New Genetic Evidence for the Lateglacial History of the Scots Pine (Pinus sylvestris L.) in Southern Lithuania: The Pamerkiai Case

This paper presents new ancient DNA (aDNA) results from a Scots pine (Pinus sylvestris L.) megafossil dated to the earliest intervals of the Lateglacial Interstadial (13,786–13,500 cal yr BP (calibrated years before present)). The investigated trunk was discovered between sediment layers at the Pamerkiai Outcrop in southern Lithuania, an area situated within the marginal zone of the Late Weichselian Glaciation. To date, this is the oldest megafossil successfully subjected to aDNA analysis in the eastern Baltic region. Nuclear microsatellite (nSSR) analysis indicates a strong genetic affinity to the northern genetic lineage, supporting the hypothesis of Scots pine expansion from a “Northern Refugium” (50–55° N; 35–45° E) into present-day southern Lithuania during the initial afforestation stages of the Lateglacial Interstadial. Consequently, these findings support a model involving two glacial refuge sources for Scots pine in the eastern Baltic region during the Lateglacial. Furthermore, the aDNA results demonstrate a close genetic association between this ancient sample and present-day Scots pine populations typical of wetland environments, suggesting the prevalence of a wetland palaeoenvironmental regime at the site during the earliest stages of the Lateglacial Interstadial.