Join us in congratulating AWA Vice President, Dr. John Morton, and co-authors Diana Wolf, Matthew Bowser, Naoki Takebayashi, and Dawn Magness in their recent publication in the Canadian Journal of Forest Research!
Abstract
We investigated the genetic makeup of Lutz spruce, a natural hybrid between white and Sitka spruce on the Kenai Peninsula, Alaska. Microsatellites indicate 72% of individuals sampled had predominantly white spruce ancestry whereas 14% had predominantly Sitka spruce ancestry; some individuals classified as white spruce had Sitka spruce plastid genotypes. As Picea mitochondria are maternally inherited and plastids are paternally inherited, it appears that white spruce was the ancestral seed parent of nearly all spruce on the peninsula, whereas Sitka spruce alleles originated from pollen. Pollen records show that white spruce colonized the western peninsula ~8,500 YBP from glacial refugium, whereas Sitka spruce arrived on the eastern peninsula ~4,000 YBP after migrating up the Pacific coast. Our data suggest that Sitka spruce migration onto the western peninsula may have occurred not via seed dispersal, but by long distance transport of wind-borne pollen and subsequent hybridization with established white spruce populations. Hybridization was an important mechanism that allowed Sitka spruce to expand the leading edge of its range in response to historical climate change. As the climate continues to warm, climate envelope modeling suggests Lutz spruce may ultimately displace white spruce on the western peninsula even as Sitka spruce is constrained to the eastern peninsula where it will continue to hybridize.
