“…Although present in only 5â6% of angiosperm species (Renner and Ricklefs, ; Charlesworth, ), the evolution of separate sexes is a recurring transition in angiosperms (Geber et al., ; Charlesworth, ; Renner, ). The occurrence of two mating types in populations, for example, females and males in dioecious populations or females and hermaphrodites in gynodioecious populations, has direct effects on patterns of mating as well as important emergent consequences such as the evolution of sexual dimorphism (Barrett and Hough, ; Kamath et al., ) and sex ratio evolution (McCauley and Taylor, ; Van Etten and Chang, ; Rivkin et al., ). A common pathway to separate sexes is the origin and spread of maleâsterility in otherwise hermaphroditic populations (i.e., gynodioecy; Webb, ; Spigler and Ashman, ).…”