Glacial refugium in Fennoscandia? : Signals in mitochondrial DNA of Pinus sylvestris

• Main Author: Bäckman, Hanna
• Format: Bachelor Thesis
• Language: English
• Published: Umeå universitet, Institutionen för ekologi, miljö och geovetenskap 2020
• Subjects: Pinus sylvestris; genetic diversity; glacial refugia; mitochondrial DNA; Natural Sciences; Naturvetenskap; Lofoten; Norway; Fennoscandia; Fennoscandian; Ice Sheet
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-176673

During the climate oscillations of the Pleistocene an ice sheet formed covering Fennoscandia. Traditionally, Scots pine and many other species were believed to have persisted in glacial refugia in the south, only returning to northern latitudes as the ice retreated. Recent studies have demonstrated the existence of glacial refugia in higher latitudes, in fact, cryptic refugia as far north as Lofoten have been suggested. I investigated the potential existence of such a refugium for Scots pine using mtDNA markers Nad 1-B/C, Nad 7-1 and NODE_new_663. Results show an east/west distribution of the mtDNA polymorphisms at Nad 1 and Nad 7 across Fennoscandia, where multi-locus mitotype bb is more common in the east and ba is more common in the west, in accordance with the hypothesis of a glacial refugium in northeast Europe. Further, the bb mitotype was discovered to be more widespread in Fennoscandia than previously documented. No unique mitotype was discovered in northwestern Fennoscandian populations to support the hypothesis of a glacial refugium along the northwest coast of Norway. Genetic diversity was high and even across Fennoscandia and differences in diversity were not significantly correlated with distance between populations, possibly due to high mutation-rates for the NODE_new_663 minisatellite locus or as a result from admixture between multiple glacial refugia in the area. No conclusive evidence regarding the existence of a glacial refugium in Fennoscandia was discovered and needs to be studied further.