Speed-dependent modulation of wing muscle recruitment intensity and kinematics in two bat species
Speed-dependent modulation of wing muscle recruitment intensity and kinematics in two bat species
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DOI：
10.1242/jeb.144550
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发表时间：
2017-05-01
影响因子：
2.8
通讯作者：
Swartz, Sharon M.
中科院分区：
文献类型：
--
作者：
Konow, Nicolai;Cheney, Jorn A.;Swartz, Sharon M.
动物通过调节推进肌肉组织的募集强度来响应运动过程中功率需求的变化，但关于肌肉募集如何随运动模式的速度而变化的许多问题仍然没有答案。我们测量了归一化平均爆发肌电图（aEMG）的胸大肌和肱二头肌在不同的飞行速度在两个相对较远的蝙蝠物种：空中食虫动物Eptesicus fuscus，和主要吃水果的Ephallia perspicillata。这些生态上不同的物种采用不同的飞行行为，但具有相似的翼展弦比，翼载荷和身体质量。由于推进需求通常与身体大小相关，并且aEMG可能反映力量，因此我们假设这些物种会部署类似的速度依赖性aEMG调制。相反，我们发现aEMG在E.在C.多刺的这种种间差异可能与肌纤维类型组成和/或参与致动高度铰接的蝙蝠翅膀的大型肌肉集合的整体招募模式的差异有关。我们还发现了种间差异的速度依赖的三维翅膀运动学：E。fuscus在上击过程中调节翅屈曲的作用显著大于C.多刺的总的来说，我们观察到两种不同的策略来增加飞行速度：C。perspicillata倾向于调节aEMG，E. fuscus倾向于调节翅膀的运动学。这些策略可能分别反映了在慢速和快速飞行中避免负升力和克服阻力的不同要求，我们建议进一步研究这一主题。
Animals respond to changes in power requirements during locomotion by modulating the intensity of recruitment of their propulsive musculature, but many questions concerning how muscle recruitment varies with speed across modes of locomotion remain unanswered. We measured normalized average burst EMG (aEMG) for pectoralis major and biceps brachii at different flight speeds in two relatively distantly related bat species: the aerial insectivore Eptesicus fuscus, and the primarily fruit-eating Carollia perspicillata. These ecologically distinct species employ different flight behaviors but possess similar wing aspect ratio, wing loading and body mass. Because propulsive requirements usually correlate with body size, and aEMG likely reflects force, we hypothesized that these species would deploy similar speed-dependent aEMG modulation. Instead, we found that aEMG was speed independent in E. fuscus and modulated in a U-shaped or linearly increasing relationship with speed in C. perspicillata. This interspecific difference may be related to differences in muscle fiber type composition and/or overall patterns of recruitment of the large ensemble of muscles that participate in actuating the highly articulated bat wing. We also found interspecific differences in the speed dependence of 3D wing kinematics: E. fuscus modulates wing flexion during upstroke significantly more than C. perspicillata. Overall, we observed two different strategies to increase flight speed: C. perspicillata tends to modulate aEMG, and E. fuscus tends to modulate wing kinematics. These strategies may reflect different requirements for avoiding negative lift and overcoming drag during slow and fast flight, respectively, a subject we suggest merits further study.