Abstract
Summary Polyploidy, or whole‐genome duplication often with hybridization, is common in 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.We conducted an extensive test of functional trait divergence and plasticity in conferring polyploid fitness advantage in heterogeneous environments, by growing clonal replicates of a worldwide genotype collection of six allopolyploid and five diploid wild strawberry (Fragaria) taxa in three climatically different common gardens.Among leaf functional traits, we detected divergence in trait means but not plasticities between polyploids and diploids, suggesting that increased genomic redundancy in polyploids does not necessarily translate into greater trait plasticity in response to environmental change. 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 elucidate essential ecological mechanisms underlying polyploid adaptation to heterogeneous environments, and provide an important insight into the prevalence and persistence of polyploid plants.
Highlights
Polyploidy enlarges and diversifies an organism’s genome, with profound influence on phenotype and fitness (Otto & Whitton 2000; Ramsey & Ramsey 2014; Soltis et al 2016)
By growing clonal replicates of a worldwide collection of Fragaria genotypes of six allopolyploid and five diploid species in three climatically different common gardens in Oregon, USA, we addressed the following questions: (1) Do functional traits differ between diploids and polyploids? (2) Do polyploids demonstrate higher trait plasticity than diploids in response to environmental change? (3) Is there a polyploid fitness advantage across diverse garden environments? (4) If so, is the polyploid fitness advantage conferred by trait means, trait plasticities, or both? Our results indicate that polyploids and diploids differ in several leaf functional traits
Diploid and polyploid Fragaria differed in most leaf functional traits (Fig. 2; Table S3), either consistently across environments or in certain environments (e.g. SLA, stomatal density and nitrogen content)
Summary
Polyploidy (or whole-genome duplication) enlarges and diversifies an organism’s genome, with profound influence on phenotype and fitness (Otto & Whitton 2000; Ramsey & Ramsey 2014; Soltis et al 2016). A leading, yet rarely tested, hypothesis is that polyploid fitness advantage arises from enhanced means in functional traits and/or the ability to adjust phenotype (i.e. trait plasticity) in response to environmental change (Levin 1983; Van de Peer et al 2017). Polyploidy can alter plant phenotype (Levin 1983; Soltis et al 2014). Phenotypic variation at the cellular level (e.g. an increase in cell size) as a result of an increase in ploidy was first recognized in early cytological studies of synthetic polyploids
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