Intraspecific variation of Bothrops pictus venom reveals geographic and phylogenetic patterns of functional diversity

Snake venom composition is shaped by ecological, biological, and evolutionary pressures, with intraspecific variability playing an important role in venom evolution and toxin diversity. Bothrops pictus, an endemic viper of the Peruvian coastal desert, has been the subject of biochemical and proteomic studies; however, interindividual venom variation among geographically distinct coastal populations remains insufficiently characterized. Here, we evaluated toxinological variation using an integrative approach combining enzymatic assays, electrophoretic and chromatographic profiling, immunological analysis, and phylogenetic inference across eight adult individuals from geographically distinct populations. Our results revealed pronounced interindividual variation in both venom composition and enzymatic activity. Hyaluronidase (HYAL) and L-amino acid oxidase (LAAO) showed the highest variability, whereas proteolytic activity remained comparatively conserved. Intermediate variation was observed for amidolytic, phospholipase A₂ (PLA₂), and coagulant activities. Protein and chromatographic analyses further supported compositional differences among individuals. Phylogenetic analysis identified two well-supported clades corresponding to northern and southern populations, with partial correspondence between genetic structure and functional variation. Despite this heterogeneity, immunoreactivity against the commercial polyvalent antibothropic antivenom remained comparatively conserved across individuals. Together, these findings demonstrate that both conserved and variable venom traits coexist within B. pictus populations and highlight the value of integrating compositional, functional, immunological, and phylogenetic approaches to investigate intraspecific venom variation.