Meeting Abstract

P1.117  Wednesday, Jan. 4  Evolutionary rates and patterns of sexual shape dimorphism in the shells of emydid turtles RIVERA, G*; HANSEL, MM; ADAMS, DC; Iowa State University, Ames; Iowa State University, Ames; Iowa State University, Ames grivera@iastate.edu

Sex-based differences in shell shape have been identified in many species of turtle. Despite the functional importance of shell shape in turtles, sexual shape dimorphism (SShD) has received considerably less attention than sexual size dimorphism (SSD). In addition, most studies of SShD have focused on specific species rather than evolutionary patterns. In this study we examined sexual dimorphism in carapace shape from a broad sampling of emydid turtles. Three-dimensional coordinates were collected for landmarks from the shells of museum specimens and superimposed using the generalized Procrustes method. Multivariate techniques were used to quantify the magnitude and direction of differences in shell shape between sexes. We also used the comparative phylogenetic method to map SShD and SSD magnitudes onto an existing phylogeny of emydid turtles. This approach provided insight into several evolutionary patterns related to SShD in emydid turtles, including: (1) strong phylogenetic patterns in the direction and magnitude of SShD; (2) significant correlations between the magnitudes of SShD and SSD in the Deirochelyinae, but not the Emydinae; and (3) significantly greater rates of evolution for SSD compared to SShD. Implications of findings will be discussed.