Differentiation and admixture of Fagus sylvatica L. and Fagus orientalis Lipsky in a northern German forest – learning from pioneer forest work

Tree species are suffering from changing and stressful environmental conditions worldwide. Fagus sylvatica L., one of the most common Central European deciduous tree species showed symptoms of crown damage, a reduction in growth and increased mortality following the severe recent drought years. For Germany Fagus orientalis Lipsky, a closely related species with higher drought tolerance, originating from south-eastern Europe, Turkey, the Greater Caucasus region and the Hyrcanian forest, has been proposed as an alternative with high future potential. The translocation of pre-adapted planting material has been proposed as a tool to mitigate negative effects of climate change. This approach can be beneficial but might also harbor risks. Taking advantage of F. orientalis trees planted over 100 years ago in the forest district of Memsen, Germany, we set out to study admixture between the two beech species and the direction of gene flow. Furthermore, we used a range-wide dataset of F. sylvatica and F. orientalis provenances to determine the origin of the introduced trees. Using a combination of nuclear EST-SSRs and one chloroplast SSR marker with species-specific variants, we could show that interspecific gene flow was going in both directions. In most cases, F. sylvatica was the pollen donor which is likely explained by the higher abundance of this species producing vast amounts of pollen. The planted trees originated from the Greater Caucasus region and showed strong genetic divergence from German F. sylvatica populations. In the future, gene flow patterns as well as hybrid performance from different provenances should be tested in additional stands and in comparison to F. sylvatica provenances from southern Europe to assess the suitability of Oriental beech for the mitigation of climate change impacts.

[1]  E. Schulze,et al.  5S‐IGS rDNA in wind‐pollinated trees (Fagus L.) encapsulates 55 million years of reticulate evolution and hybrid origins of modern species , 2021, bioRxiv.

[2]  A. Rigling,et al.  A first assessment of the impact of the extreme 2018 summer drought on Central European forests , 2020, Basic and Applied Ecology.

[3]  C. Beierkuhnlein,et al.  High Recovery of Saplings after Severe Drought in Temperate Deciduous Forests , 2020, Forests.

[4]  Markus Müller,et al.  Characterization of EST-SSRs for European beech (Fagus sylvatica L.) and their transferability to Fagus orientalis Lipsky, Castanea dentata Bork., and Quercus rubra L. , 2018, Silvae Genetica.

[5]  T. Merou,et al.  Adaptive Diversity of Beech Seedlings Under Climate Change Scenarios , 2018, Front. Plant Sci..

[6]  D. Gömöry,et al.  Phylogeny of beech in western Eurasia as inferred by approximate Bayesian computation , 2018, Acta Societatis Botanicorum Poloniae.

[7]  S. Aitken,et al.  Time to get moving: assisted gene flow of forest trees , 2015, Evolutionary applications.

[8]  Arnold J. Bloom,et al.  Easy Leaf Area: Automated digital image analysis for rapid and accurate measurement of leaf area1 , 2014, Applications in plant sciences.

[9]  M. Whitlock,et al.  Assisted Gene Flow to Facilitate Local Adaptation to Climate Change , 2013 .

[10]  B. vonHoldt,et al.  STRUCTURE HARVESTER: a website and program for visualizing STRUCTURE output and implementing the Evanno method , 2012, Conservation Genetics Resources.

[11]  D. Winter mmod: an R library for the calculation of population differentiation statistics , 2012, Molecular ecology resources.

[12]  P. Weber,et al.  Drought-Adaptation Potential in Fagus sylvatica: Linking Moisture Availability with Genetic Diversity and Dendrochronology , 2012, PloS one.

[13]  Thibaut Jombart,et al.  adegenet 1.3-1: new tools for the analysis of genome-wide SNP data , 2011, Bioinform..

[14]  K. Dixon,et al.  Terrestrial orchid conservation in the age of extinction. , 2009, Annals of botany.

[15]  R. Finkeldey,et al.  Genetic variation of beech (Fagus sylvatica L.) in Rodopi (N.E. Greece) , 2008, European Journal of Forest Research.

[16]  R. Petit,et al.  Some Evolutionary Consequences of Being a Tree , 2006 .

[17]  G. Evanno,et al.  Detecting the number of clusters of individuals using the software structure: a simulation study , 2005, Molecular ecology.

[18]  J. Goudet HIERFSTAT , a package for R to compute and test hierarchical F -statistics , 2005 .

[19]  V. Storme,et al.  Gene flow between cultivated poplars and native black poplar (Populus nigra L.): a case study along the river Meuse on the Dutch-Belgian border , 2004 .

[20]  O. Gailing,et al.  Spatial Distribution of Genetic Variation in a Natural Beech Stand (Fagus sylvaticaL.) Based on Microsatellite Markers , 2004, Conservation Genetics.

[21]  R. Gardner,et al.  A set of conserved PCR primers for the analysis of simple sequence repeat polymorphisms in chloroplast genomes of dicotyledonous angiosperms. , 1999, Genome.

[22]  M. Nei,et al.  Estimation of fixation indices and gene diversities , 1983, Annals of human genetics.

[23]  M. Nei Analysis of gene diversity in subdivided populations. , 1973, Proceedings of the National Academy of Sciences of the United States of America.

[24]  M. Krawczak,et al.  Genetic Diversity in the , 2008 .

[25]  D. C. Malcolm,et al.  The genetic management of native species in Scotland , 1998 .

[26]  F. Lefèvre,et al.  The conservation of Populus nigra L. and gene flow with cultivated poplars in Europe. , 1995 .