The Physiological Adaptations of Podarcis muralis in Urbanized Localities

Students: Princeton Vaughn ’22, Wyatt McQueen ’22, Sierra Spears ’22, Ciara Pettit ’23, and Caitlyn Colwell ’21
Research Mentors: Eric Gangloff and Laura Tuhela-Reuning (OWU Department of Biological Sciences)

When urbanization occurs, many factors can challenge organisms: introduction of humans, altered food webs, human-made habitats, and exposure to new urbanized predators. For our study, we focused on an invasive species of lizard in urban Cincinnati, Ohio, known as the Common Wall Lizard (Podarcis muralis). We collected blood from adult male, gravid female, and non gravid female lizards, and quantified 3 physiological markers found within the blood plasma: corticosterone, glucose, and triglyceride. Corticosterone is a hormone that correlates with stress and energy balance, glucose is a carbohydrate that is the main source of energy throughout the body in the form of sugar, and triglyceride is a fat (or lipid) that is utilized for long-term energy storage. Together, these markers can help us characterize physiological differences among groups of lizards, distinguish what could cause these differences, and identify how a species like Podarcis mualis is able to thrive in highly urbanized environments versus other relative species.

Urbanization plays an impactful role in the survival of organisms, biodiversity, and the quality of an environment. Many species of organisms are driven out of localities when ecosystems are altered or destroyed. In some instances, animals have adapted to these significant changes and can successfully coexist in urbanized environments and anthropogenic structures. A small species of lizard known as the Common Wall Lizard (Podarcis muralis) was introduced into urban areas of Cincinnati, Ohio in the 1950s. For our experiment, we are interested in determining how Podarcis physiologically adapt to the conditions of urbanization. We collected data on lizards from five different sites around Cincinnati: two city parks and three roadside walls (51 males, 32 gravid females, and 8 non-gravid females). We collected blood samples with glass capillary tubes in the right post-orbital sinus (~30 μL per individual). We will measure corticosterone, glucose, and triglyceride found in the plasma, which serve as excellent markers for stress, energy, and stored available energy. This work continues research from last academic year when our protocols were validated to measure each of these physiological indicators in small amounts of blood. We hypothesize that gravid females will have higher levels of corticosterone due to the process of gestation. We also hypothesize that lizards will have higher levels of glucose and triglycerides in more open environments due to the need to escape from threats. With our findings, we can identify how these physiological markers vary based on the sex and locations of lizards, and how this variation affects survival and reproduction.