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

6 páginas, 3 figuras.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.This work was funded from a studentship supported by Elizabeth Artin Kazandjian to T.D.K.; grant PE 2600/1 from the German Research Foundation (DFG) to D.P.; grant OPUS 1354156 from the U.S. National Science Foundation to H.W.G.; grants FAPESP 2017/18922-2 and 2019/05026-4 from the São Paulo Research Foundation to R.R.d.S.; grants RPG-2012-627 and RFG-10193 from the Leverhulme Trust to R.A.H. and W.W.; grant MR/L01839X/1 from the U.K. Medical Research Council to J.M.G., R.A.H., J.J.C., and N.R.C.; Career Development Fellowships APP1162503 and DP190103787 from the Australian National Health and Medical Research Council to I.V.; fellowship DE160101142 and grant DP160104025 from the Australian Research Council, and fellowship FRIPRO-YRT #287462 from the Research Council of Norway to E.A.B.U.; and a Sir Henry Dale Fellowship (200517/Z/16/Z) jointly funded by the Wellcome Trust and Royal Society to N.R.C.Peer reviewe