Dark purple nectar as a foraging signal in a bird‐pollinated Himalayan plant

Zhang, Fengping; Cai, Xiang‐Hai; Hong, Wang; Ren, Zong‐Xin; Larson‐Rabin, Zachary; D, Li

doi:10.1111/j.1469-8137.2011.03894.x

Cited by 30 publications

(37 citation statements)

References 26 publications

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“…Geckos were more attracted to the darkest artificial nectar, suggesting that they perceived darker artificial nectar as offering a greater reward than lighter artificial nectar. Signal strength may be enhanced by either larger drops being formed on the plant's corolla, as a result of the nectar volume increasing when the nectar remains uneaten, or by nectar colour changes that occur over time, perhaps due to oxidation (Hansen et al 2007a;Zhang et al 2012), or evaporation (Nicolson & Nepi 2005Zhang et al 2012), which may indicate a higher reward as the sugar concentration increases. To the pollinator, this means that fewer flowers must be visited to acquire the same amount of energy, thereby reducing the cost of searching for food.…”

Section: Discussionmentioning

confidence: 99%

“…Birds have been shown experimentally to prefer coloured nectar to clear nectar (Collias & Collias 1968;Johnson et al 2006;Zhang et al 2012). This is most likely due to the signal strength of coloured nectar (Johnson et al 2006;Hansen et al 2007a;Zhang et al 2012) and the birds' visual capacities ).Coloured nectar is often associated with secondary metabolites, such as non-protein amino acids, phenolic compounds or alkaloids, and in fact, these substances may be the cause of the colour (Hansen et al 2007a). The nectar of the suspected gecko-visited N. mauritianus contains aurones, products of flavonoid biosynthesis (Olesen et al 1998).…”

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confidence: 99%

“…at 10h00), and we terminated them when a gecko's consumption had lowered the artificial nectar level to the 1 ml mark on the Eppendorf® tube (the level that its tongue could still comfortably reach) or after 6 h. Geckos were given their maintenance diet for one day between trials, then starved for one day before test days (to ensure that geckos fed from the test solution). Each of the seven geckos received all colour pairs, the order of which was randomly determined.Earlier studies have used first choice as an index of colour preference (Hansen et al 2006;Schaefer et al 2006;Zhang et al 2012). In addition to first choice, we recorded food intake, visitation frequency and visitation length to compare these feeding parameters as indices of colour preference.…”

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Coloured and Toxic Nectar: Feeding Choices of the Madagascar Giant Day Gecko, Phelsuma grandis

et al. 2013

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Coloured nectar is a rare phenomenon best known from islands and insular habitats. Islands are also known for lizard pollination, where coloured nectar potentially acts as a visual cue to attract pollinators, advertising the sweet reward. However, nectar may also contain secondary metabolites with toxic or deterrent effects. The aim of this study was to determine which factors are important as artificial nectar choice determinants to the Madagascar giant day gecko, Phelsuma grandis, an island pollinator: artificial nectar colour, artificial nectar colour saturation, artificial nectar conspicuousness and/or the presence of the alkaloid nicotine. Coloured artificial nectar and the darkest artificial nectar colour saturation were found to be important visual cues for the geckos, while the contrast between artificial nectar and petal colour was not. Geckos were deterred only by high nicotine concentrations (1000 lM in 0.63 M sucrose) and may even prefer low nicotine concentrations to sucrose-only solutions. Given their overall fondness for sugar solutions, Madagascar giant day geckos are likely to be important pollinators of Malagasy plant species that produce enough nectar to attract them, and plants with coloured nectar and/or secondary metabolites may have evolved those traits to attract the geckos in particular.The role of lizards as seed dispersers and pollinators is relatively unknown among animal-plant interactions. Most reports of nectar consumption by lizards are from islands. Lizards may reach relatively high densities on islands as a result of low predation levels, and insect pollinators are often scarce on islands (reviewed in Olesen & Valido 2003). Consequently, it has been suggested that insectivorous lizards have expanded their diets to include fruit and nectar; this niche broadening has led to their playing unusual roles as pollinators and seed dispersers (Eifler 1995;Traveset & Saez 1997;Olesen & Valido 2003;Kaiser-Bunbury et al. 2009).Another feature of plant-animal interactions on islands is the presence of coloured nectar (Hansen et al. 2007a). Although the information is insufficient, this floral trait appears to be more common in circumstances where invertebrate pollination is limited, such as insularity, high altitudes and where vertebrate pollinators are abundant; these correlates are not necessarily mutually exclusive (Hansen et al. 2007a). In addition to being a visual cue to vertebrate pollinators, it has been suggested that coloured nectar acts as an honest signal, where the flower advertises the strength and presence of its reward: the more saturated the colour of the nectar (i.e. the darker it is) the stronger the signal (Olesen et al. 1998;Johnson et al. 2006;Hansen et al. 2007a).A large variety of nectar colours has been found to occur in nature (Hansen et al. 2007a). Plants that are known or suspected to be pollinated by lizards (Trochetia boutoniana, T. blackburniana and Nesocodon mauritianus) have (human-perceived) coloured nectar in the clear to red range and bell-shaped ...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Coloured and Toxic Nectar: Feeding Choices of the Madagascar Giant Day Gecko, Phelsuma grandis

et al. 2013

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“…Plants growing in insular habitats, such as islands and mountain ranges, may be extremely pollinator limited if they are self-incompatible or need pollinators to increase pollination efficiency (51,52). In two recently documented cases, the coupling of signal and reward through colored nectar allowed the pollinator to assess nectar availability before flower visitation, increasing their efficiency as foragers and pollinators (53,54).…”

