A developmental shift in venom toxin expression underpins a major prey switch in Australian Brown Snakes

ABSTRACT: Many animals undergo morphological, physiological, and behavioral changes over the course of their life history. It has been proposed that some of these developmental changes evolve in concert with shifts in ecology, but there are relatively few clear examples, and identifying the underlying molecular mechanisms is challenging. Australian Brown Snakes (Pseudonaja spp.), one of Australia's most venomous snakes, may provide such an example, as previous work has shown that these species undergo a dietary shift from reptiles to mammals, accompanied by differences in venom activity. Here, we show that the venom composition of adult Brown Snakes is distinguished by the collective expression of four procoagulant toxin families, which are not expressed in juvenile life stages. We also find that the developmental timing of the onset of procoagulant toxin expression correlates with a functional shift in venom activity to one that disrupts mammalian prey’s blood-clotting system. We further demonstrate that these shifts in toxin expression and procoagulant activity, do not occur in the smallest Brown Snake species that has evolved to be a permanent lizard-eating specialist. Collectively, we show that the coordinated shift in toxin expression mediates a major venom change in Australian Brown Snakes, from a neurotoxin-dominated venom in juveniles, used for capturing small lizards, to a procoagulant venom in adults, used for subduing mammals. Our findings therefore provide a compelling example of how animals adapt to ecological challenges that they face at different life stages.

INSTRUMENT(S):

ORGANISM(S): Pseudonaja Textilis Pseudonaja Modesta Pseudonaja Aspidorhyncha

TISSUE(S): Venom

SUBMITTER: Cara Smith  

LAB HEAD: Anthony Saviola

PROVIDER: PXD063001 | Pride | 2026-04-13

REPOSITORIES: Pride