Recent theoretical studies have shown that mixed reproductive systems in angiosperms can be stable, but empirical data to confirm this hypothesis are still scarce. Arista et al. study four populations of Hypochaeris salzmanniana (Asteraceae) during two consecutive years.
They find that self-compatibility increases when the pollination environment is uncertain, conferring reproductive assurance when pollinator attendance is low. The mixed reproductive system of H. salzmanniana appears to be an evolutionarily stable strategy, with year-to-year changes in self-incompatibility expression deriving directly from the balance between reproductive assurance and inbreeding depression.
Arista, M., Berjano, R., Viruel, J., Ortiz, M. Á., Talavera, M., & Ortiz, P. L. (2017). Uncertain pollination environment promotes the evolution of a stable mixed reproductive system in the self-incompatible Hypochaeris salzmanniana (Asteraceae). Annals of Botany, 120(3), 447–456. https://doi.org/10.1093/aob/mcx059