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Evolution of Anuran Axial and Pelvic Musculoskeletal Traits Associated with Locomotor Modes

Jorgensen, Michael E.
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1385376238

Abstract Details

2013, Doctor of Philosophy (PhD), Ohio University, Biological Sciences (Arts and Sciences).
Frogs show a variety of locomotor behaviors (swimming; walking; burrowing; hopping; climbing; jumping; gliding) that have allowed them to radiate globally to fill a diverse array of ecological niches. Studies of frog locomotion have previously focused on the role of the hindlimbs during jumping. There remains a paucity of information regarding the functional morphology of the frog trunk and pelvis and their relation to locomotor modes. Additionally, the evolution of these locomotor traits has not been studied in a phylogenetic context. This dissertation research elucidates the relationship of the frog axial and pelvic musculoskeletal system with different frog locomotor modes to assess evolutionary patterns in locomotor morphology. In the second chapter I re-examine adult axial and pelvic bony characters with respect to pelvis type and hypothesis of primary mode of locomotion in a large taxonomic sample of exant and fossil frogs to assess the anuran basal pelvic-state and locomotor condition. Results from this research are that the lateral-bender pelvis (little to no ilial/urostyle ridges), walker/hopper condition is both basal and conserved across the Anura, the sagittal-hinge pelvis (with ilial/urostyle ridges) is correlated with long-jumping and does not appear in the phylogeny until well within the Neobatrachia, and burrowing behaviors appear to have had a canalizing effect on axial/caudal rigidity, either with bicondyly or fusion of the sacrourostylic joint. The third chapter describes covariation of whole-body skeletal morphometrics in relation to four locomotor modes and two pelvic types from 188 frog genera to establish the most reliable bony character(s) for estimating primary locomotor mode. Estimates are free from the confounding effects of phylogeny with use of newly derived comparative methods. I found the shape of the sacrum to provide the most insight into differences among locomotor modes (rather than hindlimb length as previously described), such that narrowly expanded sacral diapophyses of terrestrial jumpers are significantly smaller than those found in arboreal jumpers, walker/hoppers, and burrowers. Moreover, there appears to be strong selection for sagittal-hinge traits in frogs that evolve into terrestrial jumpers because they appear in concert regardless of phylogenetic origin. The fourth chapter is a description of the muscle fiber-type composition and anatomical cross-sectional area of muscles that move/stabilize the frog pelvis, and their relation to differences in sacral and pelvic morphology across frog locomotor modes. Fiber distribution of frog axial and pelvic muscles is similar to derived patterns of lizards and mammals, but different from that of salamanders who show the pleisiomorphic condition. While no significant differences in fiber type distribution were observed among taxa, there are substantial shape differences in muscles posited to dorsiflex the back and extend/stabilize the trunk over the pelvis. Finally, I synthesize the dissertation findings in the fifth chapter and list some suggestions for future work on locomotor function in frogs.
Stephen Reilly (Advisor)
195 p.
Morphology
Frog locomotion; evolutionary morphology; anuran

Recommended Citations

Citations

  • Jorgensen, M. E. (2013). Evolution of Anuran Axial and Pelvic Musculoskeletal Traits Associated with Locomotor Modes [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1385376238

    APA Style (7th edition)

  • Jorgensen, Michael. Evolution of Anuran Axial and Pelvic Musculoskeletal Traits Associated with Locomotor Modes. 2013. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1385376238.

    MLA Style (8th edition)

  • Jorgensen, Michael. "Evolution of Anuran Axial and Pelvic Musculoskeletal Traits Associated with Locomotor Modes." Doctoral dissertation, Ohio University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1385376238

    Chicago Manual of Style (17th edition)

ohiou1385376238
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© 2013, all rights reserved.
This open access ETD is published by Ohio University and OhioLINK.