Resurrecting an Urban Sunflower Population

Resurrection experiments provide a unique opportunity to directly evaluate phenotypic and molecular evolution in response to environmental challenges. To understand evolution of an urban population of Helianthus annuus over 36 years, we resurrected samples obtained from a 1980 USDA National Plant Germplasm System accession alongside contemporary successors gathered in 2016. Changes in transcript expression using RNA-seq data revealed 200 differentially expressed transcripts between antecedent and modern groups, and transcript expression was higher in modern samples as compared to antecedent samples. Expression patterns indicated evolution due to genetic drift, crop-wild introgression, or adaptive evolution; admixture analysis was consistent with gene flow from the crop into the modern groups. The resurrection method allowed us to understand molecular and phenotypic evolution as a response to environmental pressures and gene flow from cultivated H. annuus.