Abstract
The plant kingdom offers a bewildering diversity in floral colours, but the variation in the flowers’ spectral characteristics and to what extent this was driven by pollinators remains largely unknown. Whereas the chemical properties of floral pigments and their evolution have received considerable scientific attention, the complex optical principles of the flower’s light reflecting structures are poorly understood. Flowers with similar pigments and hues often differ strongly in brightness, saturation, glossiness and contrast, but how their optical properties have evolved in different taxa has not been studied. The central theme of the present proposal is to test our recently developed hypothesis that light scattering is crucial for maximising the flower’s conspicuousness to pollinators. This project will unravel the evolution of the optical characteristics of flowers in the context of their phylogeny and pollinator perspective. In a taxonomic-wide screen, using a combination of correlational, experimental and modelling approaches, I will study evolutionary gains and losses of floral traits. I will apply a wide array of physical techniques, e.g. spectrophotometry, interferometry and optical modelling, and complementary biological approaches, including anatomical, physiological and taxonomic analyses built on sophisticated phylogenetic models. The spectral characteristics of flowers will be analysed with a “pollinator-subjective view” using both established knowledge on diurnal pollinator vision as well as new experimental findings obtained in this project on nocturnal pollinator vision. The results will reveal the crucial anatomical properties that determine vividly coloured flowers, how flower colours evolved, and how this is influenced by phylogenetic ancestry and pollination system. The knowledge acquired through this multifaceted approach will be of central interest for understanding plant-pollinator interactions, which is appealing to biologists, the general public, and for applied usage in the plant and flower breeding industry.
Netherlands