Waelti Marc O, Page Paul A, Widmer Alex, Schiestl Florian P
Plant Ecological Genetics, Institute of Systematic Botany, ETH Zürich, Zürich, Switzerland.
BMC Evol Biol. 2009 Aug 6;9:190. doi: 10.1186/1471-2148-9-190.
Sexual selection theory predicts that males are limited in their reproductive success by access to mates, whereas females are more limited by resources. In animal-pollinated plants, attraction of pollinators and successful pollination is crucial for reproductive success. In dioecious plant species, males should thus be selected to increase their attractiveness to pollinators by investing more than females in floral traits that enhance pollinator visitation. We tested the prediction of higher attractiveness of male flowers in the dioecious, moth-pollinated herb Silene latifolia, by investigating floral signals (floral display and fragrance) and conducting behavioral experiments with the pollinator-moth, Hadena bicruris.
As found in previous studies, male plants produced more but smaller flowers. Male flowers, however, emitted significantly larger amounts of scent than female flowers, especially of the pollinator-attracting compounds. In behavioral tests we showed that naïve pollinator-moths preferred male over female flowers, but this preference was only significant for male moths.
Our data suggest the evolution of dimorphic floral signals is shaped by sexual selection and pollinator preferences, causing sexual conflict in both plants and pollinators.
性选择理论预测，雄性的繁殖成功率受获得配偶机会的限制，而雌性则更多地受资源限制。在动物传粉的植物中，吸引传粉者和成功授粉对繁殖成功至关重要。因此，在雌雄异株的植物物种中，雄性应通过在增强传粉者访花的花部性状上比雌性投入更多，来提高自身对传粉者的吸引力。我们通过研究花部信号（花展示和香味）并对传粉者——双斑希夜蛾进行行为实验，来检验雌雄异株、蛾类传粉的草本植物宽叶蝇子草中雄花具有更高吸引力这一预测。
如先前研究发现，雄株产生的花更多但更小。然而，雄花释放的气味量显著大于雌花，尤其是吸引传粉者的化合物。在行为测试中我们发现，未接触过的传粉者——蛾子更喜欢雄花而非雌花，但这种偏好仅对雄蛾显著。
我们的数据表明，两性异形花部信号的进化受性选择和传粉者偏好影响，在植物和传粉者中都引发了性冲突。
