Population genetic insights for climate-adaptive oak management: Results from a large-scale study of Turkey oak populations

Human-assisted translocation of oak reproductive material as part of climate-adaptive oak management has long been a key consideration in Central Europe. In this study, we conducted population genetic analysis of 32 Turkey oak ( Quercus cerris L.) populations from Central and Southeast Europe, using ddRAD-seq genotyping, to support forestry adaptation measures. Our results revealed multiple genetic groups within the sampled range, suggesting that long-distance transfers of reproductive material could lead to the admixture of genetically distinct groups. We also detected a diversity cline, with genetic diversity increasing from the southwest and southeast toward the northwest. The highest diversity was observed in the Carpathian Basin, which is the most continental part of the sampled range and includes many populations near the species’ drought limit. In this region, the surplus of genetic diversity may play a crucial role in local adaptation. Our findings further suggest that transferring reproductive material from Southeast Europe to the Carpathian Basin should be approached with caution, as this direction runs counter to the observed diversity gradient. Furthermore, loci under selection and their genotype-environment associations indicate that Turkey oak is primarily challenged by temperature fluctuations and extremes, rather than by water availability, as previously observed in co-occurring sessile oak ( Q. petraea (Matt.) Liebl.). These results provide valuable support for a detailed assessment of Turkey oak’s adaptive capacity, improving the efficiency of provenance selection for climate-adaptive forest management. • Genetic diversity cline found in Turkey oak across Central and Southeast Europe. • Diversity increases from southeast and southwest towards the northwest. • Admixture boosts genetic diversity in northwestern populations. • Seed transfer and assisted migration plans run counter to diversity gradient. • Genetic data help assess the need for and improve effectiveness of assisted migration.