Venom composition of the Iberian adder (Vipera seoanei) from northern Portugal reveals limited sex and size variation

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Venom composition of the Iberian adder (Vipera seoanei) from northern Portugal reveals limited sex and size variation

Abstract

Snake venom is a complex and dynamic ecological trait, with high potential for intraspecific variation. In this study, the venom composition of the Iberian adder (Vipera seoanei) from the Peneda Mountains of northern Portugal was investigated to explore whether venom varies with body size and sex. Venom proteomes from six individuals representing juvenile, subadult, and adult males and females were characterised using LC–MS/MS, while individual variation was assessed from SDS–PAGE profiles of 18 snakes. LC–MS/MS identified 144 proteins, dominated by phospholipases A2 (PLA2), snake venom serine proteases (svSP), and C-type lectin-related proteins (CTL). Descriptive comparisons revealed contrasting individual profiles, particularly between the juvenile male, characterised by high svSP and svMP abundance, and the juvenile female, characterised by high PLA2 abundance. Subadult proteomes were dominated by PLA2, whereas adults had high PLA2 and svSP abundance. However, PERMANOVA of the SDS–PAGE profiles detected no significant effects of ontogenetic class or sex on venom composition, suggesting that the observed proteomic patterns should be interpreted with caution. This study provides an initial characterisation of ontogenetic and sex-related venom variation in V. seoanei, highlighting the need for larger studies that combine individually resolved quantitative proteomics with dietary, ecological, and functional data.
Corga, F., Lakušić, M., Vitorino, R., & Martínez-Freiría, F. (2026). Venom composition of the Iberian adder (Vipera seoanei) from northern Portugal reveals limited sex and size variation. Toxicon, 109320. https://doi.org/10.1016/j.toxicon.2026.109320