Data from: Do sun orchids mimic buzz-pollinated plants? An experimental test of the adaptive significance of false anthers

Mimicry implies that an organism gains fitness by resembling a model
species, and one example is rewardless plants that attract pollinators by
resembling co-flowering species that provide rewards. While trait matching
between mimic and model has been characterised in many cases of putative
floral mimicry, few have demonstrated that resemblance is adaptive and
dependent on model presence.  Sun orchids (Thelymitra) are
believed to mimic flowers of buzz-pollinated rewarding plants by
displaying false anthers. To test the adaptive value of the false anthers
we examined whether fruit production of T. crinita and T. macrophylla was
reduced when anthers were experimentally removed or obscured, and whether
the reduction was stronger when putative model plants were abundant. We
also assessed visual flower similarity of both orchids and their putative
model plants according to bee colour perception and identified shared
pollinators and whether their behaviour on T. crinita was similar to that
on buzz-pollinated model plants.  Fruit production of both sun
orchids was strongly reduced (60-71%) by removal or painting of false
anthers but was not affected by the abundance of model plants. Sun orchid
flowers closely matched flower colour of co-flowering pollen-rewarding
species, and T. crinita shared pollinators with the rewarding species.
Visiting bees attempted to buzz and manipulate the false anther, with a
behaviour similar to that observed on model plants.  The
experimental results demonstrate that the false anther is an important
adaptation to pollination in sun orchids. Striking visual flower
similarity and shared pollinators between orchids and models suggest that
sun orchids are pollinated by bees that mistake orchids for
buzz-pollinated rewarding plants. The adaptive value of the false anther
did not depend on model plant abundance in the local population,
indicating that the relevant spatial scale is larger, or that the effects
of the model species are weak in comparison to effects of other rewarding
species, i.e., that magnet effects of nectar-rewarding species are
dominating.  False anthers are widespread in the genus
Thelymitra, and this “mimicry trait” seems to represent an evolutionary
novelty that offers unique opportunities to explore adaptations to
pollination in deceptive plants.

拟态（Mimicry）指生物体通过模拟模型物种以获得适合度的演化策略，典型案例为无奖励植物通过模仿同期开花的有奖励物种，来吸引传粉者。尽管在诸多推测性花部拟态案例中，拟态者与模型物种间的性状匹配已被广泛刻画，但鲜有研究证实这种相似性具有适应性，且依赖于模型物种的存在。
太阳兰属（Thelymitra）植物被认为通过展示假花药，模拟具备振粉传粉（buzz-pollinated）特性的有奖励植物的花朵。为验证假花药的适应性价值，本研究开展了两项实验：其一，检测当假花药被人工移除或遮蔽时，长毛太阳兰（T. crinita）与大叶太阳兰（T. macrophylla）的座果率是否会下降；其二，检验当推测的模型植物丰富度提升时，座果率的下降幅度是否会进一步增大。此外，本研究还依据蜜蜂的色觉特征，评估了两种太阳兰与其推测模型植物的花部视觉相似度，鉴定了二者共享的传粉者，并观察了蜜蜂在长毛太阳兰上的行为是否与在振粉传粉模型植物上的行为一致。
实验结果显示，移除或涂覆遮蔽假花药会使两种太阳兰的座果率显著降低（降幅达60%~71%），但座果率不受模型植物丰富度的影响。太阳兰的花朵与同期开花的花粉奖励型物种的花色高度匹配，且长毛太阳兰与这些有奖励物种共享传粉者。造访的蜜蜂会尝试振粉并操控假花药，其行为与在模型植物上观察到的行为高度相似。
本实验证实，假花药是太阳兰属植物传粉适应的关键性状。太阳兰与模型植物间显著的花部视觉相似度以及共享的传粉者，表明太阳兰是通过让蜜蜂将其误认作振粉传粉的有奖励植物，从而实现传粉的。假花药的适应性价值不受局域种群中模型植物丰富度的影响，这说明相关的空间尺度更大，或是相较于其他有奖励物种的效应，模型物种的作用较弱——即花蜜奖励型物种的磁效应（magnet effects）占据主导地位。
假花药在太阳兰属中广泛分布，这一“拟态性状”似乎代表了一种演化创新，为探究欺骗性植物（deceptive plants）的传粉适应机制提供了独特的研究契机。