Phenotypic Plasticity in Sympatric Diploid and Autotetraploid Dactylis glomerata

It is often supposed that increased heterozygosity of autopolyploids provides a greater stability of phenotypic expression compared with related diploids and, hence, a greater ability to survive in marginal diploid environments or the ability to colonize new environments. The aim of this study was to compare the phenotypic plasticity of fitness‐related characters in diploid and derivative autotetraploid Dactylis glomerata from genotypes sampled in their zone of natural sympatric occurrence in northern Spain. To achieve this aim, nine genotypes were grown in a range of controlled environments. We found no evidence for consistent differences in plasticity between diploids and related tetraploids. We did find, however, consistent differences between diploids and tetraploids in the mean values of the set of examined fitness‐related characters. Such differences could be critical for the maintenance and evolutionary success of polyploids.