AbstractsBiology & Animal Science

This dissertation project seeks to elucidate the biomechanics of crouched locomotion in small mammals using natural, ecologically relevant perturbations — aging and substrate. The second chapter of this dissertation examines locomotion and sarcopenia in the aging rat, arguably one of most well-studied model vertebrates. Rather than focusing on rats as human models, however, this paper addresses some of the specific challenges encountered by small, crouched animals, the importance of incorporating whole-animal performance measures, and finally how aging might be used as a model experimental technique. The third and fourth chapters of this study address four aspects of tunnel (“subterranean”) locomotion — posture, gait, COM mechanics and energetic cost of locomotion — with comparison to epigean (unconstrained, or overground) conditions. These data are then synthesized to broadly illustrate the performance consequences of tunnel locomotion in small mammals, with particular focus on how mammals may conserve metabolic energy via mechanical and anatomical adaptations. The focus of the third chapter is the locomotion of the domestic ferret( Mustela putorious furo ) moving on a force trackway. For this, gaits, posture and center-of-mass mechanics were used as metrics of performance. The fourth chapter is an investigation of the energetic cost of moving in tunnels, with reference to the data from the force trackway study. As an additional test of putative semi-fossorial adaptations, two related rodent species (the semi-fossorial degu, Octodon degus , and the generalist guinea pig, Cavia porcellus ) were also measured in both experimental conditions to assess what energetic benefits or costs might be associated with semi-fossoriality.