title: Speed-dependent modulation of wing muscle recruitment intensity and kinematics in two bat species.
abstract: 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 insectivoreEptesicus fuscus, and the primarily fruit-eatingCarollia perspicillataThese 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 inE. fuscusand modulated in a U-shaped or linearly increasing relationship with speed inC. perspicillataThis 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. fuscusmodulates wing flexion during upstroke significantly more thanC. perspicillataOverall, we observed two different strategies to increase flight speed:C. perspicillatatends to modulate aEMG, andE. fuscustends 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.
authors.affiliation: Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA Nicolai_konow@uml.edu.
authors.forename: Nicolai
authors.identifier: 0000-0003-3310-9080
authors.initials: N
authors.lastname: Konow
authors.affiliation: Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.
authors.forename: Jorn A
authors.initials: JA
authors.lastname: Cheney
authors.affiliation: Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Roberts
authors.affiliation: Department of Oral Biology, University of Illinois at Chicago, Chicago, IL 60612, USA.
authors.forename: Jose
authors.initials: J
authors.lastname: Iriarte-Díaz
authors.affiliation: Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.|School of Engineering, Brown University, Providence, RI 02912, USA.
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Breuer
authors.affiliation: Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.|Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA.
authors.forename: J Rhea S
authors.initials: JRS
authors.lastname: Waldman
authors.affiliation: Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.|School of Engineering, Brown University, Providence, RI 02912, USA.
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Swartz
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002685:Chiroptera / Q000502:physiology*; D004576:Electromyography; D005260:Female; D005426:Flight, Animal / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D014921:Wings, Animal
keywords: Lifting surface; Locomotor performance; Movement economy; Muscle activity; Wing morphing; Wings