Pollinator abundance and behavior on Aconitum lycoctonum (Ranunculaceae): an analysis of the quantity and quality components of pollination.

The yellow-flowered monkshood Aconitum lycoctonum has variable degrees of inbreeding among populations, despite being primarily bee-pollinated. Here we examined the pollination ecology of A. lycoctonum . We investigated pollinator community and frequency in four populations at two altitudes over two years. We found that flowers were more often visited at low elevation than at high elevation. However, because flowers lived longer at high elevation than at low elevation, and plants at high elevation had more flowers than at low elevation, the overall chance of a plant being visited may be greater at high elevation. Breeding system experiments showed that at least some populations of A. lycoctonum were self-compatible and also were not completely protandrous. Thus selfing, especially by geitonogamous pollen, will be common if pollinators often visit several flowers within a plant, as we found to be true for the main pollinator (bumblebees) of A. lycoctonum . Although the stereotypical behavior of bees is to move upwards, 17% of the within-plant movements of the main pollinator (Bombus gerstaeckeri ) were downwards, i.e. from a male-phased to a female-phased flower because the flowers open from the bottom to the top of the plant. Other pollinators of A. lycoctonum moved less often within plants. We conclude that in addition to differences in self-compatibility, differences in pollinator abundance and behavior could have led to variation in the realized mating system in different A. lycoctonum populations. [ABSTRACT FROM AUTHOR]