Genome–environment association study suggests local adaptation to climate at the regional scale in <i>Fagus sylvatica</i>

TLDR

Long‑lived forest trees possess evolutionary potential that is essential for their local persistence amid climate change. The study uses genome‑environment association analyses to determine whether regional populations of *Fagus sylvatica* experience differential selection that could preadapt them to climate change. Researchers examined 79 natural populations, genotyping 12 SSR markers for neutral variation and 144 SNPs from 52 candidate genes, and related these to 87 environmental variables using latent‑factor mixed models, logistic regressions, and isolation‑by‑distance/environment tests. SSR data revealed only short‑range relatedness and no large‑scale genetic structure, while GEA identified 16 SNPs in 10 genes linked to environmental predictors and isolation‑by‑environment, supporting adaptation to water availability and temperature and suggesting gene flow spreads advantageous alleles, thereby potentially reducing regional extinction risk under climate change.

Abstract

Summary The evolutionary potential of long‐lived species, such as forest trees, is fundamental for their local persistence under climate change ( CC ). Genome–environment association ( GEA ) analyses reveal if species in heterogeneous environments at the regional scale are under differential selection resulting in populations with potential preadaptation to CC within this area. In 79 natural Fagus sylvatica populations, neutral genetic patterns were characterized using 12 simple sequence repeat ( SSR ) markers, and genomic variation (144 single nucleotide polymorphisms ( SNP s) out of 52 candidate genes) was related to 87 environmental predictors in the latent factor mixed model, logistic regressions and isolation by distance/environmental ( IBD / IBE ) tests. SSR diversity revealed relatedness at up to 150 m intertree distance but an absence of large‐scale spatial genetic structure and IBE . In the GEA analyses, 16 SNP s in 10 genes responded to one or several environmental predictors and IBE , corrected for IBD , was confirmed. The GEA often reflected the proposed gene functions, including indications for adaptation to water availability and temperature. Genomic divergence and the lack of large‐scale neutral genetic patterns suggest that gene flow allows the spread of advantageous alleles in adaptive genes. Thereby, adaptation processes are likely to take place in species occurring in heterogeneous environments, which might reduce their regional extinction risk under CC .