Lankinen Åsa, Hydbom Sofia, Strandh Maria
Deparment of Plant Protection Biology, Swedish University of Agricultural Sciences, S-230 53 Alnarp, Sweden.
Department of Biology, Lund University, S-223 62 Lund, Sweden.
Evolution. 2017 Oct;71(10):2359-2369. doi: 10.1111/evo.13329. Epub 2017 Sep 13.
Although 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 (interlocus conflict) and between male and female sex roles within an individual (intralocus 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 (Collinsia heterophylla) 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 interlocus 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.
虽然性选择和性冲突是动物重要的进化驱动力，但其在植物中的重要性尚不确定。在雌雄同体的生物体中，比如许多植物，性冲突可能在交配伙伴之间（基因座间冲突）以及个体内的雄性和雌性性别角色之间（基因座内冲突）发生。我们在雌雄同体植物（异叶柯林斯草）中进行了实验进化，涉及与一个或两个花粉供体杂交的品系（一夫一妻制或一妻多夫制品系），在这种植物中，早期受精与雌性适合度代价（种子结实率降低）相关。与一夫一妻制和原始（起始材料）品系相比，连续四代进行人工一妻多夫制导致花粉表现增强以及雌性适合度代价增加。一夫一妻制品系中的雌性适合度也降低了，这表明由于早期授粉，性别角色之间可能存在权衡。我们进行了第二项实验，以研究花粉表现对种子结实率的潜在伤害作用。我们发现，早到的花粉与晚到的花粉竞争时的高授精成功率与高雌性适合度代价相关，这与基因座间性冲突一致。我们的研究为性选择在塑造植物繁殖策略进化中的重要性提供了证据，但也指出了雌雄同体物种中性冲突的复杂性。
