How do visitation patterns vary among pollinators in relation to floral display and floral design in a generalist pollination system?

Diverse pollinator assemblages may impose complex selection and thus limit specialisation to particular pollinators. Previous work has concentrated on how visitation rates of different pollinators vary in space and time and h ow pollinators may vary in efficiency. In this study I quantify variation i n visitation rates and foraging behaviour of different insect types (1) in space and time and (2) in relation to variation in floral design (flower si ze and form) and floral display (number of open flowers) for the distylous clonal shrub Jasminum fruticans. Mean visitation rate showed a significant interaction between insect type and population for seven populations in one year, and between insect types and years for a single population over 3 ye ars. There was also a significant interaction between insect type and popul ation for the proportion of flowers visited. In general the number of visit s was positively related to the number of open flowers in a patch, but anal yses by insect type showed that this was only true for bee flies and butter flies. Short-tongued bees showed a positive relationship between visitation rate and the number of open flowers on the focal stem, and hawkmoths and b utterflies made more visits to plants with larger flowers. Hawkmoths were t he only insect type to show a positive relation between the number of flowe rs visited per foraging bout and flower size. The significant differences b etween different insect types in patterns of variation in visitation rates in response to floral design and display may act to diversify selection on floral traits, and thereby constrain specialisation of the plant to particu lar pollinators.