THE EVOLUTION OF LOCOMOTOR RHYTHMICITY IN TETRAPODS |
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| Authors: | Callum F Ross Richard W Blob David R Carrier Monica A Daley Stephen M Deban Brigitte Demes Janaya L Gripper Jose Iriarte‐Diaz Brandon M Kilbourne Tobias Landberg John D Polk Nadja Schilling Bieke Vanhooydonck |
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| Institution: | 1. Organismal Biology & Anatomy, University of Chicago, 1027 East 57th Street, Chicago, Illinois 60637;2. E‐mail: rossc@uchicago.edu;3. Biological Sciences, 342 Long Hall, Clemson University, Clemson, South Carolina 29634;4. Department of Biology, 201 South Biology Building, University of Utah, Salt Lake City, Utah 84112;5. Structure and Motion Laboratory, The Royal Veterinary College, University of London, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, United Kingdom;6. Department of Integrative Biology, University of South Florida, 4202 East Fowler Avenue SCA 110, Tampa, Florida 33620;7. Anatomical Sciences, Stony Brook University, Stony Brook, New York 11794‐8081;8. The College, University of Chicago, Chicago, Illinois 60637;9. Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich‐Schiller‐Universit?t Jena, Erbertstr., 07743, Jena, Germany;10. Biology Department, Boston University, Boston, Massachusetts 02215;11. Department of Anthropology, University of Illinois at Urbana‐Champaign, 607 S Mathews Avenue, M/C 148, Urbana, Illinois 61801;12. Institute of Systematic Zoology and Evolutionary Biology, Friedrich‐Schiller‐Universit, Jena, Germany;13. Department of Biology, University of Antwerp, Universiteitsplein 1, B‐2610 Wilrijk, Belgium |
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| Abstract: | Differences in rhythmicity (relative variance in cycle period) among mammal, fish, and lizard feeding systems have been hypothesized to be associated with differences in their sensorimotor control systems. We tested this hypothesis by examining whether the locomotion of tachymetabolic tetrapods (birds and mammals) is more rhythmic than that of bradymetabolic tetrapods (lizards, alligators, turtles, salamanders). Species averages of intraindividual coefficients of variation in cycle period were compared while controlling for gait and substrate. Variance in locomotor cycle periods is significantly lower in tachymetabolic than in bradymetabolic animals for datasets that include treadmill locomotion, non‐treadmill locomotion, or both. When phylogenetic relationships are taken into account the pooled analyses remain significant, whereas the non‐treadmill and the treadmill analyses become nonsignificant. The co‐occurrence of relatively high rhythmicity in both feeding and locomotor systems of tachymetabolic tetrapods suggests that the anatomical substrate of rhythmicity is in the motor control system, not in the musculoskeletal components. |
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| Keywords: | Coordination dynamics locomotion motor control |
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