Merging theory and mechanism in studies of gynodioecy.
Résumé
In gynodioecious species females and hermaphrodites coexist and the genetics of sex determination is usually nuclear-cytoplasmic. Maintaining nuclear-cytoplasmic gynodioecy requires polymorphism for both the feminizing genes (contained in the mitochondria) and the genes that restore male fertility (contained in the nucleus). This complex polymorphism depends in part on there being negative pleiotropic effects (costs) of the nuclear restorer alleles. We combine information from theoretical studies and studies on the molecular action of restorers in crops to interpret the likely costs of restorer alleles, and suggest how various aspects of the theoretical models could be tested. In doing so we highlight how crops can be used to address evolutionary questions about the maintenance of nuclear-cytoplasmic gynodioecy.