Meeting Abstract

43.5  Tuesday, Jan. 5  Patterns of axial and pelvic muscle architecture and fiber composition in frogs with different locomotor modes JORGENSEN, M.E.; Ohio University mj207406@ohio.edu

The composition of fiber types in a muscle, along with its gross architecture corresponds to muscle function. In frog limbs, jumping involves muscles comprised mainly of high force-producing glycolytic muscle fibers that contract rapidly during an escape. On the other hand, muscles comprised mainly of slow oxidative fibers maintain a high endurance capacity and are used for posture and slow repetitive behaviors such as walking, burrowing, or hopping. Axial and pelvic muscles in frogs are poorly understood even though they control vertebral column rigidity, direct sagittal and lateral bending of the vertebral column and pelvis, and function as takeoff-angle regulators to align the anterior half of the frog with the legs and pelvis before and during jump take-off. The goal of this study is to examine variation in vertebral musculoskeletal architecture and muscle fiber-type composition in axial and pelvic muscles of frogs with different locomotor behaviors. I quantified vertebral morphology, muscle architecture (anatomical cross-sectional area, muscle length, tendon length) and fiber-type composition of axial and pelvic muscles in a sample of species and locomotor modes used in frogs (Ascaphus, Xenopus, Bombina, Anaxyrus, Lithobates). Patterns of variation in muscle architecture and fiber-type composition are presented and discussed in light of different locomotor behaviors and current hypotheses of the evolution of locomotion in frogs.