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.

性欺骗型兰属（Ophrys）的诸多物种以具昆虫状花朵为典型特征。长期以来，学界普遍认为其花部形态在传粉者吸引与操控过程中发挥着关键作用，但目前学界对该属植物花部形态的演化机制仍缺乏充分认知。本研究提出假说：传粉者介导的选择是驱动眉兰属花部形态演化的核心要素，而花部形态的不同组分因在介导与传粉者互作中的功能差异，会受到不同选择压力的作用。本研究以由长须蜂属（Eucera）传粉的褐毛眉兰（Ophrys leochroma）为模式物种，旨在探究花部形态的实验操控是否会改变传粉有效性，以及具体的作用方式。研究结果表明，花部形态通过机械引导传粉者接触花朵的生殖结构，在保障高效传粉方面发挥着此前被低估的关键作用。当花朵形态被改造为与其他由不同膜翅目昆虫属传粉的物种相似时，传粉者的传粉效率会显著降低。此外，传粉者用作抓附位点的花部组分，相比传粉者未直接接触的组分，能更有效地实现花粉块传递。由此可见，具有机械活性与无机械活性的花部组分，所处的选择压力存在显著差异。据此推测，花部形态中具有机械活性的组分，可反映其对特定传粉者类群互作的适应性演化，而无机械活性的组分则可发生更为自由的变异。厘清花部形态不同功能组分间的选择模式差异，可为揭示驱动性欺骗传粉系统形态多样化的内在机制提供极具价值的研究视角。