Meeting Abstract
Most amphibians have two distinct periods of development; embryogenesis which results in the formation of the larval stage, and metamorphosis which transforms the larva into an adult. The most dramatic metamorphic transformations occur in frogs where virtually every tissue is remodeled. The current work uses myosin antibodies and whole-mount immunohistochemistry to describe jaw and buccal pump muscle development and metamorphosis in tadpoles of Eastern Narrowmouth Toads (Gastrophryne carolinensis), American Toads (Anaxyrus americanus), and Gray Treefrogs (Hyla versicolor/chrysoscelis). Narrowmouth Toads differ from the other species in having a more anterior origin of the levator mandibulae muscles from the palatoquadrate, reduced size and dorsal-most margin of the orbitohyoideus, and increased size and more oblique fiber orientation of the interhyoideus. Similar differences have been reported in previous work comparing microhylid tadpoles with members of other frog families. Architectural changes in the orbitohyoideus and interhyoideus in Narrowmouth toads are associated with filter feeding of small-suspended particles as opposed to an ancestral generalized feeding strategy based on scraping food from the substrate using keratinized mouthparts. Ontogenetic changes in muscle fiber angles between the orbitohyoideus and the levator mandibulae, and the ratio between the interhyoideus and orbitohyoideus also differ among feeding strategies. Our descriptions of jaw muscle development in G. carolinensis are consistent with decreased developmental rate and early offset of jaw development as has been hypothesized for closely related frogs with similar feeding strategies.
