Both functional trait divergence and trait plasticity confer polyploid advantage in changing environments

ABSTRACT Polyploidy, or whole genome duplication, exists in all eukaryotes and is thought to drive ecological and evolutionary success especially in plants. The mechanisms of polyploid success in ecologically relevant contexts, however, remain largely unknown. Here we conducted an extensive test of functional trait divergence and trait plasticity in conferring polyploid fitness advantage in changing environments by growing clonal replicates of a worldwide genotype collection of six polyploid and five diploid wild strawberry ( Fragaria ) species in three climatically different common gardens. Among leaf functional traits, we detected divergence in means but not plasticities between polyploids and diploids, suggesting that increased genomic redundancy does not necessarily translate into broader phenotypic amplitude in polyploids. Across the heterogeneous garden environments, however, polyploids exhibited fitness advantage, which was conferred by both trait means and adaptive trait plasticities, supporting a ‘jack-and-master’ hypothesis for polyploids. Our findings provide unparalleled insight into the prevalence and persistence of polyploidization.