Evaluating head shape morphology and somatic growth rate variation in Komodo dragons over ontogeny

By identifying selective factors that induce evolutionary changes in the vertebrate heads can detail how complex evolutionary responses maintain species persistence. For example, differences in head shape morphology can result from specialisations in feeding biology and reproduction. Thus, explaining differences in skull morphologies may mean identifying evidence of selection pressures and trade-offs. The architecture of the Komodo dragon (Varanus komodoensis) is a consequence of evolutionary changes responding to sources of selection. This study seeks evidence of forces, including natural, sexual and fecundity selection acting on the Komodo dragon head shape and the underlying somatic growth rates observed across ontogeny. I predicted a departure from isometry in head shape morphology and head growth rates. To assess head shape changes over ontogeny, a Procrustes PCA paired with PerMANOVAS to statistically and visually represent variations in head shapes in 5 age classes. To evaluate changes in growth dynamics: GAMMs, GLMMs, and a coefficient plot would show variations of head and cervical-sacral length growth patterns between. This study found evidence of allometric growth in male head shapes. There was also strong evidence of sexual and fecundity selection on head shape morphology. This was supported by differences in growth trajectories between the sexes, with males’ experiencing strong non-monotonic growth compared to negative linear growth in females.