*2.1. Individual Variation of Venom Composition Is Associated with Habitats*

Chromatographic analyses by RP-HPLC were our first approach to investigate the individual variability of *B. atrox* venoms among the specimens collected in each habitat: forest, pasture, degraded area, and floodplain. Overall, similar profiles can be seen in all chromatograms, although the relative heights or areas of peaks varied greatly between venoms even among snakes collected at the same habitat (Figure 1 and Supplementary Figure S1, for individual chromatograms). In all venom chromatographies, the highest peaks were eluted after 80 min, while peaks eluted between 50 and 70 min showed the most variable area percentages, being higher in floodplain venoms and lower in pasture venoms. According to our previous study [15], Snake Venom Metalloproteinases (SVMPs) are the main components eluted after 80 min, while Phospholipases A2 (PLA2s), C-type Lectin-like proteins (CTLs), and Snake Venom Serine proteinases (SVSPs) are the prevalent protein families in the fractions eluted in the intermediate steps (50–70 min).

**Figure 1.** Chromatographic profiles of *B. atrox* venoms from different habitats west of Pará State, Brazilian Amazon. Individual venom samples (5 mg) of *B. atrox* snakes collected at the forest, pasture, degraded area, or floodplain were applied to a Vydac C-18 column. Mobile phases used were 0.1% TFA in water (solution A) or 0.1% TFA in acetonitrile (solution B). Proteins were gradient-eluted at 2 mL/min (5% B for 5 min, 5–15% B over 10 min, 15–45% B over 60 min, 45–70% B over 10 min, 70–100% over 5 min, and 100% B over 10 min). Separation was monitored at 214 nm.
