Cryptic petal colouration decreases floral apparency and herbivory in nocturnally closing daisies

1. Floral apparency is shaped by both mutualistic and antagonistic interactions that can act in opposing ways. Pollinators are expected to select for more visually apparent flowers, but this likely trades off against the potentially severe fitness costs of damage to apparent flowers by floral herbivores. One way in which flowers that close during parts of the day might circumvent this trade-off, is by evolving less visible lower petal surfaces that are inconspicuous to herbivores when flowers are closed. 2. Here we used visual system modelling and herbivory experiments to test whether petal surfaces that are exposed when flowers are closed are cryptically coloured. We collected lower and upper petal surface spectra for 77 Asteraceae species from Namaqualand, South Africa. This included closing species that expose their lower petal surfaces for 5 to 6 daylight hours, and non-closing species that do not expose their lower surfaces. We used these contrasting groups to test the expectation ...