Evolutionary patterns of loricariid trophic diversification revealed by assemblage centroid-standardized isotope vector analysis (ACSIVA) of C and N stable isotope data (Figure3; See Additional file
: Figures 3–10 for isotope biplots of all local assemblages examined). Cladograms A and B represent the hypothesized ancestral distributions of lineages along a vertical axis of 15 N-enrichment relative to assemblage centroid (pink to red being 15 N-enriched relative to centroid, light green to green being 15 N-depleted relative to centroid). Cladogram A represents a phylogenetic regression of 649 individual vectors (Figure 3A) grouped by genus irrespective of site (see Additional file 2: Figure S1 for a full size version of this phylogeny), and cladogram B represents a regression of 120 mean genus x site vectors (Figure 3 C). Circle plots illustrate the direction of mean genus x site vectors for each genus and statistical significance of the mean vector is indicated by * (Rayleigh’s Z test: P < 0.05) or † (0.10 > P > 0.05; Tables 1, 2). Cladogram C resulted from the same analysis as B, but is color-coded to reflect hypothesized distributions of ancestral lineages along a horizontal axis of 13 C-enrichment relative to assemblage centroid (see Additional file 3: Figure S2 for a full size version of this phylogeny). Oral disk photos by N. K. Lujan or M. H. Sabaj Pérez.