Figure 1.
Trophic discrimination factors.
Linear regression analysis of trophic discrimination factors (Δ15N) deriving from A) CSIA analysis, and B) bulk 15N analysis. Each point represents the trophic discrimination factor of an individual organism. Discrimination factors depicted at trophic levels 2, 3, and 4 represent the isotopic shifts from levels 1 to 2, 2 to 3, and 3 to 4, respectively.
Figure 2.
Trophic position estimates, controlled-feeding trials.
Trophic position estimates (mean ± 1σ) from the controlled-feeding trials. A) Plots of observed trophic positions vs. their corresponding known trophic positions. Black circles indicate TPglu-phe estimates, and gray triangles indicate TPbulk estimates. The dotted line (y = x) represents perfect agreement between observed and known trophic positions. B) Degree of departure between the observed and known trophic positions (mean ± 1σ).
Figure 3.
Trophic position estimates, apple orchard.
Trophic position estimates (mean ± 1σ) from an apple orchard food chain (pictured): apple leaves, apple aphid, hover fly, parasitoid, and hyperparasitoid. Observed trophic positions are plotted against expected trophic positions. Black circles and gray triangles respectively indicate TPglu-phe and TPbulk estimates. The dotted line (y = x) represents perfect agreement between observed and expected trophic positions.