Discovery is part of NSF's Assembling the Tree of Life initiative
In the process of piecing together the evolutionary history of snakes and lizards, biologists have discovered that nearly every living species of snake came from a bizarre group of small, blind, burrowing snakes.
A new study suggests that snake ancestors were likely small, lived underground, and fed mainly on termites and ant larva.
The thousands of advanced snakes living today adapted to surface habitats and radiated throughout temperate and tropical forests, dry savannahs and deserts, and even marine environments.
The study caps seven years of research on the “Deep Scaly” branch of the National Science Foundation-funded “Assembling the Tree of Life” initiative, and was headed by biologists at San Diego State University, Brigham Young University, Stony Brook University, University of Texas-Austin, Yale and the Field Museum of Natural History.
“It really was surprising to find that the root of most modern snakes goes back to that one group,” said Jack W. Sites, Jr., BYU biology professor and study co-author. “Whether they live in trees or the ocean, whether they are constrictors or venomous snakes, whether they are 25-inch garter snakes or 25-foot anacondas, they all have the same small, semi-blind ancestor.”
Details of the newly reconstructed snake-and-lizard tree of life appear in a newly published issue of the academic journal Biology Letters.
The study used the largest molecular dataset ever assembled to address issues about the evolutionary history of lizards and snakes. The data included sequences from 44 genes, resolved for 161 species representing all recognized families and major groups of living snakes and lizards.
Using the DNA sequence data, researchers were able to tie nearly all living snakes back to scolecophidians: tiny snakes with small, rounded heads, small eyes, and small mouths. Scolecophidians do not have the jaw flexibility that most advanced snakes do, meaning they cannot expand their mouths to swallow larger prey.
Lead author John J. Wiens, a professor of ecology and evolution at Stony Brook University, suggests there are still traces of subterranean ancestry in the anatomy of snakes that live on land surfaces.
“For example, no matter where they live, snakes have an elongate body and a relatively short tail, and outside of snakes, this body shape is only found in lizards that live underground,” Wiens said in a press release. “Snakes have kept this same basic body shape as they have evolved to invade nearly every habitat on the planet.”
Assembling the Tree of Life is a massive research initiative with the goal to reconstruct the evolutionary origins of the planet’s living creatures. Sites says the extraordinary effort is evolutionary biologists’ equivalent to putting a man on the moon.
For the last decade, researchers across the nation have been piecing together the evolutionary history of everything from fungi to beetles to large mammals. BYU’s Department of Biology has received five AToL grants during that time, making BYU one of the most awarded AToL institutions in the country.
Sites was invited to join the “Deep Scaly” team that began work in 2004 to resolve controversies in the branch of the tree dealing with snakes and lizards. After seven years of research, his team has met every goal in their original grant-winning proposal.
“We’ve been able to reconstruct the trunk and the major limbs of the tree of life for snakes and lizards,” Sites said. “Now every master’s student, doctorate student and professor out there has the foundation for the smaller branches of that tree.”
The portion of NSF funding that came to BYU supported seven years of work for Sites, 25 undergraduate students, and multiple graduate and post-doctoral researchers, though a majority of the undergrads were supported with BYU mentoring grants. More than 30 student papers were published as spin-off projects as well.
