Meeting Abstract

P2.103  Monday, Jan. 5  Intraspecific variation in chondrocranial morphology of wood frog tadpoles (Rana sylvatica) LARSON, PM*; RAABIS, S; BRICK, A; CORRIVEAU, J; HALL, H; LENIHAN, P; MAY, S; St. Anselm College; St. Anselm College; St. Anselm College; St. Anselm College; St. Anselm College; St. Anselm College; St. Anselm College plarson@anselm.edu

This study investigates intraspecific variation in chondrocranial morphology among tadpoles derived from three wood frog (Rana sylvatica) egg masses collected from a single vernal pool. Results indicate that chondrocranial shape differs significantly among samples of tadpoles derived from the three egg masses, even when reared under identical laboratory conditions and matched for size and developmental stage. Thus, these results suggest that the variation observed is genetic in origin, and not simply due to environmental influences on the development of the tadpole chondrocranium. Primary areas of variation include the width of the muscular process of the palatoquadrate, the size of the palatoquadrate articular process, the distance between the upper jaw articulation sites (= gape width), and the anatomy of the posterior portion of the palatoquadrate. Given the close association of these structures with anatomical elements critical to feeding and respiration (e.g., mandibular and hyoid arch muscles, jaw cartilages), all of these areas represent functionally important regions of the chondrocranium. Although little is known about the potential selective advantages (if any) of any of these anatomical variations, or their heritabilities, the existence of discrete, presumably genetically based intraspecific variation at this small scale satisfies one of the major requirements necessary for natural selection to act as an agent driving interspecific changes in tadpole morphology.