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).

动物演化出多样的逃逸策略，以提升遭遇捕食者攻击时的存活概率。反捕食防御机制往往结构精巧复杂，其演化起源至今尚不明确。陷阱颚蚁（trap-jaw ants）以快速且强劲的捕食性上颚咬合动作闻名，已有观测发现部分物种会将这类咬合动作施加于基底表面，借此将自身弹射入空中以脱离潜在威胁。但这类潜在的逃逸机制从未在自然环境中得到系统性研究。本研究针对棕齿猛蚁（Odontomachus brunneus）在与常见蚁类捕食者——筑坑蚁狮（pit-building antlions）——的互动过程中，利用上颚驱动跳跃的行为展开了探究。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逃离蚁狮陷阱；而在15%的互动场景中，它们借助上颚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概率，我们通过实验手段限制工蚁的跳跃能力，并统计其逃逸成功率。上颚活动不受限的工蚁，其逃离蚁狮陷阱的成功率显著高于上颚被限制的工蚁。本研究结果表明，部分陷阱颚蚁物种可借助上颚驱动的跳跃行为，脱离常见捕食者的捕猎。该结果同时为演化共募（evolutionary co-option）现象提供了一个极具代表性的实例：原本为捕食功能演化而来的性状，被借用于防御这一全新功能。