Patterns and potential mechanisms of phenotypic changes in urban small mammals

Urbanization is an example of human induced rapid environmental change (HIREC) that can have wide reaching ecological effects including habitat destruction, fragmentation, and alteration of local climates. Effects of urbanization have been shown to negatively impact wildlife as disturbances resulting from urbanization can create novel environments and selective pressures that could lead to changes in morphology, physiology, or both. We investigated how small mammal mass, length, and lipid levels vary along the urban rural gradient. These individuals are important to study as they are as prey animals, seed dispersers, have potential to transmit viruses and parasites to humans and human-commensal animals and are model organisms. We trapped small mammals at 23 sites along an urban-to-rural gradient centered in Atlanta, Georgia, USA from May-August 2023. For each individual, we recorded species, sex, reproductive status, body mass, total length, whole blood cholesterol (CHOL), triglycerides (TRIG), and high density lipoprotein cholesterol (HDL). We also recorded environmental variables such as temperature, ambient light, and plant cover. Body mass was modeled as an allometric function of length to calculate mass-length residuals (MLR) for each individual. We modeled physiological endpoints to assess the impact of environmental and anthropogenic factors associated with urbanization on animal morphology and health. Preliminary analyses suggest that TRIG and HDL are sensitive to urbanization, while CHOL and MLR are not. Total CHOL may be limited by MLR, but other blood endpoints are unrelated to MLR. Analysis is ongoing to clarify these relationships