Meeting Abstract

13.1  Wednesday, Jan. 4  A comparative assessment of musculoskeletal development in basal actinopterygians DAVIS, Marcus C. ; Kennesaw State University

The pattern of musculoskeletal development has been extensively studied in tetrapods and in the derived actinopterygians (teleosts). What is lacking are adequate descriptions of muscle and skeletal growth in more basal osteichthyan taxa, such as the non-teleost actinopterygians. Here we assess the patterns of associated muscle and skeletal element formation during embryonic and larval development in the basal actinopterygians Polyodon spathula, Lepisosteus osseus, and Amia calva using immunostained whole-mount and sectioned material. When placed in the phylogenetic context of more derived taxa, these data provide insights into the conserved musculoskeletal developmental pattern considered primitive for Osteichthyes. As such, these results will also provide crucial tests of previous hypotheses of muscle homology and evolution in teleosts and tetrapods. A similar pattern of early recruitment of muscle groups necessary for ventilation, feeding, and vision is observed in all three taxa. This observation supports the notion that common environmental and physiological constraints also play a role in determining the order (and timing) of appearance of certain functional musculoskeletal systems. Despite such conservation and constraint, the distinct morphologies that characterize each taxon (i.e. musculoskeletal proportions and the specific connections between elements) emerge early in the developmental program.