Data from: Looks matter: changes in flower form affect pollination effectiveness in a sexually-deceptive orchid

Many species of the sexually-deceptive genus Ophrys are characterized by insect-like flowers. Their form has been traditionally considered to play an important role in pollinator attraction and manipulation. Yet the evolution of the floral form remains insufficiently understood. We hypothesize that pollinator-mediated selection is essential for driving floral form evolution in Ophrys, but that form components are being subjected to varying selection pressures depending on their role in mediating interactions with pollinators. By using the Eucera pollinated Ophrys leochroma as a model, our aim has been to assess whether and in what manner pollination effectiveness is altered by experimental manipulation of the flower form. Our results show that the floral form plays an essential and, so far, underestimated role in ensuring effective pollination by mechanically guiding pollinators towards the reproductive structures of the flower. Pollinators are significantly less effective in interacting with flowers having forms altered to resemble those of species pollinated by different hymenopteran genera. Further, those components used by pollinators as gripping points were found to be more effective in ensuring pollinia transfer than those with which pollinators do not directly interact. Thus, mechanically-active and –inactive components appear to be under different selection pressures. As a consequence, mechanically-active components of the flower form could reflect adaptations to the interaction with particular pollinator groups, while inactive components can vary more freely. Disentangling selection patterns between the functionally different components of flower form may provide valuable insights into the mechanisms driving the morphological diversification of sexually-deceptive pollination-systems.

性欺骗类眉兰属（Ophrys）的诸多物种，以具昆虫形态的花朵为典型特征。长期以来，学界普遍认为其花部形态在吸引、操控传粉者（pollinator）方面发挥着关键作用。然而，学界对其花部形态的演化机制仍缺乏充分认知。本研究提出假说：传粉介导的选择是驱动眉兰属花部形态演化的核心要素，但花部各组成部分因在介导与传粉者的互作中发挥的功能不同，所承受的选择压力也存在差异。本研究以受地蜂属（Eucera）传粉的眉兰物种Ophrys leochroma为模式材料，旨在探究通过实验操控花部形态是否会改变传粉效率，以及具体的影响路径。研究结果表明，花部形态在通过机械引导传粉者抵达花朵生殖结构以保障高效传粉方面，发挥着此前被学界低估的关键作用。当花部形态被改造为与其他由不同膜翅目（Hymenoptera）昆虫属类传粉的物种相似时，传粉者与花朵的互作效率会显著降低。此外，传粉者用作抓附位点的花部组成部分，相较于传粉者未直接接触的部分，在保障花粉块（pollinia）传递方面效率更高。由此可见，具有机械活性与无机械活性的花部组成部分，所承受的选择压力存在显著差异。因此，花部形态中具有机械活性的组成部分，可反映出对特定传粉者类群互作的适应性演化，而无机械活性的组成部分则可更自由地发生变异。厘清花部形态不同功能组成部分间的选择模式，可为揭示性欺骗传粉系统的形态多样性演化机制提供极具价值的研究视角。