Interpopulation variation in nectar production in Aconitum columbianum (Ranunculaceae)

Abstract

In Aconitum columbianum there are extreme interpopulation differences in rates of nectar secretion per flower. Since nectar sugar concentration varies little among populations, increased nectar secretion results in a greater mass of sugar per flower for pollinator attraction. These differences in the amount of reward offered per flower account at least in part for observed higher levels of pollinator activity in populations with high nectar production. Nectar production is correlated also with nectary depth, i.e., flowers in populations with deep nectaries have higher rates of nectar secretion than those with shallow nectaries. Nectary depth differences adapt populations to different pollinator-types. Populations with deeper nectaries are adapted to pollination by bumblebees with longer tongues and more specialized foraging behaviors. In conclusion, there are basic differences in pollination ecology among geographical races of a. columbianum, which are indicated by correlated interpopulution differences in (1) nectar production, (2) level of pollinator activity, (3) nectar depth, and (4) pollinator-type.

Nectarless flowers: ecological correlates and evolutionary stability

“…Thus "visit more flowers" did not seem to work in this species. Brink and deWet (1980) did not observe any correlation between the length of corolla tube and the proportion of nectarless flowers as predicted by the Bell (1986) model. Smithson and Gigord (2001) showed that bumble bees spent more time searching on rewardless flowers resulting in a male advantage.…”

Does size matter? Bumblebee behaviour and the pollination of Cytisus scoparius L. (Fabaceae)

“…frequently correlated with the size of the floral reward (nectar and/or pollen) [5,10,16,51,54]. Furthermore, foragers tend to select and visit more flowers on plants or patches with large floral display sizes in order to reduce travel times between flowers [3,22,23,32,46,47].…”

Préliminaires sur la production de nectar chez trois espèces de Vaccinium

“…En ce qui concerne la concentration totale en sucres, Free (1955), Pouvreau (1974), Corbet (1978) et Eickwort et Ginsberg (1980) (Bigras-Huot et al, 1973;Roberts, 1978;Cane et al, 1985;Mohr et Kevan, 1987) (Roberts, 1978;Pleasants, 1983), la localisation de la fleur (Hocking, 1968;Pleasants, 1983), la taille de cette fleur (Brink et de Wet, 1980), la taille de la plante (Harder, 1985), la localisation de l'individu (Zimmermann et Pyke, 1988), le moment dans la journée (Corbet et al, 1979), les conditions climatiques (Hocking, 1968;Southwick et al, 1981), le prélèvement par des pollinisateurs (Corbet et al, 1979;Pleasants, 1981) …”