Data from: Sexually antagonistic evolution caused by male-male competition in the pistil

While sexual selection and sexual conflict are important evolutionary forces in animals, their significance in plants is uncertain. In hermaphroditic organisms, such as many plants, sexual conflict may occur both between mating partners (inter-locus conflict) and between male and female sex roles within an individual (intra-locus conflict). We performed experimental evolution, involving lines that were crossed with either one or two pollen donors (monogamous or polyandrous lines), in the hermaphroditic plant (<i>Collinsia heterophylla</i>) where early fertilizations are associated with female fitness costs (reduced seed set). Artificial polyandry for four generations resulted in enhanced pollen performance and increased female fitness costs compared to the monogamous and source (starting material) lines. Female fitness was also reduced in the monogamous line, indicating a possible trade-off between sex roles, resulting from early pollination. We performed a second experiment to investigate a potential harming effect of pollen performance on seed set. We found that high siring success of early-arriving pollen competing with later-arriving pollen was associated with high female fitness costs, consistent with an inter-locus sexual conflict. Our study provides evidence for the importance of sexual selection in shaping evolution of plant reproductive strategies, but also pinpoints the complexity of sexual conflict in hermaphroditic species.

尽管性选择与性冲突是动物界重要的进化动力，但其在植物中的研究意义仍未明确。对于多数植物这类雌雄同体生物而言，性冲突既可能出现于交配伴侣之间（基因座间冲突，inter-locus conflict），也可能存在于个体内部的雄性与雌性生殖功能之间（基因座内冲突，intra-locus conflict）。我们以雌雄同体植物<i>Collinsia heterophylla</i>为研究对象开展了实验进化研究，该物种的早期受精事件会伴随雌性适合度成本（结实率降低）。实验中我们将实验株系分别与1个或2个花粉供体进行杂交，构建单配系与多配系。经过四代人工多配处理后，相较于单配系及原始起始株系，多配系的花粉活力显著提升，但雌性适合度成本也随之升高。单配系的雌性适合度同样出现下降，这表明早期授粉可能引发了生殖功能间的权衡效应。我们开展了第二项实验，以探究花粉活力对结实率的潜在伤害效应。研究发现，与晚到花粉竞争时，早到花粉的高父本成功率会伴随较高的雌性适合度成本，这与基因座间性冲突的理论预期一致。本研究证实了性选择在塑造植物生殖策略演化过程中的重要性，同时也揭示了雌雄同体物种中性冲突的复杂性。