Spitting cobra venom reveals how evolution often finds the same answer to a common problem

A study of spitting cobras, published in Science reveals how a combination of poison components evolved to create an immediate painful poison, not once, but on three separate occasions.

This is the first clear example of snake venom being developed for defense, and provides a remarkable example of converging evolution, or how natural selection can cause the same solution to a problem to develop multiple times.

Contrary to the theory that poisons are mainly adapted to enable snakes to kill prey, in spitting cobras, a poison that causes immediate pain, and a delivery system that allows the snake to remove the venom to a distance of up to 2, 5 meters to the eyes can spray from anything that comes too close, indicating a defense mechanism rather than hunting weapons.

Dr. Wolfgang Wüster, from Bangor University’s School of Natural Sciences, co-researcher of the international research project, explains: ‘Here is further strong evidence to illustrate that similar evolutionary challenges often generate the same solutions. Although we studied three different studies of cobra groups, which evolved in different places and in different evolutionary periods, each developed the same defense mechanisms in the face of a threat.

All cobras have toxic components that cause tissue destruction, called cytotoxins. But when spitting cobras, the addition of another group of toxins, phospholipases A2, results in a synergistic effect, which results in an immediate painful poison, which can quickly deter an attacker and even blind him.

Understanding the extent to which evolution is unpredictable, almost random, or predictable is an important question in biology. This is a remarkable example of the same problem that has led to the evolution of the same solution several times – that is, predictable evolution. “

Strikingly, by working back through evolutionary generations, the team also found that the changes took place in the three different geographical locations, about the same time as early humans appeared in the fossil record in those areas.

Dr. Wüster adds: “Many primates attack snakes with sticks and stones. The arrival of bipedal hominins, with both hands free from evil, was perhaps just the kind of selection pressure that favored long-range defense by spitting and a specially adapted defense.

The idea that early humans, millions of years ago, may have caused the evolution of spit in cobras, underscores how our origins at the time were very intertwined with the broader ecosystems of Africa and Asia. “

MSc students from Bangor University who are studying on the only zoology course in the UK in the UK have had the opportunity to contribute to this international research project. The students were responsible for generating DNA sequences to generate the phylogeny, or evolutionary tree, of cobras, through which the study could track the evolution of poison adaptations.

Anthony Plettenberg Laing, originally from Cambridge, and now in Berlin, Germany, is one of the authors. After his BSc in Zoology with Herpetology, he worked on this project for his MScRes and says:

“Bangor University is often referred to as the Herpetological Capital of the United Kingdom and was the only institute in the United Kingdom to offer a specific course in Herpetology. There is a team of world-renowned researchers specializing in this field. I therefore knew that going to Bangor would incubate my passion and help me grow and thrive there as well, allowing me to become strongly involved in the field of herpetology. ‘

“During my studies at Bangor, I worked on various exciting projects with Dr. Wolfgang Wüster and colleagues, including researching the iconic African and Asian cobras in the genus Naja. My work includes the sequencing of a number of genes. and the creation of phylogenetic trees created to understand when and why different species separated.To be a writer in such a prestigious and effective study in Science is an incredible honor and a true life achievement. ‘

Cara Hall from Barrow-in-Furness, Cumbria, came to study Zoology with animal behavior. She says: “The zoology degree was ideal for me. I was able to learn so much in different fields of research, gain a deeper understanding of biology and evolution in general and be actively involved in research to acquire essential laboratory skills for my future. at the time, my research there contributed to larger studies and had a greater impact than I could have expected. ‘