Data from: The differential contributions of herkogamy and dichogamy as mechanisms of avoiding self-interference in four self-incompatible Epimedium species

Self-interference is one of the most important selective forces in shaping floral evolution. Herkogamy and dichogamy both can achieve reductions in the extent of self-interference, but they may have different roles in minimizing self-interference in a single species. We used four self-incompatible Epimedium species to explore the roles of herkogamy and dichogamy in avoiding self-interference and to test the hypothesis that herkogamy and dichogamy may be separated and become selected preferentially in the taxa. Two species (E. franchetii and E. mikinorii) expressed strong herkogamy and weak protogyny (adichogamy), whereas another two species (E. sutchuenense and E. leptorrhizum) expressed slight herkogamy and partial protandry. Field investigations indicated that there was no physical self-interference between male function and female function regarding pollen removal and pollen deposition in all species. Self-pollination (autonomous or facilitated) was greater in species with slight herkogamy than in those with strong herkogamy. Artificial pollination treatments revealed that self-pollination could reduce outcrossed female fertility in all species, and we found evidence that self-interference reduced seed set in E. sutchuenense and E. leptorrhizum in the field, but not in E. franchetii and E. mikinorii. These results indicate that well-developed herkogamy is more effective compared with dichogamy in avoiding self-interference in the four species. In genus Epimedium, herkogamy instead of dichogamy should be selected preferentially and evolved as an effective mechanism for avoiding self-interference and might not need to evolve linked with dichogamy.

自交干扰（self-interference）是塑造花部进化的关键选择压力之一。雌雄异位（herkogamy）与雌雄异熟（dichogamy）均可降低自交干扰程度，但二者在单一物种内减轻自交干扰的作用可能存在差异。我们以4种自交不亲和（self-incompatible）的淫羊藿属（Epimedium）物种为研究材料，探究雌雄异位与雌雄异熟在规避自交干扰中的作用，并验证“雌雄异位与雌雄异熟可能相互独立，并在类群中受到优先选择”这一假说。其中2个物种（E. franchetii与E. mikinorii）表现出强雌雄异位与弱雌性先熟（protogyny），即雌雄同熟（adichogamy），另外2个物种（E. sutchuenense与E. leptorrhizum）则表现出弱雌雄异位与部分雄性先熟（protandry）。野外调查结果显示，所有物种的雄性功能与雌性功能在花粉移除（pollen removal）与花粉落置（pollen deposition）过程中均未出现物理性自交干扰。具有弱雌雄异位的物种，其自动自花授粉（autonomous self-pollination）与协助自花授粉发生率显著高于强雌雄异位物种。人工授粉实验表明，自花授粉会降低所有物种的异交雌性育性（outcrossed female fertility）；我们还发现，野外条件下自交干扰会降低E. sutchuenense与E. leptorrhizum的结籽率（seed set），但对E. franchetii与E. mikinorii无显著影响。上述结果表明，在这4个物种中，发育完善的雌雄异位在规避自交干扰方面较雌雄异熟更为有效。在淫羊藿属中，雌雄异位而非雌雄异熟应受到优先选择，并演化成为规避自交干扰的有效机制，且未必需要与雌雄异熟协同演化。