Résumé
Forests are ecosystems where naturally multiple tree species may coexist. Assessing possible tree behavior to ongoing climate change is key to forecast forest's future, and better understanding the links between tree community assembly and functioning is essential to this aim. Here we compared genomes of beech trees growing either in monospecific or multispecific plots, in different sites in the French Alps. We found a high genetic association at specific loci between SNP profiles and the monospecific or multispecific tree community composition. The studied mixed forests appear as genetic patchworks structured at the sub-population level. The most significant SNPs identified point out a key metabolic pathway, pathogen defense related genes and stress response. As mixed forests are likely to better promote biodiversity conservation and forest ecosystem functions provision and to show a stronger resilience to new climate conditions, our findings strengthens the need of understanding multispecific tree community assembly at the genetic level to forecast and improving forest adaptation to climate change.