Local adaptation is key for ecotypic differentiation and species evolution. Understanding the underlying genomic patterns can allow the prediction of future maladaptation. In this project, we generated whole-genome resequencing data for more than 1,000 individuals from 100 range-wide populations of European beech (Fagus sylvatica L.), an important forest tree species in Europe. We show that genetic variation closely mirrors geography. Genome-wide analyses for genotype-environment associations (GEAs) identify relatively few potentially adaptive variants after correcting for an overwhelming signal of statistically significant but non-causal GEAs. Nevertheless, we find indications of polygenic adaptation exhibiting broad- and fine-scale variation across the landscape, highlighting the relevance of spatial resolution. In summary, our results emphasize the importance, but also exemplify the complexity, of employing natural genetic variation for forest conservation under climate change. First analyses of these data can be found in this paper: Lazic et al. 2024.

European beech (Fagus sylvatica L.) trees exhibit remarkable phenotypic variation in virtually any trait that has been looked at. Importantly, a substantial part of this variation can be explained by genetics, i.e. DNA sequence polymorphisms. We work on developing different methods for high-throughput phenotyping using almost 2,000 selected beech trees growing in a common garden in Northern Germany. Notably, these trees originate from 100 natural populations from across the species range. We want to combine the phenotypic measurements with our genomic data to elucidate the genetic basis of trait variation. This may help to better predict the species response to climate change.

This project aims to elucidate the genetic basis and molecular evolution of sex determination. To this end, we use the Salicaceae family as a model system. Despite the longstanding interest in sex chromosome evolution and the underlying genetic basis, the molecular mechanisms have been identified only for a relatively small number of dioecious plants and an even smaller number of monoecious species. Contrary to the classical two-gene model of sex chromosome evolution, we demonstrated that a single gene determines sex in poplar (Müller et al. 2020). Additionally, this gene controls a highly targeted number of downstream genes, potentially explaining the minimal sexual dimorphism observed in poplars and other species (Leite Montalvao et al. 2022). Current efforts are targeted towards understanding the molecular evolution of transition between sexual systems, such as dioecy and monoecy, and whether the signaling pathways may be conserved. In summary, this project will contribute to our general understanding of the molecular genetics of plant sexual systems. 

The collaborative 'FraxForFuture' project included 27 German research institutions studying the fungal disease ash dieback, which poses an increasing threat to common ash (Fraxinus excelsior) across Europe. Within the subproject 'FraxGen' we used four single-tree progenies and 'breeding-without-breeding' to extract four large full-sibling families (with >100 individuals each). These families were genotyped using low coverage whole-genome resequencing (Krautwurst et al. 2024) to identify segregating sequence variants and generate high-density genetic maps. These genetic maps are now being combined with ash dieback phenotypes to perform QTL analyses, which will enhance our understanding of the genetic architecture of ash dieback tolerance and susceptibility.