Extensive Duplication and Diversification in Micrurus Three-Finger Toxins

Dashevsky, Daniel

School of Biological Sciences

University of Queensland

Brisbane, QLD, Australia

Fry, Bryan G.

School of Biological Sciences

University of Queensland

Brisbane, QLD, Australia

Coral snakes, most notably the genus Micrurus, are the only representatives of elapid snakes in the Americas. Elapid venoms are generally known for their potent neurotoxicity which is usually caused by Three-Finger Toxin (3FTx) proteins. These toxins have evolved a wide array of functions that have been characterized from the venom of other elapids. We examine publicly available sequences from Micrurus 3FTx to show that they form several monophyletic clades that diverged as early in the 3FTx phylogenetic tree as other major functional divisions. We also analyze the patterns of selection on these Micrurus toxins and find that some clades have been diversifying at a rapid rate. This suggests that Micrurus venoms may contain a previously underappreciated functional diversity that has implications for the clinical outcomes of bite victims, the evolution and ecology of the genus, as well as the potential for bio-discovery efforts focusing on these toxins.