eLife assessment
This important study offers new insight into how floral and reproductive phenotypes and gene expression evolve in allopolyploids. The authors marshal compelling evidence, using well-constructed genetic lines, RNA sequencing, and phenotypic analyses to distinguish the roles of hybridization, whole genome duplication, and subsequent evolution in phenotypes associated with the selfing syndrome and in gene expression. The work will be of interest to researchers working in plant speciation and genomics, as well as those more broadly interested in the effects of genome copy number on phenotypic and expression evolution.