Table 1.
Overview of all examined Nicotiana species showing some of their main features.
Fig 1.
Flowers of the examined Nicotiana species.
a) N. paniculata b) N. nudicaulis c) N. rustica d) N. palmeri e) N. langsdorffii f) N. knightiana g) N. attenuata h) N. benthamiana i) N. africana j) N. otophora k) N. glauca l) N. plumbaginifolia m) N. tabacum n) N. suaveolens o) N. nesophila p) N. acuminata q) N. stocktonii r) N. sylvestris s) N. alata t) N. longiflora
Table 2.
Concentrations and proportions of the main three sugars in nectar of different Nicotiana species.
Fig 2.
Boxplots of different nectar traits grouped into day- (left, white background) and night-flowering (right, grey background) species.
The data are arranged according to their main pollinators Trochilidae, Nectariniidae, Apidae, Sphingidae, Glossophaginae and self-pollinating species. (A) Boxplot diagram illustrating concentration of total sugars [mM]. (B) Sucrose-hexose-ratio is calculated by dividing sucrose concentration [g L-1] by the sum of glucose and fructose [g L-1]. (C) Boxplots illustrating the concentration of total amino acids [mM]. (D) Ratio sum of sugars-to-sum of amino acids. (E) Concentration of the amides glutamine and asparagine [mM]. (F) Total malate concentrations [mM]. (G) Concentration of the sum of inorganic anions (chloride, nitrate, phosphate, sulphate) [mM]. (H) Concentration of the sum of inorganic cations (potassium, sodium, ammonium, magnesium, calcium) [mM]. Different letters designate significantly different groups determined via ANOVA, post hoc Tukey’s HSD test and Kruskal-Wallis test for non-parametrical data (p ≤ 0.05).
Table 3.
Amino acid concentrations, proportions of the most abundant amino acids in nectar and the ratio of sugars to amino acids.
Fig 3.
Boxplots of sugar (A) and amino acid (B) amount in μmol per flower. Data were calculated by multiplication of the sugar or amino acid concentrations (Table 2 and Table 3) with the approximate nectar volume of each species. Results are grouped by their main pollinators Trochilidae, Nectariniidae, Apidae, Sphingidae, Glossophaginae and self-pollinating species. Different letters designate significantly different groups determined via ANOVA, post hoc Tukey’s HSD test and Kruskal-Wallis test for non-parametrical data (p ≤ 0.05).
Table 4.
Concentrations of malate, inorganic anions and cations as well as the proportions of the single ions in the nectar.
Fig 4.
Loadings and scatterplot of PCA scores in rotated space.
(A) Loadings of the original variables are shown as vectors in PCA space (B) The first principal component (PC 1) accounts for 24.4% and the second principal component (PC 2) accounts for 10.3% of the variation in the dataset. Eigenvalues are 2.837 for PC 1 and 1.846 for PC 2. Data (n = 99) are grouped both by main pollinators (colours) and sections (markings).
Table 5.
Results of the PERMANOVA: Degrees of freedom (df), pseudo-F (F), R2, and p-value (P).