Evidence from the Genetics of Landbirds for a Forested Pleistocene Glacial Refugium in the Haida Gwaii Area

Abstract

Abstract. Pleistocene refugia likely contributed to the modern biodiversity of northern areas. Using the mitochondrial DNA cytochrome-b gene, we compared 11 forest-dwelling bird species from Haida Gwaii (formerly the Queen Charlotte Islands) with populations from Alaska, Washington, and other locations in the United States. If Haida Gwaii was an unglaciated refugium, its modern populations should feature a high number of endemic lineages and divergence times that predate the end of the last glacial maximum, ca. 13,000–19,000 years before present (ybp). Furthermore, the genetic diversity of these populations should be higher than that in areas colonized after the glacial retreat. Four of the species examined from Haida Gwaii showed old divergences and a high percentage of endemic lineages: the Northern Saw-whet Owl (Aegolius acadicus), Hairy Woodpecker (Picoides villosus), Steller's Jay (Cyanocitta stelleri), and Pine Grosbeak (Pinicola enucleator); all four have endemic subspecies on these islands. The Pa...