Data from: Landscape genomics and a common garden trial reveal adaptive differentiation to temperature across Europe in the tree species Alnus glutinosa

The adaptive potential of tree species to cope with climate change has
important ecological and economic implications. Many temperate tree
species experience a wide range of environmental conditions, suggesting
high adaptability to new environmental conditions. We investigated
adaptation to regional climate in the drought-sensitive tree species Alnus
glutinosa (Black alder), using a complementary approach that integrates
genomic, phenotypic and landscape data. A total of 24 European populations
were studied in a common garden and through landscape genomic approaches.
Genotyping-By-Sequencing was used to identify SNPs across the genome,
resulting in 1990 SNPs. Although a relatively low percentage of putative
adaptive SNPs was detected (2.86% outlier SNPs), we observed clear
associations among outlier allele frequencies, temperature, and plant
traits. In line with the typical drought avoiding nature of A. glutinosa,
leaf size varied according to a temperature gradient and significant
associations with multiple outlier loci were observed, corroborating the
ecological relevance of the observed outlier SNPs. Moreover, the lack of
isolation-by-distance, the very low genetic differentiation among
populations and the high intra-population genetic variation all support
the notion that high gene exchange combined with strong environmental
selection promotes adaptation to environmental cues.