Figure 5. Isotopic signature (δ¹⁵N) of samples and assessment of myrmecotrophy.

(a) Mean δ¹⁵N compared between C. schmitzi, plants occupied by C. schmitzi (referred as PA plants) and plants that have not been occupied by C. schmitzi (referred as PnoA_{-no hole}). These three signatures were used to estimate the percentage of foliar nitrogen derived from the ants. The error bars denote 1 S.E. (b) Foliar δ¹⁵N of N. bicalcarata as an increasing function of C. schmitzi occupation rate. As a consequence the percentage of foliar N derived from the ants also increased with ant occupation rate.