Figure 1. Characterization of 52 plants from different natural populations.
Mean standing nectar volume (n = 6 to 8 flowers/plant), nectar sugar concentration (n = 6 to 8 flowers/plant), and benzylacetone (BA) level (n = 1 flower/plant). Nectar volume and sugar concentration were measured from newly opened flowers at the end of the nectar production period (5–6 am). BA level was measured over the night (8 pm–6 am) and calculated from peak areas normalized using tetralin as an internal standard. Inset: mean (+SE) standing nectar volume in newly opened flowers at the end of the nectar production period (5–6 am) in three native phenotypes (Ut-WT, 83, and 84; n = 7–9) found within a separate sample of 424 native Nicotiana attenuata plants that were screened for the presence of nectar. Asterisks indicate significant differences, as informed by a nonparametric Mann–Whitney U-test p < 0.05.