The current PhD position will focus on understanding the adaptive and demographic processes that have led to the range expansion of European beech (Fagus sylvatica L.) after the last glacial maximum both at the genomic and phenotypic level. Fagus sylvatica is best considered as a species complex whose current range extends from the Pyrenees to northern Iran. Despite the large genetic diversity of beech populations in Minor Asia and on the Balkan peninsula, a single lineage has colonized most of Europe. Had the colonizing lineage have superior performance, and does it outperform other lineages still today? Could current beech die-back across Europe be partly attributed to the reduced genetic diversity due to the expansion load or is it due to ongoing unprecedented climate change? Could the introduction of other beech lineages and hybridization between them be used to mitigate future climate change? The selected PhD student will investigate these questions using a combination of genomics, common garden experiments (performed by foresters) and environmental data.