Rapid polygenic adaptation in a wild population of ash trees under a novel fungal epidemic

Abstract

Polygenic adaptation, in which selection acts on many variants at once, may serve an important role in adaptation, but it is harder to detect than selection acting on few loci of large effect. Metheringham et al. looked at genomic changes in the European ash, Fraxinus excelsior, the numbers of which have been decimated in recent decades by a fungal pathogen, Hymenoscyphus fraxineus. They found that a previously generated list of about 8000 potential variants showed significant differences in allele frequencies between juvenile and adult trees, and these differences were larger than randomly selected variants. This result suggests that polygenic adaptation may indeed be occurring in this population and that some of these variants may point to intervention targets. —Corinne Simonti