title: The evolution of locomotor rhythmicity in tetrapods.
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.
authors.affiliation: Organismal Biology & Anatomy, University of Chicago, 1027 East 57th Street, Chicago, Illinois 60637, USA. rossc@uchicago.edu
authors.forename: Callum F
authors.initials: CF
authors.lastname: Ross
authors.forename: Richard W
authors.initials: RW
authors.lastname: Blob
authors.forename: David R
authors.initials: DR
authors.lastname: Carrier
authors.forename: Monica A
authors.initials: MA
authors.lastname: Daley
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Deban
authors.forename: Brigitte
authors.initials: B
authors.lastname: Demes
authors.forename: Janaya L
authors.initials: JL
authors.lastname: Gripper
authors.forename: Jose
authors.initials: J
authors.lastname: Iriarte-Diaz
authors.forename: Brandon M
authors.initials: BM
authors.lastname: Kilbourne
authors.forename: Tobias
authors.initials: T
authors.lastname: Landberg
authors.forename: John D
authors.initials: JD
authors.lastname: Polk
authors.forename: Nadja
authors.initials: N
authors.lastname: Schilling
authors.forename: Bieke
authors.initials: B
authors.lastname: Vanhooydonck
mesh_terms: D000818:Animals; D001717:Birds / Q000235:genetics*; D019143:Evolution, Molecular; D005684:Gait; D008124:Locomotion / Q000235:genetics* / Q000502:physiology; D008322:Mammals / Q000235:genetics*; D010507:Periodicity; D010802:Phylogeny; D012104:Reptiles / Q000235:genetics*