Report

Convergent evolution of pain-inducing defensive venom components in spitting cobras

See allHide authors and affiliations

Science  22 Jan 2021:
Vol. 371, Issue 6527, pp. 386-390
DOI: 10.1126/science.abb9303

You are currently viewing the abstract.

View Full Text

Log in to view the full text

Log in through your institution

Log in through your institution

From offense to defense

Venom in snakes is largely used to subdue and/or kill prey, and most venoms have clear actions that facilitate death or paralysis. In one group of snakes, however, venom has evolved and shifted from predation to protection. Specifically, in three different lineages of “spitting” snakes, venom is used to deter predators. Kazandjian et al. show that similar adaptions have occurred within these lineages that transform cytotoxic components into a mixture that acts on mammalian sensory neurons and causes pain. The authors argue that increased predation on these lineages led to similar shifts in venom function.

Science, this issue p. 386

Abstract

Convergent evolution provides insights into the selective drivers underlying evolutionary change. Snake venoms, with a direct genetic basis and clearly defined functional phenotype, provide a model system for exploring the repeated evolution of adaptations. While snakes use venom primarily for predation, and venom composition often reflects diet specificity, three lineages of cobras have independently evolved the ability to spit venom at adversaries. Using gene, protein, and functional analyses, we show that the three spitting lineages possess venoms characterized by an up-regulation of phospholipase A2 (PLA2) toxins, which potentiate the action of preexisting venom cytotoxins to activate mammalian sensory neurons and cause enhanced pain. These repeated independent changes provide a fascinating example of convergent evolution across multiple phenotypic levels driven by selection for defense.

View Full Text

Stay Connected to Science