Data from: Does morphology matter? An explicit assessment of floral morphology in sexual deception

Sexually deceptive orchids are renowned for their olfactory mimicry of female insect sex pheromones to lure male pollinators, but the role of floral morphology remains unknown. Here, we reveal compelling new experimental evidence that morphology also matters in sexual deception. Our study exploited two morphologically distinct Chiloglottis orchids that both employ the same semiochemical (chiloglottone 1) to attract their respective primary pollinator. In these experiments, we monitored attempted copulation of pollinators with orchid labella as this likely impacts plant fitness. Reciprocal pollinator choice tests revealed significant reductions in the frequency and duration of attempted copulation when pollinators were presented with alternate orchid species that differ in floral morphology, but nevertheless exhibit identical semiochemicals. Experimentally shortening the labellum also reduced the duration of attempted copulation in one of the species. Pollinators exhibited contrasting orientations during attempted copulation and pollination, which seem to be correlated with fundamental differences in the morphological adaptations for both mechanical fit and female mimicry in these orchids. Our findings confirm the overlooked importance of floral morphology for sexually deceptive orchid pollination and indicate that pollinator behaviour could impose strong selection on specific floral traits.

性欺骗型兰科植物素来以模拟雌性昆虫性信息素的嗅觉特征来吸引雄性传粉者而闻名，但其花部形态的作用仍未明晰。本研究提供了极具说服力的全新实验证据，证明花部形态在性欺骗策略中同样发挥关键作用。本研究选取了两个花部形态存在显著差异的盔唇兰属（Chiloglottis）兰花类群，二者均利用同一种信息化合物（盔唇酮1，chiloglottone 1）来吸引各自的主要传粉者。在本实验中，我们监测了传粉者试图与兰花唇瓣交配的行为，因为该行为大概率会影响植物的适合度。交叉传粉者选择试验结果显示，当传粉者接触到花部形态存在差异但信息化合物完全相同的异种兰花时，其试图交配的频率和持续时长均显著降低。实验性缩短其中一个类群的兰花唇瓣，同样会降低传粉者试图交配的持续时长。传粉者在试图交配与完成传粉时展现出截然不同的姿态，这似乎与这两类兰花在机械适配与雌性拟态两方面的形态适应本质差异存在关联。本研究结果证实了此前被忽视的花部形态对性欺骗型兰科植物传粉的重要性，并表明传粉者行为可能对特定花部性状施加了强烈的选择压力。