Polyploidy has important effects on plant reproductive systems and previously has been implicated in the evolution of dimorphic reproductive strategies.
Miller et al. use flow cytometry, observations of pollen production, and morphological measurements to document the perfect association of tetraploidy with gender dimorphism (or diploidy with cosexuality) across 36 populations spanning the geographic range. Molecular sequence data strongly confirm the monophyly of Lycium californicum, and character mapping suggests that tetraploid-dimorphic populations have arisen twice independently and in concert. Interestingly, the distribution of tetraploid-dimorphic populations is restricted to populations in Arizona and the Baja California peninsula, and may be associated with harsh environmental conditions