THE EVOLUTION OF BIPEDAL RUNNING IN LIZARDS SUGGESTS A CONSEQUENTIAL ORIGIN MAY BE EXPLOITED IN LATER LINEAGES
Version of Record online: 3 JUN 2014
© 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.
Volume 68, Issue 8, pages 2171–2183, August 2014
How to Cite
Clemente, C. J. (2014), THE EVOLUTION OF BIPEDAL RUNNING IN LIZARDS SUGGESTS A CONSEQUENTIAL ORIGIN MAY BE EXPLOITED IN LATER LINEAGES. Evolution, 68: 2171–2183. doi: 10.1111/evo.12447
- Issue online: 1 AUG 2014
- Version of Record online: 3 JUN 2014
- Accepted manuscript online: 12 MAY 2014 03:39PM EST
- Manuscript Accepted: 11 APR 2014
- Manuscript Received: 14 OCT 2013
- Adaptive radiations;
- co-opted traits;
- morphological evolution;
- rates of evolution
The origin of bipedal locomotion in lizards is unclear. Modeling studies have suggested that bipedalism may be an exaptation, a byproduct of features originally designed to increase maneuverability, which were only later exploited. Measurement of the body center of mass (BCOM) in 124 species of lizards confirms a significant rearward shift among bipedal lineages. Further racetrack trials showed a significant acceleration threshold between bipedal and quadrupedal runs. These suggest good general support for a passive bipedal model, in which the combination of these features lead to passive lifting of the front of the body. However, variation in morphology could only account for 56% of the variation in acceleration thresholds, suggesting that dynamics have a significant influence on bipedalism. Deviation from the passive bipedal model was compared with node age, supporting an increase in the influence of dynamics over time. Together, these results show that bipedalism may have first arisen as a consequence of acceleration and a rearward shift in the BCOM, but subsequent linages have exploited this consequence to become bipedal more often, suggesting that bipedalism in lizards may convey some advantage. Exploitation of bipedalism was also associated with increased rates of phenotypic diversity, suggesting exploiting bipedalism may promote adaptive radiation.