Lizard Performance in Various Environments Demonstrates Morphology-Performance Trade-Offs

Princeton Vaughn ’22

Student: Princeton Vaughn ’22
Research Mentor: Eric Gangloff (OWU Department of Biological Sciences)

A fundamental idea in biology is that morphology (how an organism's body is shaped) affects performance (how effectively it carries out tasks like sprinting and climbing). This relationship changes in different environments. For example, if a polar bear was suddenly moved to a desert, it wouldn’t have the adaptations necessary to survive. Our study examines this relationship in the common wall lizard, a small lizard species that has become established in urban Cincinnati in the early 1950s. This experiment examines how climbing speed and gripping strength change due to differences in body structure and how this relationship changes on different surfaces. This research allows us to investigate how these lizards can respond to new kinds of habitats, provides insight into how invasive species survive in new environments, and explores how species respond to urbanization.

An organism’s morphology affects its performance, but this relationship changes in different environments and contexts. As urban environments expand, more natural substrates (the material on which an organism lives and moves) are being replaced by anthropogenic materials. As a result, many species are being negatively affected. This change in substrate impacts how animals perform important tasks like running, climbing, digging, etc. Investigating this morphology-performance relationship is necessary to understand how urbanization impacts species and why some invaders are so successful when responding to environmental change. We tested the morphology-performance relationship in the common wall lizard (Podarcis muralis), a small lizard species that has become established in urban Cincinnati. We measured climbing and clinging performance on different materials that mimic substrates that P. muralis is likely to encounter in nature. We performed every trial at two temperatures, 34º C and 24º C to test for the impact of temperature on performance. Each lizard was tested under two climbing conditions (cork and turf) at both temperatures each and tested on three clinging (cork, turf, and sandpaper) substrates with two temperatures each, for a total of 10 trials per individual lizard. We tested the influence of whole-organism morphology and claw size and shape on clinging and climbing performance. Claws from each lizard were then imaged with a Scanning Electron Microscope (SEM). Using geometric morphometrics, we extracted shape, curvature, and other dimensions from the SEM images of the lizard claws and tested the hypothesis that variation in claw morphology would impact climbing and clinging ability. This research will allow us to see the influence of body dimensions, claw shape and size, and temperature on performance. These results provide insight into how invasive species survive and even thrive in new environments, such as cities.