DOI: 10.5061/dryad.4mw6m90d9
title: Unravelling the mystery of red flowers in the Mediterranean Basin: How to be conspicuous in a place dominated by hymenopteran pollinators

description: Red-flowered species have traditionally been related to ornithophily, and
 the 'bee avoidance' hypothesis, i.e. red flower coloration is a
 way to reduce visits from hymenopterans, has been proposed to explain this
 association. In the Mediterranean Basin, ornithophily is almost absent,
 and hymenopterans are the most common group of pollinators. The fact that
 hymenopterans are virtually red-blind raises the question of how
 red-flowered species are pollinated in this region. Are these flowers
 pollinated by other groups of red-sensitive insects such as lepidopterans
 and coleopterans, or do they have visual cues that make them attractive to
 hymenopterans? We examined the reflectance spectra of 51 red-flowered
 species from the Mediterranean Basin and modelled these spectra in the
 visual system of hymenopterans, dipterans, coleopterans, and lepidopterans
 to obtain colour and conspicuousness. According to their reflectance
 curves, species were classified as pure red and UV-red flowers, and the
 presence of more than one flower colour (patterned flowers) was studied.
 We evaluated the match between flower reflectance spectra and the maximum
 discrimination abilities of hymenopteran and lepidopteran visual system.
 All these metrics were analysed in a phylogenetically explicit framework,
 and a literature review of potential pollinators was performed. The vast
 majority of red-flowered species in the Mediterranean Basin are
 potentially pollinated by hymenopterans, and only three species are
 exclusively visited by coleopterans. We found that 90% of these species
 showed at least one colour signal strategy that helps to enhance
 conspicuousness to hymenopterans: to produce UV-red flower type spectra
 and/or patterned flowers. The UV-red colour showed a significant
 phylogenetic signal, but the presence of patterned flowers did not. Even
 though the red-flowered species of the Mediterranean Basin did not
 optimally match the colour vision of hymenopterans or lepidopterans, the
 presence of patterned and UV-red colours suggests an improvement in
 detection and discrimination by hymenopterans. The bee-avoidance
 hypothesis seems to be ruled out for the red-flowered species of the
 Mediterranean Basin. Our results suggest that red-flowered species are
 mostly pollinated by hymenopterans and show different flower colour signal
 strategies that can be interpreted as signs of adaptation to these
 pollinators.
description: We sampled 51 red-flowered species from the Mediterranean Basin
 and recorded their reflectance spectra in the UV and visible light
 spectrum with a spectrophotometer. Reflectance data was processed using
 PAVO package (Maia
 et al.,
 2019) in R
 Studio. We also assesed the presence of UV or visible colour patterns in
 flowers and measure its reflectance spectra. The data
 set includes values for main colour (red) and pattern of the sampled
 species for the pollinators visual models studied namely hymenopterans,
 dipterans, coleopterans and lepidopterans.  Data encompass chromatic
 contrast values, spectral purity and location of marker points using
 the online tool 'Spectral-MP'
 developed by Dorin et al.
 (2020).
 References: - Dorin, A., Shrestha, M., Herrmann, M., Burd, M.
 & Dyer, A. G. (2020). Automated calculation of
 spectral-reflectance marker-points to enable analysis of plant
 colour-signaling to pollinators. MethodsX, 7, 100827.
 http://dx.doi.org/10.1016/j.mex.2020.100827 - Maia, R., Gruson, H., Endler, J. A. & White, T. E. (2019). PAVO 2: new tools for the spectral and spatial analysis of colour in R. Methods in Ecology and Evolution, 10(7), 1097-1107. https://doi.org/10.1111/2041-210X.13174
description: Data set is provided as a ".xlsx" file.