Credit: The Trustees of the Natural History Museum, London and Callum Mair
Researchers from LSTM s Centre for Snakebite Research and Interventions (CSRI) have led an international team investigating the evolutionary origins of a novel defensive trait by snakes - venom spitting - and demonstrated that defensive selection pressures can influence venom composition in snakes in a repeatable manner.
In a paper published in the journal
Science, the team, which includes authors from the UK, USA, Australia, the Netherlands, Spain, Norway, Brazil and Costa Rica, provide the first example of snake venom evolution being demonstrated to be associated with a role in defence, rather than the wide consensus that venom evolution is driven solely for prey capturing-ability.
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While previous studies suggest snake venom differences are largely driven by variation in diet, a new analysis in three lineages of spitting cobra points to a different mechanism - the need to defend - as the driver of these pain-inducing venoms unique traits. Spitting cobras highlight how similar selection pressures.can drive convergence at molecular, morphological,
behavioral, and functional levels, say the authors. For the vast majority of snakes, venom is primarily used for predation - to disable or dispatch a would-be meal. The evolution of venom spitting in cobras, by contrast, plays no role in prey capture. Rather, it targets specific sensory tissues and is the only long-distance, injurious defensive adaptation among almost 4,000 species of snakes. Unexpectedly, three lineages of venomous snakes in the family Elapidae have independently evolved the ability to spit their venom over several meters and into the eyes of a perceived threat, causing pain as a me
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Online News Editor David Grimm joins host Sarah Crespi to discuss a controversial new paper that estimates how many rodents are used in research in the United States each year. Though there is no official number, the paper suggests there might be more than 100 million rats and mice housed in research facilities in the country doubling or even tripling some earlier estimates.
Sarah also chats with Taline Kazandjian, a postdoctoral research associate at the Centre for Snakebite Research & Interventions in Liverpool, U.K., about how the venom from spitting cobras has evolved to cause maximum pain and why these snakes might have developed the same defense mechanism three different times.