Scanning Electron Microscopy and Podarcis muralis

Caitlyn Colwell ’21

Students: Caitlyn Colwell ’21
Research Mentors: Eric Gangloff and Laura Tuhela-Reuning (OWU Department of Biological Sciences)

Have you ever used a microscope to look at slides up close? While many labs use a light microscope, about the size of a blender, Ohio Wesleyan University is fortunate to have the powerful Scanning Electron Microscope (SEM), which is about the size of a barstool. This summer, I took pictures of lizard claws under the SEM to see which characteristics benefit the lizards. What is allowing them to thrive as an invasive species in urban Cincinnati?

Urbanization, which often reduces natural resources and displaces wildlife, provides an excellent habitat for the common wall lizard (Podarcis muralis) to live and thrive. This species’ resilience may be accredited to their durable claws, which allow them to scale stone walls and other anthropogenic surfaces in Cincinnati Ohio, where they are invasive. P. muralis claws were collected from field-caught and preserved museum specimens from the 1980s. The most distal phalanx of the longest digit was collected from the right rear foot of each specimen. Samples were prepared for scanning electron microscopy through ethanol dilution, critical point drying, and gold sputter coating to ensure image quality. All samples were imaged using a ZEISS EVO LS10 Scanning Electron Microscope. Images were obtained with focus on claw shape and roughness. The claws were strikingly unique, each exhibiting distinguishable features and wear. This may be due to differences in specimen age, behavior, size, or genetics. Using geometric morphometrics, we plan to extract shape, size, and curvature data from each image and compare it with performance data to test whether these variations hold functional significance for the species.