Molecular Ecology and Fisheries Genetics Laboratory, School of Natural Sciences, Bangor University, Bangor LL57 2UW, UK.
Department of Biosciences, College of Science, Swansea University, Swansea SA2 8PP, UK.
Toxins (Basel). 2020 Mar 22;12(3):201. doi: 10.3390/toxins12030201.
Animals use venoms for multiple purposes, most prominently for prey acquisition and self-defense. In snakes, venom composition often evolves as a result of selection for optimization for local diet. However, whether selection for a defensive function has also played a role in driving the evolution of venom composition has remained largely unstudied. Here, we use an online survey of snakebite victims to test a key prediction of a defensive function, that envenoming should result in the rapid onset of severe pain. From the analysis of 584 snakebite reports, involving 192 species of venomous snake, we find that the vast majority of bites do not result in severe early pain. Phylogenetic comparative analysis shows that where early pain after a bite evolves, it is often lost rapidly. Our results, therefore, do not support the hypothesis that natural selection for antipredator defense played an important role in the origin of venom or front-fanged delivery systems in general, although there may be intriguing exceptions to this rule.
动物使用毒液有多种用途，最主要的是用于获取猎物和自我防御。在蛇类中，毒液的组成通常是由于对当地食物的优化选择而进化的。然而，选择防御功能是否也在驱动毒液组成的进化方面发挥了作用，在很大程度上仍未得到研究。在这里，我们使用蛇咬伤受害者的在线调查来检验防御功能的一个关键预测，即中毒应该会导致剧烈疼痛的迅速发作。从对涉及 192 种毒蛇的 584 个蛇咬伤报告的分析中，我们发现绝大多数咬伤不会导致早期剧烈疼痛。系统发育比较分析表明，在咬伤后出现早期疼痛的地方，这种疼痛通常会迅速消失。因此，我们的结果并不支持这样的假设，即自然选择的防御捕食者在毒液或前齿型输送系统的起源中发挥了重要作用，尽管可能存在一些有趣的例外情况。
