Casper J Van der Kooi

Casper J Van der Kooi
University of Groningen | RUG

PhD

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43
Publications
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878
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Publications

Publications (43)
Article
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Environmental shifts and life-history changes may result in formerly adaptive traits becoming non-functional or maladaptive. In the absence of pleiotropy and other constraints, such traits may decay as a consequence of neutral mutation accumulation or selective processes, highlighting the importance of natural selection for adaptations. A suite of...
Article
Full-text available
The coloration of flowers is due to the wavelength-selective absorption by pigments of light backscattered by structures inside the petals. We investigated the optical properties of flowers using (micro)spectrophotometry and anatomical methods. To assess the contribution of different structures to the overall visual signal of flowers, we used an op...
Article
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Buttercup (Ranunculus spp.) flowers are exceptional because they feature a distinct gloss (mirror-like reflection) in addition to their matte-yellow coloration. We investigated the optical properties of yellow petals of several Ranunculus and related species using (micro)spectrophotometry and anatomical methods. The contribution of different petal...
Article
Full-text available
Changes from sexual reproduction to female-producing parthenogenesis (thelytoky) have great evolutionary and ecological consequences, but how many times parthenogenesis evolved in different animal taxa is unknown. We present the first exhaustive database covering 765 cases of parthenogenesis in haplodiploid (arrhenotokous) arthropods, and estimate...
Article
Full-text available
Background: 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...
Article
Full-text available
Background: The colours of flowers are of key interest to plant and pollination biologists. An increasing number of studies investigates the importance of saturation of flower colours (often called "spectral purity" or "chroma") for visibility to pollinators, but the conceptual, physiological and behavioural foundations for these metrics as well a...
Article
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Studies on animal colour vision typically focus on the chromatic aspect of colour, which is related to the spectral distribution, and disregard the achromatic aspect, which is related to the intensity (“brightness”) of a stimulus. Although the chromatic component of vision is often most reliable for object recognition because it is fairly context i...
Article
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Nutrient deficiency is known to constrain plant growth in numerous ways, but how it impacts floral displays and pollination success remains unclear. Here we investigate how insufficient availability of sulphur-a vital plant nutrient that is a limiting factor in natural and agricultural regions throughout the world-influences the production of flora...
Article
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Floral pigments are a core component of flower colors, but how much pigment a flower should have to yield a strong visual signal to pollinators is unknown. Using an optical model and taking white, blue, yellow and red flowers as case studies, I investigate how the amount of pigment determines a flower’s color contrast. Modeled reflectance spectra a...
Article
The majority of flowering plants relies on animal pollinators for sexual reproduction and many animal pollinators rely on floral resources. However, interests of plants and pollinators are often not the same, resulting in an asymmetric relationship that ranges from mutualistic to parasitic interactions. Our understanding of the processes that under...
Article
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Flavonoid pigments are key determinants of flower colors. As absorption spectra of flavonoids are known to be severely pH-dependent, cellular pH will play a crucial role in flower coloration. The flavonoids are concentrated in the vacuoles of the flowers’ epidermal cells, and thus the pigments’ absorption spectra are modulated by the vacuolar pH. H...
Article
Full-text available
Main conclusion: Stomatal aperture in maize is not affected by exposure to a subtoxic concentration of atmospheric H2S. At least in maize, H2S, thus, is not a gaseous signal molecule that controls stomatal aperture. Sulfur is an indispensable element for the physiological functioning of plants with hydrogen sulfide (H2S) potentially acting as gaso...
Article
Full-text available
Color vision is widespread among insects but varies among species, depending on the spectral sensitivities and interplay of the participating photoreceptors. The spectral sensitivity of a photoreceptor is principally determined by the absorption spectrum of the expressed visual pigment, but it can be modified by various optical and electrophysiolog...
Article
Full-text available
The majority of angiosperms have flowers with conical epidermal cells, which are assumed to have various functions, such as enhancing the visual signal to pollinators, but detailed optical studies on how conical epidermal cells determine the flower’s visual appearance are scarce. Here we report that conical epidermal cells of Mandevilla sanderi flo...
Article
Full-text available
For more than a century there has been a fascination with the surprisingly rapid rise and early diversity of flowering plants (angiosperms). Darwin described the seemingly explosive diversification of angiosperms as an “abominable mystery,” and debates continue about the origin and processes driving angiosperm speciation. Dating the origin of angio...
Article
Full-text available
The majority of angiosperms have flowers with conical epidermal cells, which are assumed to have various functions, such as enhancing the visual signal to pollinators, but detailed optical studies on how conical epidermal cells determine the flower’s visual appearance are scarce. Here we report that conical epidermal cells of Mandevilla sanderi flo...
Technical Report
Full-text available
EKLIPSE received a request by Pollinis on the 30th of June 2018, to produce an overview of the current knowledge and research gaps related to the impacts of pesticide and fertilizer use in farmland on the effectiveness of adjacent pollinator conservation measures. The call was answered through a Joint Fact Finding approach, including a workshop on...
