Different points of view in a changing world: The tobacco tree flowers through the eyes of its pollinators in native and non-native ranges

Abstract

Different pollinators show distinct visual and cognitive abilities that can influence floral colour evolution. Nicotiana glauca is a South American hummingbird-pollinated plant that has become a significant invasive of semi-arid parts of the world, where it is visited by local animals like sunbirds in South Africa or diurnal hawkmoths in Spain. We measured corolla reflectance spectra from native and non-native populations encompassing the different pollination contexts. Flower colour loci were represented in the visual space of tetrachromatic birds and trichromatic hawkmoths. Variation in corolla reflectance spectra was revealed, both across pollination contexts and among populations. From the pollinators' point of view (hummingbirds, sunbirds and hawkmoths), flowers from native populations were, in general, significantly discriminated from those of the non-native populations, which mostly were not discriminated as different from each other. We discuss our findings under the hypothesis of pollinator-mediated colour selection and alternative evolutionary processes that may occur during invasions.