The Stabilizing Function of the Tail During Arboreal Quadrupedalism
The Stabilizing Function of the Tail During Arboreal Quadrupedalism
复制标题
树栖四足行走时尾部的稳定功能
DOI：
10.1093/icb/icab096
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发表时间：
2021
影响因子：
2.6
通讯作者：
Shapiro, Liza J
中科院分区：
文献类型：
--
作者：
Young, Jesse W;Chadwell, Brad A;Dunham, Noah T;McNamara, Allison;Phelps, Taylor;Hieronymus, Tobin;Shapiro, Liza J
在树木环境的狭窄和柔顺的支撑上运动本身就是不稳定的。先前的研究已经确定了树栖动物的许多形态和行为特征，这些特征被广泛认为是在不稳定的基质上促进稳定性的。对尾巴在保持平衡方面的作用研究得较少。然而，先前的解剖学研究发现，与陆地类群相比，树栖类群的尾巴通常比它们的体型长，并且先前的尾运动学和尾减少对焦点类群的影响的实验室研究广泛支持了尾巴在狭窄和移动的基质上保持平衡的功能重要的假设。在这组研究中，我们以两种方式扩展了这项工作。首先，我们使用松鼠猴（Saimiri boliviensis）的三维节段运动学和尾部惯性特性的实验室数据集来研究在狭窄支架上稳态运动时尾部角动量是如何调制的。在第二项研究中，我们使用野生长颈猴四足运动的定量数据集来研究自由放养的树栖动物如何根据基质变化调整尾巴运动，重点关注在先前的尾巴力学实验室研究中验证的运动学测量（包括所提供的实验室数据）。我们的实验室结果证明了这一点。玻利维亚人在狭窄的支撑物上显著增加平均尾翼角动量的大小和幅度，并主要通过调整尾翼的线速度和角速度来调节这种动量（而不是通过改变尾翼姿态本身）。在我们的第二项研究中，我们以这些发现为基础，展示了野生长颈犀牛通过延长尾巴和夸大尾巴位移来应对狭窄和移动基质的不稳定性，为这里和其他地方提出的尾巴力学的实验室研究提供了生态有效性。总之，我们的数据支持这样的假设，即树栖动物的长而可移动的尾巴在四足行走在狭窄和可移动的基质上时，具有增强稳定性的生物学作用。尾巴角动量可以用来抵消身体其他部分在稳态运动中产生的角动量，从而减少全身角动量，促进稳定性，也可以用来减轻动物遇到大的、意想不到的扰动时，关于支撑的不稳定力矩的影响。总的来说，这些研究表明，长而可移动的尾巴应该被认为是促进安全和有效的树栖运动的基本适应性之一。
Locomotion on the narrow and compliant supports of the arboreal environment is inherently precarious. Previous studies have identified a host of morphological and behavioral specializations in arboreal animals broadly thought to promote stability when on precarious substrates. Less well-studied is the role of the tail in maintaining balance. However, prior anatomical studies have found that arboreal taxa frequently have longer tails for their body size than their terrestrial counterparts, and prior laboratory studies of tail kinematics and the effects of tail reduction in focal taxa have broadly supported the hypothesis that the tail is functionally important for maintaining balance on narrow and mobile substrates. In this set of studies, we extend this work in two ways. First, we used a laboratory dataset on three-dimensional segmental kinematics and tail inertial properties in squirrel monkeys (Saimiri boliviensis) to investigate how tail angular momentum is modulated during steady-state locomotion on narrow supports. In the second study, we used a quantitative dataset on quadrupedal locomotion in wild platyrrhine monkeys to investigate how free-ranging arboreal animals adjust tail movements in response to substrate variation, focusing on kinematic measures validated in prior laboratory studies of tail mechanics (including the laboratory data presented). Our laboratory results show thatS. boliviensissignificantly increase average tail angular momentum magnitudes and amplitudes on narrow supports, and primarily regulate that momentum by adjusting the linear and angular velocity of the tail (rather than via changes in tail postureper se). We build on these findings in our second study by showing that wild platyrrhines responded to the precarity of narrow and mobile substrates by extending the tail and exaggerating tail displacements, providing ecological validity to the laboratory studies of tail mechanics presented here and elsewhere. In conclusion, our data support the hypothesis that the long and mobile tails of arboreal animals serve a biological role of enhancing stability when moving quadrupedally over narrow and mobile substrates. Tail angular momentum could be used to cancel out the angular momentum generated by other parts of the body during steady-state locomotion, thereby reducing whole-body angular momentum and promoting stability, and could also be used to mitigate the effects of destabilizing torques about the support should the animals encounter large, unexpected perturbations. Overall, these studies suggest that long and mobile tails should be considered among the fundamental suite of adaptations promoting safe and efficient arboreal locomotion.