Fry said the caecilians were able to achieve this never-before-seen venom resistance by deploying three different kinds of biological methods. "These were the ones that repopulated the earth after the elapid snake plague."ĭr. "It's an extraordinary signal for response to such severe selection pressure, where the survivors of the onslaught were those who were a bit less sensitive to the venom and some had mutations that made them completely immune. "A particularly interesting validation of the theory was that the caecilians on the Seychelles islands were not resistant to snake venom, which is consistent with elapid snakes never reaching those islands. "We showed that resistance to elapid snake venom neurotoxins has evolved on at least 15 times-which is absolutely without precedent," Mr. Lead author, Marco Mancuso from Vrije Universiteit Brussel's Amphibian Evolution Lab, said the study involved using tissue collections to sequence a part of the neuromuscular receptor in caecilians bound by toxins in snake venom. The team studied caecilian species from across all known families across the globe, including species in the Seychelles islands never reached by elapid snakes. "The caecilian's ability to persevere and evolve despite these pressures is like a movie-like the survivors of Judgment Day fighting back by changing the chemical landscape." "It would have been absolute carnage to the point where elapids were basically grazing on caecilians, contributing to the rapid spread of elapid snakes across Africa, Asia, and the Americas. "Despite being quite slippery, caecilians are worm-like in their locomotion and speed and were incredibly easy prey to cobras and other snakes, which used their fangs to kill them and eat them later. "In this case, the key predatory pressure was the rise of the elapid snakes, such as cobras and coral snakes, characterized by the evolution of a new way of delivering venom via their hollow, fixed, syringe-like fangs. "Our research provides a textbook example of how a single predatory pressure can trigger an evolutionary cascade where the same way of fighting back arises independently multiple times in a species' different lineages," Dr. The University of Queensland's Associate Professor Bryan Fry led the study, which he said provides a solid model for the fundamental evolutionary concept of predator-prey interactions.
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