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The Functional Morphology of Lizard Locomotion: Integrating Biomechanics,Kinematics, Morphology, and Behavior

McElroy, Eric J.

Abstract Details

2008, Doctor of Philosophy (PhD), Ohio University, Biological Sciences (Arts and Sciences).

Lizards have long served as a model system for understanding how locomotor functional morphology meets ecological demands. However, far less is known about how behavior modulates this relationship. Likewise, there is still a need for a comprehensive understanding of lizard locomotor functional morphology. This dissertation presents four studies that focus on how behavior molds locomotion and advances our understanding of lizard locomotor functional morphology.

Chapter one examines variation in locomotor performance, whole-body mechanics and gaits in a phylogenetic array of lizards that use differing foraging modes. Multivariate and phylogenetic comparative analyses show that foraging mode drives the evolution of biomechanics and gaits in lizards. Sit-and-wait species used only fast speeds, trotting gaits, and running mechanics, whereas wide foraging species independently evolved slower locomotion, different walking gaits, and walking mechanics.

Chapter two examines patterns of variation in the hierarchical relationship among morphology, kinematics and force during fast running in seven species of lizards. Multivariate analyses test for correlations among levels to reveal the morphological basis for kinematics and locomotor forces. The results show that limb length, support duration and float distance directly influence the nature of forces applied to the ground during the support phase of steady state locomotion and suggest that this relationship may affect locomotor energetics and endurance.

Chapter three examines the effects of habitat, behavior, and their interaction on undisturbed locomotor speeds in Urosaurus ornatus. Detailed video analysis of undisturbed behavior reveals that locomotor speed decreases with increasing perch height, when animals move on woody substrates, and while displaying and capturing prey. No relationship is found between speed and perch diameter or substrate incline. Finally, the interaction between perch diameter and feeding behavior results in a negative relationship between speed and perch diameter during feeding but not during other behaviors. I suggest that the relationship between habitat, behavior, and speed is affected by the level of locomotor performance (maximal vs. sub maximal) that animals routinely use during undisturbed activity.

Finally, chapter four presents a detailed analysis of foraging behavior and field locomotor performance in a sit-and-wait (Sceloporus undulatus) and wide foraging (Aspidoscelis flagellicaudus) species. Both sit-and-wait and wide foraging species clump relatively slow locomotor behaviors just before prey attacks, a finding at odds with hypotheses from the literature. This result, along with previous studies, suggests that selection on maximum speed and endurance is not acting through the filter of foraging behavior. I suggest that foraging mode should be examined in light of an existing model of animal foraging (the Webb model) to direct future studies of the ecology and evolution of animal performance in relation to foraging behavior.

Stephen M. Reilly, Ph.D (Advisor)
182 p.

Recommended Citations

Citations

  • McElroy, E. J. (2008). The Functional Morphology of Lizard Locomotion: Integrating Biomechanics,Kinematics, Morphology, and Behavior [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1213879506

    APA Style (7th edition)

  • McElroy, Eric. The Functional Morphology of Lizard Locomotion: Integrating Biomechanics,Kinematics, Morphology, and Behavior. 2008. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1213879506.

    MLA Style (8th edition)

  • McElroy, Eric. "The Functional Morphology of Lizard Locomotion: Integrating Biomechanics,Kinematics, Morphology, and Behavior." Doctoral dissertation, Ohio University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1213879506

    Chicago Manual of Style (17th edition)