Zaina Saab
Pronouns: she/her
Research Mentor(s): Alison Davis Rabosky
Research Mentor School/College/Department: Ecology and Evolutionary Biology / LSA
Program: UROPF
Session: Session 1 (9:00am – 9:50am)
Authors: Zaina Saab, Elaina Kern, Hayley Crowell, Natasha Stepanova, Haley Marton, Alison Davis Rabosky
Abstract
The ability to invade and occupy novel habitats requires changes to existing complex traits, such as vision, and can result in multiple morphological phenotypes. In most vertebrate eyes, light enters through a layer of tissue known as the cornea, which is then refracted through the lens. Snake eyes, however, are uniquely structured in that they do not blink, lack ciliary muscles, and focus their vision by pushing their lens forward rather than adjusting the shape of the lens like most terrestrial vertebrates. Based on previous research of snake eye morphology, it was found that variations in corneal thickness proves advantageous in different ecological habitats. What remains largely unexplored is how lens morphology differs among snake ecomorphs and if there is a correlation between the lens volume and corneal thickness. In this study, we sampled snake species using computed tomography scans (CT-scans) to segment and measure the lens morphology of each specimen. Using data from previous morphological studies on snake vision, we investigated the relationship between snake corneal thickness and lens volume and diameter to test for correlations between eye anatomical elements and snake ecomorphology. We predict that snakes residing in darker environments (such as fossorial species) depend less on eyesight as they do not have an evolutionary need for the same vision capacity as other snake ecomorphs (terrestrial, aquatic, and arboreal), therefore resulting in a loss of corneal thickness and lens volume. Comparatively, we expect arboreal snakes to have the highest visual capacities due to their need to navigate more complex environments. Differences in eye morphology between snake ecotypes could demonstrate multiple possible pathways for complex traits to evolve as a result of novel habitat invasion.