Section: Ultimate Mechanisms: Honest Signaling Effects On Plant-pollimentioning

confidence: 99%

Floral humidity as a reliable sensory cue for profitability assessment by nectar-foraging hawkmoths

Arx

Goyret

Davidowitz

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

110

148

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Most research on plant-pollinator communication has focused on sensory and behavioral responses to relatively static cues. Floral rewards such as nectar, however, are dynamic, and foraging animals will increase their energetic profit if they can make use of floral cues that more accurately indicate nectar availability. Here we document such a cue-transient humidity gradients-using the night blooming flowers of Oenothera cespitosa (Onagraceae). The headspace of newly opened flowers reaches levels of about 4% above ambient relative humidity due to additive evapotranspirational water loss through petals and water-saturated air from the nectar tube. Floral humidity plumes differ from ambient levels only during the first 30 min after anthesis (before nectar is depleted in wild populations), whereas other floral traits (scent, shape, and color) persist for 12-24 h. Manipulative experiments indicated that floral humidity gradients are mechanistically linked to nectar volume and therefore contain information about energy rewards to floral visitors. Behavioral assays with Hyles lineata (Sphingidae) and artificial flowers with appropriate humidity gradients suggest that these hawkmoth pollinators distinguish between subtle differences in relative humidity when other floral cues are held constant. Moths consistently approached and probed flowers with elevated humidity over those with ambient humidity levels. Because floral humidity gradients are largely produced by the evaporation of nectar itself, they represent condition-informative cues that facilitate remote sensing of floral profitability by discriminating foragers. In a xeric environment, this level of honest communication should be adaptive when plant reproductive success is pollinator limited, due to intense competition for the attention of a specialized pollinator.pollination biology | honest signaling | floral display P lant-pollinator relationships-like all mutualisms-strike a tenuous balance between the conflicting interests of foraging animals and flowering plants (1, 2). For flowering plants, pollinator attraction through floral density, form, color, pattern, and odor is necessary but insufficient to ensure effective pollination. Ideally, pollinators should transfer pollen between conspecific plants in ways that result in favorable levels of outcrossing (3) and reduced pollen loss (4). Flowers commonly manipulate pollinator movement by varying quality or quantity of floral nectar. The offer of variable amounts of nectar (5, 6), toxic nectar (7, 8), or an empty promise of nectar elicit similar results: pollinators leave plants sooner, reducing for example geitonogamous inbreeding (if selfcompatible) or pollen discounting (if self-incompatible).The availability of floral rewards often coincides with floral display and pollinator activity on a gross temporal scale (i.e., hours) (9, 10). Nevertheless, most pollinators encounter rewardless ("empty") flowers on a finer temporal scale (i.e., minutes), often due to recent visitation by another animal. From the pollin...

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Secondary Metabolites: Attracting Pollinators

Sosenski

Parra‐Tabla

2019

Encyclopedia of Life Sciences

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Flowers present visual and chemical signals that mediate the interaction between plants and pollinators, who transfer pollen between flowers of different plants while foraging for nectar and/or pollen. This process favours the sexual reproduction of plants and covers the energy requirements of floral visitors. Colour and floral scent, as well as the chemical composition of nectar and pollen that constitute floral rewards, are among the attraction attributes. The expression of these attributes is the result of the production of a set of secondary metabolites such as pigments, volatile organic compounds and chemical compounds in nectar and pollen. In addition to attracting pollinators, these metabolites can repel natural enemies of plants (florivores, nectar robbers, microorganisms) or pollinators (pathogens), potentially affecting the outcome of pollination, and eventually the production of fruits and seeds. Key Concepts Most flowering plants that depend on pollinators for reproducing sexually have developed visual (colour) and chemical (scent) floral signals, as well as floral rewards (pollen and nectar), to increase the attraction of pollinators. Secondary metabolites produced by flowering plants mediate the visual and chemical communication between plants and other organisms. While this communication is essential for pollination, it can also mediate the interaction of plants with florivores, nectar robbers, seed predators, microorganisms and pollinator pathogens that could affect pollination. Pollinators are able to perceive variation in visual and chemical attributes of plants from the same or different species, affecting visitation rates and plant fitness. Pigments are the secondary metabolites responsible for the synthesis of colour in different floral organs (petals, sepals, sexual organs) and floral rewards (pollen and nectar). Floral volatiles are organic compounds emitted by flowers that mediate chemical communication in specialist and generalist plant–pollinators interactions. Secondary metabolites in the nectar of various species include alkaloids, phenols and nonessential amino acids that can affect the preferences and foraging behaviour of pollinators, either by attracting or deterring them. The impact of secondary metabolites in attracting different pollinators can result in pre‐reproductive isolation between plants and eventually contribute to their divergence.

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Dark purple nectar as a foraging signal in a bird‐pollinated Himalayan plant

Cited by 30 publications

References 26 publications

Coloured and Toxic Nectar: Feeding Choices of the Madagascar Giant Day Gecko, Phelsuma grandis

Coloured and Toxic Nectar: Feeding Choices of the Madagascar Giant Day Gecko, Phelsuma grandis

Floral humidity as a reliable sensory cue for profitability assessment by nectar-foraging hawkmoths

Secondary Metabolites: Attracting Pollinators

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