A comprehensive analysis of the genetic relationship between snakes, lizards, and other reptiles has led to a new phylogenetic tree for this group of animals, researchers have reported.
These findings are hoped to rewrite the evolutionary history of reptiles and answer the question: when and how did certain snake species develop venom?
The evolution of venom systems was previously believed to be influenced by radiation in evolved snake species. In contrast, the venom system of lizards was thought to be limited to two species and evolved independently from that of snakes.
However, in this new study, scientists from Australia, Switzerland, and the United States have indicated that the common ancestor of snakes and lizards possessed a venom system, and when snakes began to evolve around 100 million years ago, their venom genes were already 100 million years old.
The scientists compared nine genes across 19 species of snakes and lizards. They found that snakes are closely related to a group of lizards that includes the blue-tongued skink, Indonesian lizard, bearded dragon, and Gila monster. Only one of these species is venomous. Distant relatives of lizards, such as chameleons and short-legged skinks, do not possess venom genes.
“We used to think that venom was a result of recent evolutionary processes, but this study shows that this evolution took place very early in the history of reptiles, around 200 million years ago, when dinosaurs were just beginning to evolve,” said Blair Hedges, a professor at Pennsylvania State University and a member of the research team.
The researchers selected and analyzed the largest genetic data set collected from scaly reptiles. The resulting phylogenetic tree revealed several surprising relationships within the scientific community.
“This research provides a new perspective on the evolution of the venom system in scaly reptiles and paves the way for biomedical and pharmaceutical research utilizing venom proteins that have yet to be explored,” the scientists stated.
This study may also assist scientists in identifying fossils of more species as it provides additional information about the geological periods in which these fossils may be found.
T.VY (Xinhua)
