DOI: 10.5061/dryad.pg4f4qrn4
title: Do visual traits honestly signal floral rewards at community level?

description: 1. The high variability observed in floral traits has been interpreted as
 resulting from the adaptation of plants to pollinators, as the latter
 present innate preferences for specific floral traits and impose selection
 over them. However, some pollinators such as bees can learn to associate
 floral signals with rewards, thus increasing floral constancy on more
 rewarding flowers. The integration of all these rewards and cues is
 markedly important at community level, where co-flowering species compete
 for pollinators. 2. In order to verify the honesty of the above mentioned
 signals, we examined the association between floral visual signals (size,
 colour, symmetry and floral display) and rewards (pollen and nectar) for
 98 species in a Mediterranean community. The associations between floral
 traits were analysed considering the phylogenetic relationship between the
 different species. 3. Flower colour, size, pollen volume, or amount of
 sucrose exhibited no phylogenetic signal, which suggests an adaptive
 evolution in response to different conditions in the pollinator community.
 Flower size was seen to constitute the most honest signal for pollinators,
 as this was significantly associated with quantities of pollen and nectar.
 In contrast, nectar concentration was observed to be positively associated
 with chromatic contrast. We detected no relationship between flower shape
 and rewards, on the one hand, or between flower display and rewards, on
 the other. 4. Our study unequivocally demonstrates the correlation between
 rewards and the visual signals perceived by bees, the most effective
 pollinators in the Mediterranean Basin. In the community studied, bees
 employed flower size at longer distances and chromatic contrast at shorter
 distances to predict rewards. The limited number of studies existing in
 this sense indicates that this kind of association appears to be community
 specific.
description: The dataset includes measures of floral reward production and
 visual floral traits of 98 species in a Mediterranean community. For
 reward production data we profited from two earlier extensive studies on
 nectar and pollen production in the same community (Ortiz, 1991; Talavera,
 Herrera, Arroyo, Devesa, & Ortiz, 1988) and, for species not
 included in those studies, we assessed reward production following the
 same procedures employed therein in such a way that both datasets were
 comparable. For data on floral size and symmetry we used the
 <i>Flora Vascular de Andalucía Occidental</i> by Valdés,
 Talavera & Fernández-Galiano (1987). We estimated floral display
 size as the number of flowers at anthesis of a plant at its peak of
 flowering. For floral colour data, we used a spectrometer to obtain
 spectral reflection functions of petals, and from those functions, we
 calculated reflectance amplitude and spectral purity. We also plotted
 those spectral functions in the bee vision model by Chittka (1992) to
 calculate the remainders colour parameters: green contrast, brightness
 contrast, chromatic contrast, X and Y coordinates in the model, and bee
 colour. References -
 Chittka, L. (1992). The colour hexagon: a chromaticity diagram based on
 photoreceptor excitations as a generalized representation of colour
 opponency. Journal of Comparative Physiology A, 5, 533–543. doi: https://doi.org/10.1007/BF00199331. - Ortiz, P. L. (1991). <i>Melitopalinología en Andalucía Occidental. Tesis Doctoral en Microfichas</i>. Sevilla: Universidad de Sevilla. - Talavera, S., Herrera, J., Arroyo, J., Devesa, J. A., & Ortiz, P. L. (1988). Estudio de la flora apícola de Andalucia Occidental. <i>Lagascalia</i>, <i>15</i>(1), 567–592. - Valdés, B., Talavera, S., & Fernández-Galiano, E. (1987). <i>Flora Vascular de Andalucía Occidental</i>. Barcelona: Ketres Editora.  
description: All figures represent mean values for each species. We assessed
 floral display size only in a subset of the studied species, and there are
 some missing data for reward production and flower size.