Ancient DNA of NW Europe reveals responses to climate change

Andøya (69 °N) is a key area for data on terrestrial flora and vegetation in Norway during the Late Weichselian (25,000 to 10,000 years (uncalibrated) B.P.). Cores covering most of this time interval has been retrieved from several lakes, confirming the e xistence of an ice-free area potentially serving as a 'cryptic' refugium at a time when almost all of Scandinavia was covered by ice. The sediments contain small quantities of pollen of tree species (Betula, Picea, Pinus); so far interpreted as deriving f rom long distance dispersal. A recent study of ancient sediment DNA in one of the lakes yielded DNA of pine (Pinus) and spruce (Picea) dated at c. 22,000 and 17,500 cal years BP, respectively, indicating that these species possibly survived in northern in situ refugia. If the source of this DNA is confirmed as locally growing trees, this means that pine and spruce were present in Scandinavia more than 10,000 years earlier than previously assumed. Similarly, recent findings of ancient DNA of thermophilic t axa in the geographically isolated arctic archipelago Svalbard indicate that species had a more northern distribution in the Holocene hypsithermal (4000 - 8000 years BP) than today. We propose to investigate the late glacial flora of Andøya and Svalbard b y: 1) using recently developed high throughput sequencing technologies to analyse ancient sediment DNA in four new sediment cores from each of Andøya and Svalbard, 2) analysing modern lake sediments and current vegetation from the two sites to evaluate th e correlation between species frequency in the vegetation, and likelihood of representation in the sediment DNA samples, and 3) assess if the methods used for extraction and amplification of ancient sediment DNA are likely to yield DNA from pollen grains within the sediments. The results of this study will increase our understanding of how species responded to climate change in the past, which is essential to forecast effects of current global warming.