Sensory Structures in Sceloporus Evolve in Concert: Comparing Skull Morphology Between Blue and White-Bellied Sceloporus

Skulls house sensory systems that perceive communicative signals and may be shaped by behavior over evolutionary time. Here, I used an indicator trait (presence of a blue patch used as a sexual signal and linked to differences in sensory behavior) to test whether Sceloporus lizard species that rely more on olfactory behavior differ in skull morphology and sensory structures from those that rely more on visual behavior. We marked specific morphological points on Sceloporus skulls to compare the distances between significant sensory structures, such as eye orbit and snout length. Adjusting for body length, I found that white-bellied lizards have a wider snout tip, suggesting more evolutionary investment in chemosensory structures. White-bellied lizards also had a pattern of larger olfactory and visual skull morphology. Finally, I found a strong robust positive correlation between visual and olfactory structures. Together, our results support a hypothesis of strong integration between sensory structures, suggesting that vision and olfaction are evolving in concert rather than independently in Sceloporus lizards.