▪ Abstract Polyploidy is widely acknowledged as a major mechanism of adaptation and
speciation in plants. The stages in polyploid evolution include frequent fertility bottlenecks
and infrequent events such as gametic nonreduction and interspecific hybridization, yet little
is known about how these and other factors influence overall rates of polyploid formation.
Here we review the literature regarding polyploid origins, and quantify parameter values for
each of the steps involved in the principal pathways. In contrast to the common claim that …