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

A study on spitting cobras, published in Science reveals how a combination of venom components evolved to create an instantly painful venom, not once, but three times.

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

Contrary to the theory that venoms are primarily adapted to allow snakes to kill their prey, by spitting cobras, a venom that causes instant pain and a delivery system that allows the snake to spray the venom from a distance 2.5 meters towards the eyes of anything that gets too close, suggests a defense mechanism, rather than hunting weapons.

Dr Wolfgang Wüster, of the School of Natural Sciences at Bangor University, co-investigator on the international research project, explains: “Here is another strong piece of evidence to illustrate that similar evolutionary challenges often generate the same solutions. Although we have studied three different cobra groups, which evolved in different places and at different times of evolution, each developed the same defensive mechanisms in the face of a threat.

All cobras have components of venom that cause tissue destruction called cytotoxins. But while spitting cobras, the addition of another group of toxins, phospholipases A2, created a synergistic effect, resulting in an instantly painful venom, which can quickly deter and even blind an attacker.

Understanding to what extent evolution is unpredictable, almost random or predictable is a major question in biology. This is a remarkable example of the same problem leading to the same solution evolving multiple times – i.e. predictable evolution

Oddly, going back through evolutionary lineages, the team also found that the changes were occurring in all three different geographic locations around the same time that the first humans appeared in the fossil record in those areas.

Dr Wüster adds: “Many primates attack snakes with sticks and stones. The arrival of bipedal hominids, both hands free for mischief, may have been just the kind of selection pressure that favored the defense. at long distance by sputum and a specially adapted defense venom.

The idea that the first humans, millions of years ago, may have caused the evolution of sputum in cobras highlights how closely our origins were linked to the larger ecosystems of Africa and Asia. at the time “

Masters students at Bangor University studying the only Zoology with Herpetology course in the UK had the opportunity to contribute to this international research project. The students were responsible for generating DNA sequences to generate the phylogeny, or evolutionary family tree, of cobras, which allowed the study to trace the evolution of venom adaptations.

Anthony Plettenberg Laing, originally from Cambridge and now based 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 has often been called the herpetological capital of the United Kingdom and was the only institute in the United Kingdom to offer a specific herpetology course. It has a team of world-renowned researchers specializing in this field. So I knew that coming to Bangor was going to incubate my passion and help me grow and flourish there, allowing me to get deeply involved in the field of herpetology. “

“During my studies at Bangor, I worked on various exciting projects with Dr Wolfgang Wüster and his colleagues, including research on the iconic African and Asian cobras of the genus Naja. My work included sequencing a number of genes and creating phylogenetic trees to understand when and why different species split up. To be the author of such a prestigious and impactful study Science is an incredible honor and a real 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 have been able to learn so much in many different areas 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. Without knowing it at the time, my research there contributed to larger studies and had a bigger impact than I could have predicted. ”