Conspicuous, green flowers are an honest signal of nectar rewards in a bird-pollinated tree (Fuchsia excorticata, Onagraceae)

IF 1.9 4区环境科学与生态学 Q3 ECOLOGY Plant Ecology Pub Date : 2024-02-02 DOI:10.1007/s11258-023-01390-6

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Abstract

Bird-pollinated flowers typically appear ‘red’. Fuchsia excorticata (Onagraceae), a gynodioecious tree species endemic to New Zealand, is a notable exception. It produces ‘green’, cauliflorous flowers at early stages in flower ontogeny, when pistils are receptive. Flowers later turn ‘red’ as they lose their receptivity. We conducted field observations and spectrographic analyses to test whether: (1) receptive, green-phase flowers are actually more conspicuous to avian pollinators against their natural backgrounds than unreceptive, red-phase flowers, (2) green-phase flowers produce more nectar, and (3) relationships between flower conspicuousness and nectar production are similar in females and hermaphrodites. Results showed that the reflectance properties of green-phase flowers sharply contrast ‘orange’ tree bark, their natural visual background, rendering them more conspicuous to the avian eye than red-phase flowers. Green-phase flowers also produced more nectar than red-phase flowers as an honest signal of rewards. Similar results were observed in both female and hermaphrodite plants. Overall results provide an unusual example of reversed flower-background colour contrasts, with ‘reddish’ hues being incorporated into the visual backgrounds of floral displays rather than being associated with the flowers themselves. They also illustrate that flower conspicuousness can serve as an honest signal of nectar rewards to pollinators.

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显眼的绿色花朵是鸟类授粉树（小叶紫薇，Onagraceae）采蜜的诚实信号

摘要鸟类授粉的花朵通常呈现 "红色"。Fuchsia excorticata（Onagraceae）是新西兰特有的雌雄异株树种，是一个明显的例外。它在花朵发育的早期阶段，当雌蕊处于受精状态时，会开出 "绿色 "的茎花。后来，随着雌蕊失去受精能力，花朵会变成 "红色"。我们进行了实地观察和光谱分析，以检验：(1) 与无感受性的红花相比，有感受性的绿色花期花朵在鸟类授粉者的自然背景中是否更显眼；(2) 绿色花期花朵是否能产生更多花蜜；(3) 雌花和雌雄同体花朵的显眼度与花蜜产量之间的关系是否相似。研究结果表明，绿相花的反射特性与其自然视觉背景 "橙色 "树皮形成鲜明对比，使其在鸟类眼中比红相花更显眼。绿色花期的花朵也比红色花期的花朵分泌更多的花蜜，这是一种诚实的奖励信号。在雌株和雌雄同体植物中也观察到了类似的结果。总体结果提供了一个不寻常的例子，说明花朵与背景颜色反向对比，"偏红 "色调被纳入花朵展示的视觉背景中，而不是与花朵本身联系在一起。这些结果还说明，花朵的显眼程度可以作为授粉者获得花蜜奖励的诚实信号。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Plant Ecology 环境科学-林学

CiteScore

3.40

自引率

0.00%

发文量

审稿时长

8.6 months

期刊介绍： Plant Ecology publishes original scientific papers that report and interpret the findings of pure and applied research into the ecology of vascular plants in terrestrial and wetland ecosystems. Empirical, experimental, theoretical and review papers reporting on ecophysiology, population, community, ecosystem, landscape, molecular and historical ecology are within the scope of the journal.