Article
Full-text available
The epidermal cells of flowers come in different shapes and have different functions, but how they evolved remains largely unknown. Floral micro‐texture can provide tactile cues to insects, and increases in surface roughness by means of conical (papillose) epidermal cells may facilitate flower handling by landing insect pollinators. Whether flower...
Article
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Sex determination has evolved in a variety of ways and can depend on environmental and genetic signals. A widespread form of genetic sex determination is haplodiploidy, where unfertilized, haploid eggs develop into males and fertilized diploid eggs into females. One of the molecular mechanisms underlying haplodiploidy in Hymenoptera, the large inse...
Article
Full-text available
A prime example of plant–animal interactions is the interaction between plants and pollinators, which typically receive nectar and/or pollen as reward for their pollination service. While nectar provides mostly carbohydrates, pollen represents the main source of protein and lipids for many pollinators. However, the main function of pollen is to car...
Article
Full-text available
Background: Obtaining an optimal flower temperature can be crucial for plant reproduction because temperature mediates flower growth and development, pollen and ovule viability, and influences pollinator visitation. The thermal ecology of flowers is an exciting, yet understudied field of plant biology. Scope: This review focuses on several attri...
Article
Full-text available
The flowers of poppies (Papaveraceae) exhibit bright colours, despite their thin and floppy petals. We investigated the optical properties of flowers of Papaver rhoeas, P. dubium, Meconopsis cambrica and Argemone polyanthemos using a combined approach of anatomy, spectrophotometry and optical modelling. The petals of Papaver flowers are composed of...
Article
Full-text available
Innate colour preferences promote the capacity of pollinators to find flowers, although currently there is a paucity of data on how preferences apply to real flowers. The Australian sugarbag bee (Tetragonula carbonaria Sm.) has innate preferences for colours, including UV-absorbing white. Sugarbag bees are pollinators of the terrestrial orchid Cala...
Preprint
Full-text available
Sex determination has evolved in a variety of ways and can depend on environmental and genetic signals. A widespread form of genetic sex determination is haplodiploidy, where unfertilized, haploid eggs develop into males and fertilized diploid eggs into females. One of the molecular mechanisms underlying haplodiploidy in Hymenoptera, a large insect...
Article
Full-text available
Many asexual animal populations comprise a mixture of genetically different lineages, but to what degree this genetic diversity leads to ecological differences remains often unknown. Here, we test whether genetically different clonal lineages of Aptinothrips grass thrips differ in performance on a range of plants used as hosts in natural population...
Data
Figure S1. Frequency of parthenogenesis in Chalcidoidea. Phylogeny from Heraty, et al. (1). Total number of species per family was taken from Noyes (2). Figure S2. Frequency of parthenogenesis in Symphyta. Phylogeny from Klopfstein, et al. (3) and the total number of species was taken from Taeger and Blank (4). 14 families with fewer than 80 speci...
Article
The blue colours of the speculum of the mallard (Anas platyrhynchos), both male and female, and the green head feathers of the male arise from light interacting with stacks of melanosomes residing in the feather barbules. Here, we show that the iridescent colours can be quantitatively explained with an optical multilayer model by using a position-d...
Article
Full-text available
The reproductive performance of plants depends on the temperature of the flower. A recent study reports the mechanistic basis of flower head orientation in sunflowers and provides intriguing hints as to its functional significance.
Article
Full-text available
Main conclusion: An absorbing-layer-stack model allows quantitative analysis of the light flux in flowers and the resulting reflectance spectra. It provides insight in how plants can optimize their flower coloration for attracting pollinators. The coloration of flowers is due to the combined effect of pigments and light-scattering structures. To i...
Article
Full-text available
Exposure of plants to elevated CO2 (eCO2) has a number of physiological effects, including increased photosynthetic carbon fixation and decreased stomatal conductance, resulting in greater growth and yield and also improved water use efficiency. Therefore, eCO2 is considered to ameliorate the adverse effects of drought. To test this assumption in e...
Article
Full-text available
Competition for pollinators occurs when in a community of flowering plants several simultaneously flowering plant species depend on the same pollinator. Competition for pollinators increases interspecific pollen transfer rates, thereby reducing the number of viable offspring. In order to decrease interspecific pollen transfer, plant species can dis...
Article
Full-text available
Parthenogenesis - the ability to produce offspring from unfertilized eggs - is widespread among invertebrates and now increasingly found in normally sexual vertebrates. Are these cases reproductive errors or could they be a first step in the emergence of new parthenogenetic lineages? Copyright © 2015 Elsevier Ltd. All rights reserved.
Article
Full-text available
The color of natural objects depends on how they are structured and pigmented. In flowers, both the surface structure of the petals and the pigments they contain determine coloration. The aim of the present study was to assess the contribution of structural coloration, including iridescence, to overall floral coloration. We studied the reflection c...
Article
Full-text available
Asexual lineages can derive from sexual ancestors via different mechanisms and at variable rates, which affects the diversity of the asexual population and thereby its ecological success. We investigated the variation and evolution of reproductive systems in Aptinothrips, a genus of grass thrips comprising four species. Extensive population surveys...

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Projects (2)
Project
Floral colour evolution in angiosperms