Data from: Mandible-powered escape jumps in trap-jaw ants increase survival rates during predator-prey encounters

Animals use a variety of escape mechanisms to increase the probability of surviving predatory attacks. Antipredator defenses can be elaborate, making their evolutionary origin unclear. Trap-jaw ants are known for their rapid and powerful predatory mandible strikes, and some species have been observed to direct those strikes at the substrate, thereby launching themselves into the air away from a potential threat. This potential escape mechanism has never been examined in a natural context. We studied the use of mandible-powered jumping in Odontomachus brunneus during their interactions with a common ant predator: pit-building antlions. We observed that while trap-jaw ant workers escaped from antlion pits by running in about half of interactions, in 15% of interactions they escaped by mandible-powered jumping. To test whether escape jumps improved individual survival, we experimentally prevented workers from jumping and measured their escape rate. Workers with unrestrained mandibles escaped from antlion pits significantly more frequently than workers with restrained mandibles. Our results indicate that some trap-jaw ant species can use mandible-powered jumps to escape from common predators. These results also provide a charismatic example of evolutionary co-option, where a trait that evolved for one function (predation) has been co-opted for another (defense).

动物演化出多种逃逸策略以提升捕食攻击下的存活概率。反捕食防御机制往往结构复杂，其演化起源常难以厘清。陷阱颚蚁（Trap-jaw ants）以快速且强劲的捕食性颚部钳击为标志性特征，部分物种甚至会将这类钳击作用于基底底物，借此腾空跃起以脱离潜在威胁。这种潜在的逃逸方式此前从未在自然情境下得到研究。我们针对棕异颚刺蚁（Odontomachus brunneus）在与一类常见蚁类捕食者——造坑蚁狮（pit-building antlions）——的互动过程中借助颚部动力实现跳跃的行为展开了研究。观测结果显示：在约半数的互动场景中，陷阱颚蚁工蚁通过爬行脱离蚁狮陷阱；另有15%的互动场景里，它们借助颚部动力驱动的跳跃完成逃逸。为验证逃逸跳跃是否能提升个体存活率，我们通过实验限制工蚁的跳跃能力并统计其逃逸成功率。结果表明，颚部活动不受限的工蚁脱离蚁狮陷阱的成功率显著高于颚部被限制的工蚁。本研究结果显示，部分陷阱颚蚁物种可借助颚部动力驱动的跳跃脱离常见捕食者的捕猎。该发现同时为演化共招募（evolutionary co-option）现象提供了极具说服力的案例：原本为捕食功能演化出的性状，如今被招募用于防御功能。