Venom-injecting fangs evolved independently in vipers and cobras

Venom-injecting fangs evolved independently in vipers and cobras

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Venom fangs evolved separately in several species of modern snakes, according to a new study led by former University of Alberta students and post-doctoral fellows in an international collaboration.

“This research provides a textbook example of convergent evolution, in which two or more lineages with a common ancestor tweak that ancestral body plan in similar ways independently to adapt to a similar challenge,” said lead author Alessandro Palci, who earned his PhD at the U of A and is now a post-doctoral fellow at Flinders University. “So we end up with vipers and cobras, two snake lineages separated by about 40 million years, that both evolve large fangs at the front of their mouth.”

Illustration of the skull of a taipan, one of the world’s most venomous snakes, and sections through its left fang showing the relationship between the venom groove and infoldings at the base of the tooth. Image credit: Alessandro Palci

Palci led the research while holding a visiting professor award in the U of A’s Faculty of Science in 2020.

Considered one of the most successful groups of vertebrates, snakes are a source of great interest for the scientific community—in particular, the factors that contribute to their evolutionary success.

The venomous teeth of modern snakes share several common characteristics, including a venom-delivering tube or groove made up of a type of tissue called plicidentine. Plicidentine is widespread among snakes and is key to understanding how snakes could repeatedly evolve their fangs.

“A snake’s venom fang is an iconic example because it’s a tooth that’s been modified into a venom-injecting syringe,” said co-author Aaron LeBlanc, a former Killam post-doctoral fellow in the Faculty of Science who earned his MSc at the U of A. LeBlanc is now a Marie Curie post-doctoral fellow at King’s College London.

“Our closer look into the development and evolution of snake teeth tells us how this might have happened through gradual, piecemeal changes,” LeBlanc said.

“It reveals how mutations and subtle changes in tooth shape and size can slowly modify a tooth from a grasping and puncturing structure into a new tooth type that injects venom.”

LeBlanc and Palci undertook the research while they worked with professor Michael Caldwell in the U of A’s Department of Biological Sciences.

“Alessandro and Aaron recognized that the evolutionary novelty of venom fangs—the tubes or grooves to deliver venom—evolved numerous times within different lineages of snakes,” said Caldwell. “This novel venom groove or tube is nothing more than an elongated dentine wrinkle, a plicidentinous fold, that closes up on itself—that amazes me.”

Source: University of Alberta




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