Wunderlich R E, Tongen A, Gardiner J, Miller C E, Schmitt D
*Department of Biology, James Madison University, Harrisonburg, VA 22807, USA; Department of Mathematics, James Madison University, Harrisonburg, VA 22807, USA; Division of Biology, University of South Wales, Cardiff, UK; Department of Evolutionary Anthropology, Duke University, Durham, NC 27710, USA
*Department of Biology, James Madison University, Harrisonburg, VA 22807, USA; Department of Mathematics, James Madison University, Harrisonburg, VA 22807, USA; Division of Biology, University of South Wales, Cardiff, UK; Department of Evolutionary Anthropology, Duke University, Durham, NC 27710, USA.
Integr Comp Biol. 2014 Dec;54(6):1148-58. doi: 10.1093/icb/icu110. Epub 2014 Sep 17.
Most primates are able to move with equal facility on the ground and in trees, but most use the same quadrupedal gaits in both environments. A few specialized primates, however, use a suspensory or leaping mode of locomotion when in the trees but a bipedal gait while on the ground. This is a rare behavioral pattern among mammals, and the extent to which the bipedal gaits of these primates converge and are constrained by the anatomical and neurological adaptations associated with arboreal locomotion is poorly understood. Sifakas (Propithecus), primates living only in Madagascar, are highly committed vertical clingers and leapers that also spend a substantial amount of time on the ground. When moving terrestrially sifakas use a unique bipedal galloping gait seen in no other mammals. Little research has examined the mechanics of these gaits, and most of that research has been restricted to controlled captive conditions. The energetic costs associated with leaping and bipedal galloping are unknown. This study begins to fill that gap using triaxial accelerometry to characterize and compare the dynamics of sifakas' leaping and bipedal galloping behavior. As this is a relatively novel approach, the first goal of this article is to explore the feasibility of collecting such data on free-roaming animals and attempt to automate the identification of leaping and bipedal behavior within the output. The second goal is to compare the overall accelerations of the body and to use that as an approximation of aspects of energetic costs during leaping and bipedalism. To achieve this, a lightweight accelerometer was mounted on freely moving sifakas. The resulting acceleration profiles were processed, and sequences of leaps (bouts) were automatically extracted from the waveforms with 85% accuracy. Both vector dynamic body acceleration and overall dynamic body acceleration (ODBA) were used to characterize locomotor patterns and energy expenditure during leaping and bipedalism. The unique kinematics of the gait of sifakas, and the mechanics of bouts involving a string of successive leaps or gallops, appear to minimize redirections of the center of mass as well as the number of acceleration peaks and ODBAs. These results suggest that bipedal galloping is not only a reflection of the unique anatomical configuration of a leaping primate, but it may also provide a musculoskeletal and an energetic advantage to sifakas. In that sense, bipedal galloping represents an advantageous way for sifakas to move when transitioning from arboreal leaping to terrestrial locomotion.
大多数灵长类动物在地面和树上都能同样自如地移动，但在这两种环境中大多使用相同的四足步态。然而，一些特化的灵长类动物在树上时采用悬荡或跳跃的运动方式，而在地面上则采用双足步态。这在哺乳动物中是一种罕见的行为模式，而且对于这些灵长类动物的双足步态在多大程度上趋同以及受到与树栖运动相关的解剖学和神经学适应的限制，人们了解甚少。冕狐猴（鼬狐猴属）是仅生活在马达加斯加的灵长类动物，它们是高度专注的垂直攀缘和跳跃者，也会在地面上花费大量时间。当在陆地上移动时，冕狐猴会使用一种其他哺乳动物都没有的独特双足疾驰步态。很少有研究考察这些步态的力学原理，而且其中大部分研究都局限于受控的圈养条件。与跳跃和双足疾驰相关的能量消耗尚不清楚。本研究开始利用三轴加速度测量法来填补这一空白，以表征和比较冕狐猴跳跃和双足疾驰行为的动力学。由于这是一种相对新颖的方法，本文的首要目标是探索在自由活动的动物身上收集此类数据的可行性，并尝试在输出结果中自动识别跳跃和双足行为。第二个目标是比较身体的整体加速度，并将其用作跳跃和双足行走过程中能量消耗方面的近似值。为实现这一目标，在自由活动的冕狐猴身上安装了一个轻便的加速度计。对得到的加速度曲线进行了处理，并以85%的准确率从波形中自动提取出跳跃序列（回合）。矢量动态身体加速度和整体动态身体加速度（ODBA）都被用来表征跳跃和双足行走过程中的运动模式和能量消耗。冕狐猴步态独特的运动学特征，以及涉及一连串连续跳跃或疾驰的回合的力学原理，似乎能将质心的重新定向以及加速度峰值和ODBA的数量降至最低。这些结果表明，双足疾驰不仅反映了一种跳跃灵长类动物独特的解剖结构，而且可能还为冕狐猴提供了肌肉骨骼和能量方面的优势。从这个意义上说，双足疾驰是冕狐猴从树栖跳跃过渡到陆地运动时一种有利的移动方式。
