Meeting Abstract
Accounts of sexual dimorphism in skates are often limited to tooth morphology, alar and malar thorns, and linear dimensions of the body. However, the extent of dimorphism between male and female skates can be quite substantial, involving several morphological features that are vital to the lifestyle of the organism. For this research, we assess the development and divergence of pectoral fin morphologies, review the extent of dimorphism within the endoskeletal system, and discuss the prevalence of dimorphism across skate diversity. Geometric morphometrics of pectoral fin outlines and endoskeletons of two Leucoraja species revealed different morphological trajectories for males and females. A rapid change in shape at maturation was identified for males and coincided with skeletal elongation of external reproductive organs, the claspers. Interspecific differences in the magnitude of the morphological transformation appeared to be related to life history variation, namely the relative rates of maturation. Additionally, MicroCT scans of Fenestraja plutonia allowed us to identify dimorphism in the pelvic girdle, pectoral girdle, jaws, and neurocranium. Finally, we found evidence of dimorphism in a majority of skate genera, spanning all major subclades. Our understanding of sexual dimorphism in skates remains limited, but this research suggests that divergent morphologies may be intimately linked to the evolution of life histories and reproductive strategies of these fishes.
