BYU Today

Scaly Reptile Genealogy


BYU biologist Jack W. Sites Jr. has been tapped to join a project the National Science Foundation (NSF) likens to the missions that placed a man on the moon and that deciphered the human genome.

Jack Sites

Jack Sites and his students will collaborate with other scientists to trace the genetic histories of 150 species of scaly creatures. Photo by Bradley Slade.

The NSF’s “Assembling the Tree of Life” project aims to discover the evolutionary history of all life on Earth. Sites, a professor of integrative biology, is part of the team that recently earned a $2.4 million grant to tackle the branch that includes scaly reptiles like lizards and snakes.

With more than 7,000 species, this group, known as squamates (which derives from the word for “scaly”), is second only to birds as the world’s largest group of terrestrial vertebrates. Scientists are still struggling to understand the origin of the legless lizards we call snakes and resolve other fundamental biological questions regarding these animals. Determining genetic relationships will help guide conservation efforts and improve medicine, especially related to treating snakebites, a common cause of death in developing nations.

“I’m always interested in tackling the big questions,” says Sites. “The Tree of Life project is about as big as it gets in biology.”

Sites and his students will work with a network of six other institutions from Australia to New York to identify key marker genes in about 150 representative species and analyze and compare DNA sequences. The group will also consider information inferred from anatomical characteristics of extinct species preserved as fossils. That work will be led by Jacques Gauthier, a professor of geology at Yale, which is a subcontractor to the BYU team.

“We’re doing this because we think a scientist can’t discover something more fundamental about an organism than its genealogical connections,” Gauthier says. “I feel especially privileged for the opportunity to explore such fundamental issues in the history of life with a scientist of Jack Sites’ caliber.”

“Reptiles give us a fascinating window into the capabilities of living things, stretching our understanding of what is possible,” Sites says, ticking off a list of biological stunts his favorite subjects can perform, including the following:

• Seventy species of lizards reproduce asexually (no males exist).

• The sex of some species is determined by nest temperature during incubation.

• Other lizards can freeze as solid as a block of ice and survive, relying on a chemical “antifreeze” produced by their livers to keep their heart and brain barely functioning.

• Large snakes can go without food for six to 12 months, then crank up their digestive systems to process one meal that is 80 percent of their body weight.

Sites hopes his NSF project, dubbed “Deep Scaly” for its in-depth look at squamates, will unveil some of the genetic basis behind the development of these characteristics as well as provide clues to how all organisms develop and change.

In the process his students will gain experience in the lab and from collaborating with top scientists in their field. Each year the multi-institutional group will gather at Chicago’s Field Museum for Natural History—another team member—to compare notes and plan strategy.

“I’m looking forward to collaborating with Dr. Sites, an internationally recognized researcher in herpetology, phylogenetics (genealogy) and biodiversity,” says Maureen Kearney, assistant curator in the field museum’s division of amphibians and reptiles. “His expertise in the molecular biology of lizards and snakes will bring outstanding depth to the genomic aspect of the research project.”