Do Adult Phenotypes Reflect Selection on Juvenile Performance? A Comparative Study on Performance and Morphology in Lizards.

When competing for food or other resources, or when confronted with predators, young animals may be at a disadvantage relative to adults because of their smaller size. Additionally, the ongoing differentiation and growth of tissues may constrain performance during early ontogenetic stages. However, juveniles must feed before they can become reproductively active adults and as such the adult phenotype may be the result of an ontogenetic filter imposing selection on juvenile phenotype and performance. Here we present ontogenetic data on head morphology and bite force for different lizard species. We test whether adults reflect selection on juveniles by comparing slopes of growth trajectories before and after sexual maturity in males and females and by examining the variance in head morphology and bite force in juveniles versus adults. Finally, we also present the first results of a selection study where animals were measured, marked and released, and recaptured the subsequent year to test whether head morphology and bite force impact survival.