Urbanization, Metabolic Rate, and Body Size Variation of a Common Urban Lizard

AbstractHuman-induced rapid environmental change is intensifying globally. Urbanization, a major form of human-induced rapid environmental change, alters ecosystems and exposes wildlife to environmental changes, including pollution, altered ambient temperatures, changes in habitat structure, and resource shifts. These alterations can benefit particular species while imposing challenges to others, influencing their behavior, physiology, and morphology. Changes in resource availability and ambient temperature are particularly relevant for ectotherms, which are less independent of environmental conditions than endotherms for thermoregulatory behavior and physical activity. To date, physiological and morphological responses have been less well studied than behavioral responses to urban environments in ectotherms. In this study, we measured standard metabolic rate ([Formula: see text]) of common wall lizards (Podarcis muralis) inhabiting habitats that differ in the degree of urbanization (as measured by impervious surface area). Over a period of 4 yr, we also recorded body size (mass and snout-vent length) of lizards from urban ([Formula: see text]) and nonurban ([Formula: see text]) habitats. Standard metabolic rate did not differ between urban and nonurban habitats or with degree of urbanization. While females showed no habitat-associated differences in any trait, males from urban habitats exhibit a reduced body mass and shorter snout-vent length than their nonurban counterparts. Despite these differences, body condition did not vary between the two habitat types. These findings indicate that although sex-specific patterns in body mass and length occur, standard metabolic rate does not vary with urbanization. This underlines the importance of studying physiological and morphological traits of both sexes to better understand the impact of urbanization on wildlife.