Abstract
Venomous snakebites kill over 100,000 people annually worldwide, and permanently disable many more. One of the key obstacles to the treatment of snakebites is the extreme variation in venom composition, even between loosely related species and within species. In this presentation, I will explore the evidence for different potential selection pressures acting on venom composition, primarily for the functions of foraging and defence. A considerable number of studies has provided evidence for the role of selection for diet as a major driver of venom evolution across a variety of groups. In contrast, evidence for selection for a defensive role is limited and patchy, with a few notable exceptions. Our ability to understand the selective pressures affecting venom composition is hindered by a remarkable paucity of data on the natural history of venom and venom use by snakes in the wild. Citizen science contributions, especially chance observations of interactions between snakes and their prey and predators, are key to expanding our understanding of the ecological context of venom evolution.