How Much Pigment Should Flowers Have? Flowers With Moderate Pigmentation Have Highest Color Contrast

Kooi, Casper J. van der

doi:10.3389/fevo.2021.731626

Cited by 8 publications

(8 citation statements)

References 48 publications

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“…In this case, pollinators will visit the preferred colour (value of A ) more often than expected by chance. The lower preference at smaller or larger A values could be associated with colour contrasts being highest at intermediate anthocyanin values (Van Der Kooi, 2021). Following Kokko (2007), we can model preference as increasing the relative frequency of the preferred colour such that

\overset{α}{true} = italicnα / ()(, italicnα + ()(, 1 - α))

, where n specifies the strength of the preference for A (Figure S2).…”

Section: Methodsmentioning

confidence: 99%

Modelling pollinator and nonpollinator selection on flower colour variation

2022

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Flower colour variation is ubiquitous within and between populations, which is why it has long been a focal point for studies of natural selection. This body of work has uncovered a wide range of selective agents, including pollinators, herbivores and various abiotic factors. Nevertheless, we lack an integrative framework for predicting the phenotypic outcome in terms of floral pigmentation when these forces act collectively and often in opposition. We here present such a framework through a model that incorporates selection on pigmentation at the vegetative phase (i.e. through survival to reproduction) and at the flowering phase (i.e. on pollinator attraction). We focus on anthocyanins as common class of pigments although the model is equally applicable to any compounds that can be jointly expressed in vegetative tissue and in flowers. We explore the dynamics of our model in a theoretical context and in four scenarios based on classic systems for studying selection on flower colour. Our model predicts that pollinators are the main driver for flower colour evolution, but selection on seedling survival plays a major role in the absence of pollen limitation, that is, if pollinator abundance is sufficiently high, or if pollinator preference is absent or weak (high variance in colour preference). In each of the case studies, our model recovered the predicted patterns of fitness for each floral morph given the strength and nature of selection. This work suggests that selection at the vegetative phase must act alone or be exceptionally strong to negate pollinator preference for particular colours. Nevertheless, the influence of differential survival associated with anthocyanin production leaves a clear signature on the fitness curves, suggesting that nonpollinator agents of selection can often be detected from empirical data. Synthesis: Overall, the application of this model to empirical systems will be key for understanding how flower colour diversity evolves and for predicting how changes in climate and pollinator communities may jointly alter evolutionary trajectories.

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\overset{α}{true} = italicnα / ()(, italicnα + ()(, 1 - α))

, where n specifies the strength of the preference for A (Figure S2).…”

Section: Methodsmentioning

confidence: 99%

Modelling pollinator and nonpollinator selection on flower colour variation

2022

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“…The flower perianth, particularly the colour and shape of petals and sepals, is essential for plant reproductive fitness, because it aids in attracting pollinators and/or deterring potential floral herbivores (van der Kooi et al 2019). The perianth can also protect the reproductive organs, particularly the pollen in bud stage and during pollen presentation, against the elements (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…A flower's shape plays a well-known role in mediating how pollen is placed on the pollinator's body and limiting nectar and pollen robbing (Benson et al 1975;Krupnick et al 1999;Strauss et al 2004;Caruso et al 2010;Koch et al 2017;van der Kooi et al 2021a), but it also determines how the reproductive organs are exposed to the outside world and what parts of the flower constitute the visual signal. For example, for erect flowers and inflorescences (e.g.…”

Section: Introductionmentioning

confidence: 99%

Why are the inner and outer sides of many flower petals differently coloured?

Fan,

Trunschke,

Ren

et al. 2024

Plant Biol J

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The flower perianth has various, non‐mutually exclusive functions, such as visual signalling to pollinators and protecting the reproductive organs from the elements and from florivores, but how different perianth structures and their different sides play a role in these functions is unclear. Intriguingly, in many species there is a clear colour difference between the different sides of the perianth, with colour patterns or pigmentation present on only one side. Any adaptive benefit from such colour asymmetry is unclear, as is how the asymmetry evolved. In this viewpoint paper, we address the phenomenon of flowers with differently coloured inner and outer perianth sides, focusing on petals of erect flowers. Guided by existing literature and our own observations, we delineate three non‐mutually exclusive evolutionary hypotheses that may explain the factors underlying differently coloured perianth sides. The pollen‐protection hypothesis predicts that the outer side of petals contributes to protect pollen against UV radiation, especially during the bud stage. The herbivore‐avoidance hypothesis predicts that the outer side of petals reduces the flower's visibility to herbivores. The signalling‐to‐pollinators hypothesis predicts that flower colours evolve to increase conspicuousness to pollinators. The pollen‐protection hypothesis, the herbivore‐avoidance hypothesis, and the signalling‐to‐pollinators hypothesis generate largely but not entirely overlapping predictions about the colour of the inner and outer side of the petals. Field and laboratory research is necessary to disentangle the main drivers and adaptive significance of inner–outer petal side colour asymmetry.

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“…An increase in pigment quantity should reduce brightness and increase chroma, because more pigmentation leads to more light being absorbed (e.g., Papiorek et al 2013;Van der Kooi 2021). A change in pigment composition (the relative quantities of different pigments) would likely shift floral hue because pigments differ in their absorption spectra.…”

Section: Introductionmentioning

confidence: 99%

Predictive links between petal color and pigment quantities in naturalPenstemonhybrids

Stevens

Wheeler

Williams

et al. 2023

Preprint

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Flowers have evolved remarkable diversity in petal color, in large part due to pollinator-mediated selection. This diversity arises from specialized metabolic pathways that generate conspicuous pigments. Despite the clear link between flower color and floral pigment production, studies determining predictive relationships between pigmentation and petal color are currently lacking. In this study, we analyze a dataset consisting of hundreds of natural Penstemon hybrids that exhibit variation in flower color, including blue, purple, pink, and red. For each individual hybrid, we measured anthocyanin pigment content and petal spectral reflectance. We found that floral pigment quantities are correlated with hue, chroma, and brightness as calculated from petal spectral reflectance data: hue is related to the relative amounts of delphinidin vs. pelargonidin pigmentation, whereas brightness and chroma are correlated with the total anthocyanin pigmentation. We used a partial least squares regression approach to identify predictive relationships between pigment production and petal reflectance. We find that pigment quantity data provide robust predictions of petal reflectance, confirming a pervasive assumption that differences in pigmentation should predictably influence flower color. Moreover, we find that reflectance data enables accurate inferences of pigment quantities, where the full reflectance spectra provide much more accurate inference of pigment quantities than spectral attributes (brightness, chroma, and hue). Our predictive framework provides readily interpretable model coefficients relating spectral attributes of petal reflectance to underlying pigment quantities. These relationships represent key links between genetic changes affecting anthocyanin production and ecological functions of petal coloration.

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How Much Pigment Should Flowers Have? Flowers With Moderate Pigmentation Have Highest Color Contrast

Cited by 8 publications

References 48 publications

Modelling pollinator and nonpollinator selection on flower colour variation

Modelling pollinator and nonpollinator selection on flower colour variation

Why are the inner and outer sides of many flower petals differently coloured?

Predictive links between petal color and pigment quantities in naturalPenstemonhybrids

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