Dr. Mikkel Winther PEDERSEN Ancient Environmental DNA and The Arrival of the Arctic Tundra Biome in Greenland
EEB External Seminar Series
12h
Le séminaire du Dr. Mikkel Winther Pedersen (University of Copenhagen, Danemark) aura lieu dans la salle de Conférence, IBENS 46 rue d’Ulm 75005 Paris
Ancient environmental DNA (aeDNA) from silty basal ice at Camp Century (Greenland) documents tundra ecosystems preserved from at least two discrete Pleistocene interglacial intervals. Using shotgun metagenomics, DNA damage profiling, and molecular dating of chloroplast sequences, we resolve two temporally distinct depositional components : an older Lower Camp Century unit (Unit 1) with elevated damage and a younger Upper Camp Century suite (Units 2–5) with lower damage. Taxonomic assemblages shift vertically from Dryas-, Salix- and Saxifraga-dominated open shrub–herb tundra in Unit 1 to communities increasingly dominated by Cassiope, Saxifraga and mosses in overlying units ; intermittent signals of shallow freshwater macrophytes (Utricularia, Elatine, Hippuris) indicate local hydrological complexity during the younger interval. Together, these data provide some of the first direct molecular evidence that a fully tundra-dominated biome was not established in Greenland until mid-Pleistocene and that interglacial intervals supported internally differentiated tundra communities comparable to modern Arctic analogues. The Camp Century record highlights the value of subglacial archives for constraining ice-sheet retreat, ecosystem assembly, and the tempo of biome reorganization, and it suggests greater resilience and ecological plasticity of Arctic plant communities during past warmings, insights that bear on projections of future ecosystem responses to rapid climate change.