Differences in pollination success between local and foreign flower color phenotypes: a translocation experiment withGentiana lutea(Gentianaceae)

Abstract

BackgroundThe adaptive maintenance of flower color variation is frequently attributed to pollinators partly because they preferentially visit certain flower phenotypes. We tested whetherGentiana lutea—which shows a flower color variation (from orange to yellow) in the Cantabrian Mountains range (north of Spain)—is locally adapted to the pollinator community.MethodsWe transplanted orange-flowering individuals to a population with yellow-flowering individuals and vice versa, in order to assess whether there is a pollination advantage in the local morph by comparing its visitation rate with the foreign morph.ResultsOur reciprocal transplant experiment did not show clear local morph advantage in overall visitation rate: local orange flowers received more visits than foreign yellow flowers in the orange population, while both local and foreign flowers received the same visits in the yellow population; thus, there is no evidence of local adaptation inGentiana luteato the pollinator assemblage. However, some floral visitor groups (such asBombus pratorum,B. soroensis ancaricusandB. lapidarius decipiens) consistently preferred the local morph to the foreign morph whereas others (such asBombus terrestris) consistently preferred the foreign morph.DiscussionWe concluded that there is no evidence of local adaptation to the pollinator community in each of the twoG. luteapopulations studied. The consequences for local adaptation to pollinator onG. luteaflower color would depend on the variation along the Cantabrian Mountains range in morph frequency and pollinator community composition.