Meeting Abstract

P3.67  Saturday, Jan. 5  Developmental temperature affects larval anuran shape trajectories JORGENSEN, Michael/E.*; SHEIL, Christopher; Ohio University mj207406@ohio.edu

Few studies have quantified and described the differences in ontogenetic trajectories of developing amphibians. Here, differences in larval anuran ontogeny are examined after manipulating an abiotic developmental factor��temperature. Developmental series of American Toad (Anaxyrus americanus) larvae were collected from four temperature treatments (constant Mean, constant High, constant Low, and Fluctuating), representing Gosner Stages 27�40. Cleared and stained larval-chondrocrania were analyzed with landmark-based geometric morphometrics. A 2-factor MANCOVA was used to assess chondrocranial allometry, as well as differences in chondrocranial shape among temperature treatments and Gosner stages with effects of allometry held constant. Magnitude and direction of temperature-treatment vectors were also used in a residual randomization procedure to test differences among treatment ontogenies. Variances of temperature treatments and Gosner Stages were significant, as well as the magnitude and direction of treatment-ontogeny vectors. Shape differences among temperature treatments are visualized in 3D size/shape space with thin-plate splines. Results indicate that larvae sampled from Mean and Fluctuating temperature treatments converge at a similar shape later in development, despite shape differences observed early in development. Larvae sampled from High and Low temperature treatments are more similar in shape to Mean and Fluctuating treatment individuals earlier in ontogeny and diverge from them as ontogeny progresses. This suggests that larval Anaxyrus americanus ontogeny is dependent upon developmental temperature regime, and that larvae can arrive at similar terminal shapes in moderate and fluctuating temperature regimes.