Separated Sexes, Shared Consequences: Disentangling Predictors of Genetic Diversity in Dioecious Angiosperms

ABSTRACT Sexual systems such as dioecy, although rare in angiosperms, seem to enhance intrapopulation genetic diversity due to obligate outcrossing. Empirical studies had strengthened theoretical predictions that genetic diversity in dioecious angiosperms is strongly linked to population demographic structure, phenological patterns, and species life‐history traits such as pollination mode and seed dispersal syndrome. As anthropogenic pressures and climate change have disrupted and altered plant reproduction, understanding how ecological and environmental factors modulate genetic diversity in threatened dioecious angiosperms is paramount to inform and to establish effective conservation and management plans. Here, we compiled genetic and ecological data of 66 dioecious angiosperms from articles published until August 2025. To test the effects of pollination mode, seed dispersal syndrome, reproductive mode, growth form, conservation status, endemism, and species distribution range on intrapopulation genetic diversity (i.e., H E ), we implemented Generalized Linear Mixed Models fitted with Template Model Builder. Our results revealed that species conservation status and endemism play a significant role in the patterns of H E among dioecious angiosperms, with endemic and/or threatened species showing reduced levels of genetic diversity. Pollination mode also emerged as an important predictor of H E , with abiotically pollinated species exhibiting highest genetic diversity. Pruning not only the knowledge on how ecological and evolutionary processes drive molecular variation in dioecious angiosperms, our study is also an attempt to strengthen conservation efforts to plant species presenting rare sexual system. We stress that dioecious angiosperms should be targeted as priority in conservation agendas worldwide.