The signaling function of an extra-floral display: what selects for signal development? (original) (raw)
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Functional significance of the optical properties of flowers for visual signalling
Annals of botany, 2018
Flower coloration is a key enabler for pollinator attraction. Floral visual signals comprise several components that are generated by specific anatomical structures and pigmentation, and often have different functions in pollinator attraction. Anatomical studies have advanced our understanding of the optical properties of flowers, and evidence from behavioural experiments has elucidated the biological relevance of different components of floral visual signals, but these two lines of research are often considered independently. Here, we review current knowledge about different aspects of the floral visual signals, their anatomical and optical properties, and their functional significance in plant-pollinator visual signalling. We discuss common aspects, such as chromatic and achromatic contrast, hue, saturation and brightness, as well as less common types of visual signals, including gloss, fluorescence, polarization and iridescence in the context of salience of floral colour signals ...
learning multimodal cue pollen poricidal anther signal interaction Signals used in communication are frequently complex, being composed of multiple signal components that in combination improve information transfer. A variety of morphological parts are typically used to transmit components of any given complex signal. Our understanding of why a given morphological part is used to transmit a given signal component is poor. We hypothesized that the function of a given signal component is improved by its association with its morphological part and that such parts interact functionally to transmit information. In a laboratory study we characterized the function of different floral signal components transmitted by associated floral parts and the interaction of those signal components. Using Solanum houstonii flowers, we focused on two major floral parts, corolla and anthers, involved in signalling bumblebee, Bombus impatiens, visitors. We further examined how experience affected the relationship between signal component and floral part. Floral visits involve a stepwise process in which bees approach, land and acquire pollen. We found that the corolla plays the dominant role in eliciting approaches by bees, whether naïve or experienced. Landing is elicited by corolla signals and, to a lesser but additive degree, anther signals. Following experience, anther signals nearly completely dominate corolla signals in eliciting landing. The anthers convey signals mediating pollen acquisition, regardless of the bee's experience level. Our findings suggest there is selection for specific relationships between signal components and morphological parts, which in turn might drive complex signal evolution.
Is the flower fluorescence relevant in biocommunication?
Naturwissenschaften, 2010
Flower fluorescence has been previously proposed as a potential visual signal to attract pollinators. In this work, this point was addressed by quantitatively measuring the fluorescence quantum yield (Φ f ) for flowers of Bellis perennis (white, yellow, pink, and purple), Ornithogalum thyrsoides (petals and ovaries), Limonium sinuatum (white and yellow), Lampranthus productus (yellow), Petunia nyctaginiflora (white), Bougainvillea spectabilis (white and yellow), Antirrhinum majus (white and yellow), Eustoma grandiflorum (white and blue), Citrus aurantium (petals and stigma), and Portulaca grandiflora (yellow). The highest values were obtained for the ovaries of O. thyrsoides (Φ f =0.030) and for Citrus aurantium petals (Φ f = 0.014) and stigma (Φ f = 0.013). Emitted photons as fluorescence were compared with reflected photons. It was concluded that the fluorescence emission is negligible compared to the reflected light, even for the most fluorescent samples, and it may not be considered as an optical signal in biocommunication. The work was complemented with the calculation of quantum catches for each studied flower species to describe the visual sensitization of eye photoreceptors.