ABSTRACT

Background

Floral colour is a primary signal in plant-pollinator interactions. Presumably because bees lack red receptors, bee-pollinated flowers are rarely red. Hypericum (Hypericaceae) is a genus, with yellow flowers and filaments, mainly pollinated by bees. However, one species, H. ascyron exhibits unique red filaments.

Aims

We tested whether the red filaments influence pollinator visitation frequency and colour perception.

Methods

We examined whether H. ascyron require pollinators for seed set and compared insect visitation rates of H. ascyron with those of a sympatric yellow-filamented congener. Colour perception by bees was also estimated.

Results

Pollinator visitation substantially enhanced seed set under natural conditions and flowers of H. ascyron had similar rates of visitation by bees as their yellow-filamented congener. Red filaments per se absorbed ultraviolet light and therefore should not be perceived as a chromatic colour by bees. The chromatic contrasts between filaments and petals as perceived by pollinators was similar between species, whereas achromatic contrasts were higher in H. ascyron.

Conclusions

Pure-red staminal filaments work as well in attracting potential pollinators as the yellow filaments of congeners. Based on our findings, we suggest that the evolution of red filament colour may have been driven by factors other than pollinator attraction.

中文翻译：

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蜜蜂授粉植物红色雄蕊的视觉功能

摘要

背景

花色是植物与传粉者相互作用的主要信号。大概是因为蜜蜂缺乏红色受体，蜜蜂授粉的花很少是红色的。金丝桃属（Hypericaceae）属，开黄色花和花丝，主要由蜜蜂授粉。然而，一种H. ascyron表现出独特的红色细丝。

宗旨

我们测试了红色细丝是否影响传粉者的访问频率和颜色感知。

方法

我们检查了H. ascyron是否需要传粉者来结籽，并将H. ascyron的昆虫访问率与同域黄丝同类物的昆虫访问率进行了比较。还估计了蜜蜂的颜色感知。

结果

传粉者的访问显着增强了自然条件下的结实率，而H. ascyron的花与黄丝同类植物的蜜蜂访问率相似。红色细丝本身吸收紫外线，因此不应该被蜜蜂感知为彩色。传粉者感知到的花丝和花瓣之间的色彩对比在物种之间是相似的，而在H. ascyron中消色差对比更高。

结论

纯红色的雄蕊花丝在吸引潜在传粉者方面与同类植物的黄色花丝一样好。根据我们的发现，我们认为红色花丝颜色的演变可能是由传粉者吸引以外的因素驱动的。