaska was either a treeless tundra or covered in ice. The lack of white spruce fossils led some researchers to speculate that the species was wiped out in Alaska during the ice age and that trees from elsewhere recolonized the region once the climate warmed.