Tail function during arboreal quadrupedalism in squirrel monkeys (Saimiri boliviensis) and tamarins (Saguinus oedipus).
Tail function during arboreal quadrupedalism in squirrel monkeys (Saimiri boliviensis) and tamarins (Saguinus oedipus).
复制标题
DOI：
10.1002/jez.1948
复制
发表时间：
2015-10
期刊：
影响因子：
--
通讯作者：
J. Young;G. Russo;C. Fellmann;Meena Thatikunta;Brad A. Chadwell
中科院分区：
文献类型：
--
作者：
J. Young;G. Russo;C. Fellmann;Meena Thatikunta;Brad A. Chadwell
在狭窄的树枝上保持稳定的需要通常被认为是塑造灵长类动物形态的主要选择力，适应性以促进抓握受到特别关注。长而移动的尾巴对于维持树体稳定性的功能重要性，相对而言研究得还不够充分。尾巴可以通过充当静态平衡物或动态惯性附件来调节全身角动量，从而促进树木平衡。我们调查尾巴的使用和推断的把握能力之间的关联，在两个密切相关的cebid platyramines棉顶绢毛猴（Saguinus俄狄浦斯）和黑帽松鼠猴（Saimiri boliviensis）。使用高速摄像的圈养猴子在3.2厘米直径的杆上移动，我们专门测试的假设，松鼠猴（其特点是抓住四肢长的手指）将不太依赖于尾巴的平衡比绢毛猴（其特点是爪状指甲，短的手指，和减少拇趾）。绢毛猴的尾巴比松鼠猴长，它们的尾巴以更大的角振幅、更高的角速度和更大的角加速度移动，这表明它们动态地使用尾巴来调节全身的角动量。相比之下，松鼠猴通常以相对静止的姿势和更低的角度保持尾巴，这表明了静态平衡机制。这项研究，第一次经验性测试的功能之间的权衡把握能力和尾巴使用的树栖灵长类动物，表明在树栖四足动物的尾巴在维持稳定的关键作用。我们的研究结果有可能为我们对灵长类进化过程中尾巴丢失的功能理解提供信息。
The need to maintain stability on narrow branches is often presented as a major selective force shaping primate morphology, with adaptations to facilitate grasping receiving particular attention. The functional importance of a long and mobile tail for maintaining arboreal stability has been comparatively understudied. Tails can facilitate arboreal balance by acting as either static counterbalances or dynamic inertial appendages able to modulate whole-body angular momentum. We investigate associations between tail use and inferred grasping ability in two closely related cebid platyrrhines-cotton-top tamarins (Saguinus oedipus) and black-capped squirrel monkeys (Saimiri boliviensis). Using high-speed videography of captive monkeys moving on 3.2 cm diameter poles, we specifically test the hypothesis that squirrel monkeys (characterized by grasping extremities with long digits) will be less dependent on the tail for balance than tamarins (characterized by claw-like nails, short digits, and a reduced hallux). Tamarins have relatively longer tails than squirrel monkeys, move their tails through greater angular amplitudes, at higher angular velocities, and with greater angular accelerations, suggesting dynamic use of tail to regulate whole-body angular momentum. By contrast, squirrel monkeys generally hold their tails in a comparatively stationary posture and at more depressed angles, suggesting a static counterbalancing mechanism. This study, the first empirical test of functional tradeoffs between grasping ability and tail use in arboreal primates, suggests a critical role for the tail in maintaining stability during arboreal quadrupedalism. Our findings have the potential to inform our functional understanding of tail loss during primate evolution.