PREMISE OF THE STUDY Divergence in functional traits and adaptive responses to environmental change underlies the ecological advantage of polyploid plants in the wild. While established polyploids may benefit from combined outcomes of genome doubling, hybridization and polyploidy-enabled adaptive evolution, it remains less clear whether genome doubling alone can drive ecological divergence or whether the outcome is genetically variable.METHODS Using synthetic, colchicine-induced, autotetraploid (4x) plants derived from self-pollinated diploid (2x) seeds, and their colchicine-treated but unconverted diploid (2x.nc) full sibs from two diploid wild strawberry taxa (Fragaria vesca ssp. vesca and F. vesca ssp. bracteata), we examined the effects of genome doubling on functional traits, heat stress tolerance and fitness components across taxa and maternal families (i.e. genetic families) within taxa.KEY RESULTS Comparisons between 2x and 2x.nc plants indicated a negligible effect of colchicine treatment on functional traits. Genome doubling increased stomatal length, and decreased stomatal density, specific leaf area and leaf vein density, recapitulating patterns observed in wild polyploid Fragaria. Trichome density, heat stress tolerance and relative growth rate were not significantly affected by genome doubling. Although a reduction in clonal reproduction was observed in response to genome doubling, this effect was strongly genetic family dependent.CONCLUSIONS The results suggest that genome doubling during incipient speciation alone can generate ecological divergence and variation among genetic lineages. This response potentially allows for rapid short-term evolutionary adaptation and fuels genomic diversity and independent origins of polyploidy.