Male-biased sexual selection persists across contrasting habitats in a dioecious plant

Abstract In most angiosperms, pollinators mediate access to sexual partners, making attractive floral traits key targets of sexual selection. Theory predicts stronger selection through the male function, due to greater dependence of male reproductive success on mate acquisition. However, habitat degradation may alter plant–pollinator interactions and disrupt sex-specific selection. In particular, reduced pollinator density may increase the dependency of female reproductive success on mate acquisition and strengthen selection on floral traits in both sexes. We tested this hypothesis in the dioecious species Silene dioica by measuring pollinator visitation, pollination service, and phenotypic selection on floral traits in both sexes across six populations located in either forest or anthropogenic habitats. Despite lower visitation in anthropogenic sites, pollination service was comparable between habitats with consistent selection on fertility-related traits in females. In contrast, we found stronger selection on a male trait likely promoting efficient pollen transfer in anthropogenic habitats, indicating a sex-specific response to land use change. Finally, male—but not female—reproductive success increased with the number of sexual partners in both habitats, supporting stronger sexual selection in males. More broadly, our results emphasize the need for a sex-specific perspective on floral trait evolution and demonstrate the persistence of male-biased sexual selection under environmental change.