Presence of BilR in different animal metagenomes. Plots show the composition of bilirubin reductase clades in each sample. Samples are grouped by animal species, and the diet of each animal is shown in the graphics to the right of each animal’s name. The significantly enriched bilirubin reductase types, based on Wilcoxon rank sum tests, are shown by the colored circles to the left of each animal’s name.