An arachnid’s guide to being an ant: Morphological and behavioural mimicry in ant-mimicking spiders

Batesian mimicry imposes several challenges to mimics and evokes adaptations in multiple sensory modalities. Myrmecomorphy, morphological and behavioral resemblance to ants, is seen in over 2000 arthropod species. Ant-like resemblance is observed in at least 13 spider families despite spiders having a distinct body plan compared to ants. Quantifying the extent to which spiders’ shape, size, and behavior resemble model ants will allow us to comprehend the evolutionary pressures that have facilitated myrmecomorphy. Myrmaplata plataleoides are thought to closely resemble weaver ants, Oecophylla smaragdina. In this study, we quantify the speed of movement of model, mimic, and non-mimetic jumping spiders. We use traditional and geometric morphometrics to quantify traits such as foreleg and hindleg size and body shape between the model ant, mimic, and non-mimics. Our results suggest that while the mimics closely resemble the model ants in speed of movement, they occupy an intermediate morphological space compared to the model ants and non-mimics. We suggest that ant-mimicking spiders are better at mimicking ants’ locomotory movement than morphology and overall body shape. Our study provides a framework to understand the multimodal nature of mimicry and helps discern the relative contributions of such traits that drive mimetic accuracy in ant-mimicking spiders.贝茨拟态（Batesian mimicry）会给拟态者带来多重挑战，并促使其演化出多感官模态的适应性特征。蚁形拟态（Myrmecomorphy），即形态与行为上对蚂蚁的拟态，已在超过2000种节肢动物中被观测到。尽管蜘蛛与蚂蚁的躯体构型（body plan）差异显著，但至少有13个蜘蛛科类群展现出类蚁外形特征。量化蜘蛛的形态、体型与行为和作为模型的蚂蚁之间的相似程度，将帮助我们理解推动蚁形拟态演化的进化压力。扁形蚁蛛（Myrmaplata plataleoides）被认为与织叶蚁（Oecophylla smaragdina）高度相似。本研究中，我们对作为模型的蚂蚁、拟态蜘蛛与非拟态跳蛛的移动速度进行了量化分析；同时利用传统形态测量学与几何形态测量学（traditional and geometric morphometrics），量化了模型蚂蚁、拟态蜘蛛与非拟态蜘蛛的前足、后足尺寸及躯体形态等性状。研究结果显示，尽管拟态蜘蛛在移动速度上与模型蚂蚁高度相似，但相较于模型蚂蚁与非拟态蜘蛛，它们的形态学特征处于中间区间。我们认为，拟蚁蜘蛛对蚂蚁运动行为的拟态效果优于其对形态与整体躯体构型的拟态。本研究为理解拟态的多模态本质提供了分析框架，并有助于剖析驱动拟蚁蜘蛛拟态精度的各类性状的相对贡献。