Morphology, locomotor performance and habitat use in southern African agamids

Abstract

Understanding the relationships between form and function can help us to understand the evolution of phenotypic diversity in different ecological contexts. Locomotor traits are ecologically relevant as they reflect the ability of an organism to escape from predators, to catch prey or to defend territories. As such, locomotion provides a good model to investigate how environmental constraints may influence an organism's performance. Here, we investigate the ecomorphological relationships between limb morphology, locomotor performance (sprint speed and endurance) and habitat use in six southern African agamid species. The investigated agamid species showed differences in hind limb and toe lengths. Both of these traits were further correlated with endurance capacity. This association was supported by stepwise multiple regression analyses. However, we demonstrate trade-offs in locomotor performance traits, suggesting that specialization towards speed comes at the detriment of endurance capacity. Overall, the single arboreal species studied had longer hind limbs, a higher exertion capacity and a higher mean speed. However, for a given hind limb length, the arboreal species was slower than the other habitat specialists. This study provides insights into the evolutionary mechanisms that have driven the morphological and functional evolution in southern African agamid lizards.