Abstract:
Intra-specific venom variation has the potential to provide important insights into the
evolution of snake venom, but remains a relatively neglected aspect of snake venom studies.
We investigated the venom from 13 individual coastal taipans Oxyuranus scutellatus from four
localities on the north-east coast of Australia, spanning a distance of 2000 km. The intra-specific
variation in taipan venom was considerably less than the inter-specific variation between it and the
other Australian elapids to which it was compared. The electrophoretic venom profile of O. scutellatus
was visually different to six other genera of Australian elapids, but not to its congener inland taipan
O. microlepidotus. There was minimal geographical variation in taipan venom, as the intra-population
variation exceeded the inter-population variation for enzymatic activity, procoagulant activity, and the
abundance of neurotoxins. The pre-synaptic neurotoxin (taipoxin) was more abundant than the
post-synaptic neurotoxins (3FTx), with a median of 11.0% (interquartile range (IQR): 9.7% to 18.3%;
range: 6.7% to 23.6%) vs. a median of 3.4% (IQR: 0.4% to 6.7%; range: 0% to 8.1%). Three taipan
individuals almost completely lacked post-synaptic neurotoxins, which was not associated with
geography and occurred within two populations. We found no evidence of sexual dimorphism in
taipan venom. Our study provides a basis for evaluating the significance of intra-specific venom
variation within a phylogenetic context by comparing it to the inter-specific and inter-generic
variation. The considerable intra-population variation we observed supports the use of several
unpooled individuals from each population when making inter-specific comparisons.
