Arboreal ants must navigate variably sized and inclined linear structures across a range of substrate roughness when foraging tens of meters above the ground. To achieve this, arboreal ants use specialized adhesive pads and claws to maintain effective attachment to canopy substrates. Here, we explored the effect of substrate structure, including small and large-scale substrate roughness, substrate diameter, and substrate orientation (inclination), on adhesion and running speed of workers of one common, intermediately-sized, arboreal ant species. Normal (orthogonal) and shear (parallel) adhesive performance varied on sandpaper and natural leaf substrates, particularly at small size scales, but running speed on these substrates remained relatively constant. Running speed also varied minimally when running up and down inclined substrates, except when the substrate was positioned completely vertical. On vertical surfaces, ants ran significantly faster down than up. Ant running speed was slower on relatively narrow substrates. The results of this study show that variation in the physical properties of tree surfaces differentially affects arboreal ant adhesive and locomotor performance. Specifically, locomotor performance was much more robust to surface roughness than was adhesive performance. The results provide a basis for understanding how performance correlates of functional morphology contribute to determining local ant distributions and foraging decisions in the tropical rainforest canopy.

中文翻译：

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热带树栖蚂蚁 (Cephalotes atratus) 在粗糙、狭窄和倾斜基材上的附着力和奔跑速度

树栖蚂蚁在离地面几十米的地方觅食时，必须在各种不同大小和倾斜的线性结构上穿行，跨越一定范围的基底粗糙度。为了实现这一点，树栖蚂蚁使用专门的粘合垫和爪子来保持对树冠基底的有效附着。在这里，我们探索了基材结构，包括小型和大型基材粗糙度、基材直径和基材方向（倾斜度），对一种常见、中等大小的树栖蚂蚁物种的附着力和奔跑速度的影响。正常（正交）和剪切（平行）粘合性能在砂纸和天然叶基材上各不相同，特别是在小尺寸范围内，但在这些基材上的运行速度保持相对恒定。上下倾斜的基材运行时，运行速度的变化也很小，除非基板完全垂直放置。在垂直表面上，蚂蚁向下跑的速度明显快于向上跑。蚂蚁在相对较窄的基板上运行速度较慢。这项研究的结果表明，树木表面物理特性的变化对树栖蚂蚁的粘附和运动性能有不同的影响。具体而言，运动性能对表面粗糙度的影响比粘附性能强得多。结果为理解功能形态的性能相关性如何有助于确定热带雨林冠层中的局部蚂蚁分布和觅食决策提供了基础。这项研究的结果表明，树木表面物理特性的变化对树栖蚂蚁的粘附和运动性能有不同的影响。具体而言，运动性能对表面粗糙度的影响比粘附性能强得多。结果为理解功能形态的性能相关性如何有助于确定热带雨林冠层中的局部蚂蚁分布和觅食决策提供了基础。这项研究的结果表明，树木表面物理特性的变化对树栖蚂蚁的粘附和运动性能有不同的影响。具体而言，运动性能对表面粗糙度的影响比粘附性能强得多。结果为理解功能形态的性能相关性如何有助于确定热带雨林冠层中的局部蚂蚁分布和觅食决策提供了基础。