Journal of Molecular Evolution

, Volume 60, Issue 1, pp 81–89 | Cite as

Eggs-Only Diet: Its Implications for the Toxin Profile Changes and Ecology of the Marbled Sea Snake (Aipysurus eydouxii)

  • Min Li
  • B.G. Fry
  • R. Manjunatha KiniEmail author


Studies so far have correlated the variation in the composition of snake venoms with the target prey population and snake’s diet. Here we present the first example of an alternative evolutionary link between venom composition and dietary adaptation of snakes. We describe a dinucleotide deletion in the only three finger toxin gene expressed in the sea snake Aipysurus eydouxii (Marbled Sea Snake) venom and how it may have been the result of a significant change in dietary habits. The deletion leads to a frame shift and truncation with an accompanying loss of neurotoxicity. Due to the remarkable streamlining of sea snake venoms, a mutation of a single toxin can have dramatic effects on the whole venom, in this case likely explaining the 50- to 100-fold decrease in venom toxicity in comparison to that of other species in the same genus. This is a secondary result of the adaptation of A. eydouxii to a new dietary habit — feeding exclusively on fish eggs and, thus, the snake no longer using its venom for prey capture. This was parallel to greatly atrophied venom glands and loss of effective fangs. It is interesting to note that a potent venom was not maintained for use in defense, thus reinforcing that the primary use of snake venom is for prey capture.


Sea snake Venom gland Pseudogene Three-finger toxin Neurotoxin Aipysurus eydouxii 



This work was supported by grants from the Australian Geographic Society, Australia & Pacific Science Foundation, Australian Research Council, Biomedical Research Council, Agency for Science and Technology Research in Singapore, Maritime Union of Australia, and University of Melbourne. We would also like to thank the Queensland Environmental Protection Agency for the granting of scientific permits to collect sea snakes. We thank Drs. Prakash Kumar and Navjyot Sodhi for their critical reading of the manuscript. We are deeply grateful to Dave Donald for all his help with the sea snake field research.


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Copyright information

© Springer Science+Business Media, Inc. 2005

Authors and Affiliations

  1. 1.Department of Biological Science, Faculty of ScienceNational University of SingaporeSingapore
  2. 2.Australian Venom Research Unit, Department of Pharmacology, School of MedicineUniversity of MelbourneParkvilleAustralia
  3. 3.Population and Evolutionary Genetics UnitMuseum VictoriaMelbourneAustralia
  4. 4.Department of Biochemistry and Molecular BiophysicsVirginia Commonwealth University, Medical College of VirginiaRichmondUSA

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