Generalist‐pollinated <i>Arabis alpina</i> exhibits floral scent variation at multiple scales

Plants that depend on animals for reproduction often use complex floral traits to attract pollinators. Floral scent is recognized as part of the pollinator attraction module and can be shaped by plant‐pollinator interactions. In recent decades, research has started to reveal the dynamic properties of floral scent, identifying patterns of spatial and temporal variation in floral scent emissions at various scales. Here, we investigate the levels at which floral scent varies in two populations of the generalist, perennial herb Arabis alpina (Brassicaceae) and if scent variation co‐varies with pollinator activity, which would be expected if scent production is costly. First, we show the potential for both floral scent and pollinator communities to vary at a small geographic scale, between neighboring populations located some 4 km apart. Then, we investigate diel variation in floral scent emission rate and pollinator activity to test for synchronization between plants and pollinators. Further, we sampled volatiles from dissected floral parts to determine where floral scent compounds are produced in A. alpina . The two populations were pollinated by partly different communities of diurnally active insects, and scent composition, specifically petal and reproductive organ scent, differed between the two neighboring populations. However, we found no evidence of a diel synchronization between floral scent emission and insect activity, as A. alpina emits similar amounts of scent regardless of time of day and temperature. Whereas the spatial variation (within flowers, among populations) suggests specific and localized functions of the floral scent, the constant and stable scent emission indicates a low production and maintenance cost of the floral volatiles in this system.