Premise—Although polyploidy has been studied since the early 1900’s, fundamental aspects of polyploid ecology and evolution remain unexplored. In particular, surprisingly little is known about how newly formed polyploids (neopolyploids) become demographically established. Models predict that most polyploids should go extinct within the first few generations due to reproductive disadvantages associated with being the minority in a primarily diploid population (i.e., the minority cytotype principle), yet polyploidy is extremely common. Therefore, a key goal in the study of polyploidy is to determine the mechanisms that promote polyploid establishment in nature. Because premating isolation will be critical for neopolylpoids to avoid minority cytotype exclusion and thus facilitate establishment, we examined floral morphology and three common premating barriers to determine their importance in generating reproductive isolation of neopolyploids from diploids.

Methods—We induced neopolyploidy in Trifolium pratense and compared their floral traits to the diploid progenitors. In addition to shifts in floral morphology, three premating barriers were examined: isolation by self-fertilization, flowering time asynchrony, and pollinator mediated isolation.

Results—We found significant differences in the morphology of diploid and neopolyploid flowers, but these changes did not facilitate premating barriers that would generate reproductive isolation of neopolyploids from diploids. There was no difference in flowering phenology, pollinator visitation, or selfing between the cytotypes.

Conclusions—Our results indicate that barriers other than the ones tested in this study, such as geographic isolation, vegetative reproduction, or pistil-stigma incompatibilities, might be more important in facilitating isolation and establishment of neopolyploid Trifolium pratense.

Data was collected in the field, and entered in spreadsheets at a later date.