Divergent pattern between phenotypic and genetic variation in Scots pine - Results from seedlings exposure to freezing temperatures

In this study, we sampled 54 Scots pine populations from the Norwegian coast over the Arctic Circle to western Russia covering 47.3 longitudes or more than 1/8th of the earth’s circumference, which represents the most comprehensive coverage of Northern Europe to date. We inferred variation in autumn phenology and dormancy progression from freeze hardiness tests conducted on >5000 seedlings, of which >900 seedlings from 24 populations were genotyped using genotyping-by-sequencing (GBS). Our main goal was to evaluate adaptive responses in Scots pine at phenotype and genotype levels. Evaluation of cold hardiness along environmental and geographical gradients would contribute to an understanding of the performance of these gradients for predicting freeze damage levels. The genotype data allow evaluation of genetic variance across landscapes and thus shed light on the degree of genetic-environmental association and the recolonization history of Scots pine in Scandinavia. The resulting damage levels (Damage) from exposing seedlings to freezing temperature. The damage levels were scored between 1 to two weeks after exposure to allow discoloration. A 0 damage level meant no discoloration while 6 was completely discolored or dead. Damage levels were rank normalized (DamageN) across replications (Repl).