Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT, Australia.
Kings Park and Botanic Garden, The Botanic Garden and Parks Authority, West Perth, WA, Australia.
J Evol Biol. 2018 Nov;31(11):1732-1742. doi: 10.1111/jeb.13370. Epub 2018 Oct 8.
Pollination by sexual deception of male insects is perhaps one of the most remarkable cases of mimicry in the plant kingdom. However, understanding the influence of floral traits on pollinator behaviour in sexually deceptive plants is challenging, due to the risk of confounding changes in floral odour when manipulating morphology. Here, we investigated the floral traits influencing the sexual response of male Zaspilothynnus nigripes (Tiphiidae) wasps, a pollinator of two distantly related sexually deceptive orchids with contrasting floral architecture, Caladenia pectinata and Drakaea livida. In D. livida, the chemical sexual attractant is emitted from the labellum, whereas in C. pectinata, it is produced from the distal sepal tips, allowing manipulative experiments. When controlling for visual cues, there was no difference in long-distance attraction, although the floral odour of D. livida induced copulation more frequently than that of C. pectinata. The role of colour in pollinator sexual attraction was equivocal, indicating that colour may not be a strong constraint on the initial evolution of sexual deception. The frequency of wasp visitors landing on C. pectinata decreased when the amount of floral odour was reduced, but attempted copulation rates were enhanced when the source of floral odour was associated with the labellum. These latter variables may represent axes of selection that operate across many sexually deceptive species. Nonetheless, the observed variation in floral traits suggests flexibility among species in how sexual deception can be achieved.
昆虫的有性欺骗授粉也许是植物界中最显著的拟态案例之一。然而，由于在操纵形态时花朵气味可能会发生混淆，因此理解花朵特征对有性欺骗植物传粉者行为的影响具有挑战性。在这里，我们研究了影响雄性 Zaspilothynnus nigripes（Tiphiidae 科）黄蜂有性反应的花朵特征，这种黄蜂是两种具有不同花部结构的有性欺骗兰花（Caladenia pectinata 和 Drakaea livida）的传粉者。在 D. livida 中，化学性引诱剂从唇瓣发出，而在 C. pectinata 中，它从远端萼片尖端产生，从而可以进行操纵实验。在控制视觉线索的情况下，远距离吸引力没有差异，尽管 D. livida 的花朵气味比 C. pectinata 更频繁地诱导交尾。颜色在传粉者性吸引中的作用是不确定的，这表明颜色可能不是性欺骗最初进化的一个强有力的限制因素。当减少花朵气味的量时，落在 C. pectinata 上的黄蜂访客的频率下降，但当花朵气味的来源与唇瓣相关时，试图交尾的比率增加。这些后一个变量可能代表了在许多有性欺骗物种中起作用的选择轴。尽管如此，观察到的花朵特征的变化表明，在实现有性欺骗方面，物种之间存在灵活性。
