Linking morphology and performance: skeletal growth and sex-specific form–function relationships in an agamid lizard

Abstract

Linking morphology to performance is essential for understanding how skeletal growth shapes functional capabilities. In sexually dimorphic species, males and females often experience distinct selection pressures, leading to differences in growth rate, allometric patterns and adult performance. Using longitudinal X-ray imaging, we quantified skeletal growth in the agamid lizard, Psammophilus dorsalis, from juvenile to adult stages, to examine sex differences in growth trajectories, allometric patterns, whole-body performance and morphology–performance relationships. We found that body length increased non-linearly in both sexes and growth trajectories were parallel. Key morphological traits scaled isometrically relative to body length. As adults, sexes did not differ in absolute sprint speed, but males had higher absolute bite force. Hindlimb length and body shape poorly predicted sprint speed, but head length predicted bite force in females. Overall, our results suggest broadly similar growth patterns and performance outcomes in both sexes, indicating possible constraints on morphology and performance.