Urbanization and the common wall lizard (Podarcis muralis) in the Pannonian basin, Serbia: nowhere safe? T. Vukov 1 , M. Mir c 1 , N. Toma sevi c Kolarov 1 & S. Stamenkovi c 2 1 Department of Evolutionary Biology, Institute for Biological Research ‘Sini sa Stankovi c’, University of Belgrade, Belgrade, Serbia 2 Faculty of Biology, University of Belgrade, Belgrade, Serbia Keywords environmental stress; developmental instability; geometric morphometrics; modularity; integration; allometry; phenodeviants; urban ecology. Correspondence Tanja Vukov, Department of Evolutionary Biology, Institute for Biological Research ‘Sini sa Stankovi c’, University of Belgrade, Bulevar despota Stefana 142, Belgrade, Serbia. Email: tvukov@ibiss.bg.ac.rs Editor: Mark-Oliver R€ odel Received 19 February 2019; revised 19 August 2019; accepted 21 August 2019 doi:10.1111/jzo.12735 Abstract Numerous studies of urban environment impact on wildlife imply urbanization can have both negative and positive effects. Phenotypic variation of pileus in the com- mon wall lizard (Podarcis muralis) was analysed to determine whether urbanization levels can be associated with developmental instability induced by environmental stress. Pileus developmental pathways and instability in natural, suburban and urban populations were quantified by patterns of size and shape, fluctuating asym- metry (FA), modular organization and integration, allometric trajectories and fre- quency of phenodeviants. Our results show high asymmetry and modular structure of pileus with the high frequency of phenodeviants for natural, suburban and urban populations indicating elevated developmental instability in all three habitat types. However, some peculiarities were observed comparing habitats – the lowest level of FA and integration in urban populations and unexpectedly high level of FA and frequency of phenodeviants in the natural population. In addition, significant corre- lations between symmetric and asymmetric shape patterns, and presence of modular organization for all three habitat types suggest that genetic/environmental and developmental parcellation are somewhat aligned. Our results indicate that pileus morphology varies in a complex manner and future studies that link physiological, behavioural and morphological parameters to demographic parameters and fitness are necessary to fully understand how environmental stress affects developmental instability. Introduction The most important human-induced environmental changes are habitat loss/fragmentation, the spread of exotic species, harvest- ing by humans, different kind of pollution and climate change (Sih, Ferrari & Harris, 2011). Urbanization has a key role in habitat loss, degradation and fragmentation as infrastructure reduces aquatic and terrestrial habitats and impedes movement of terrestrial species thus reducing their viability (Clevenger & Wierzchowski, 2006). Some of the consequences of urbaniza- tion are contamination of water and land (e.g. with pesticides, oils, heavy metals) (Burger & Gochfeld, 2004), change in the water regimes of wetlands and rivers (Lee et al., 2006), intro- duction of non-native predators (Baker et al., 2008), warmer ambient temperatures (McLean et al., 2005), a disruption of light/dark cycles (Klem, 2007), increased noise (Perry et al., 2008) and increased disturbance by humans (Markovchick- Nicholls et al., 2008). As environmental changes due to urban- ization are usually rapid and drastic, many species cannot adapt that fast and their tolerance limits are exceeded (Sih et al., 2011), leading to the reduction of species richness (McKinney, 2008), presumably by accelerating local extinction rates. However, some species find good opportunities for range expansion into urban areas, both invasive species that expand beyond their native range (Pimentel, Zuniga & Morrison, 2005), as well as species native for the region (Shochat et al., 2006). Such species alter their life histories in many ways compared with their native habitats, including decreased home ranges, higher densities, changes in foraging tactics, increased reproductive output traits, etc. (Shochat et al., 2006) in order to cope with new environments. Birds and mammals are groups that are the most studied in efforts to gain insight into the abilities of animals to adapt to urban habitats (Ordenana et al., 2010). However, more attention should be given to other animal groups as the effects of urbanization likely vary sub- stantially across taxonomic groups due to differences in disper- sal, habitat, ecology, physiology and life-history traits. The studies of reptiles in urban environment were focused on abundance and spread of invasive species (Gibbons et al., 2000), impact of landscape changes and habitat fragmentation on native fauna species richness (e.g. Mollov et al., 2009; Kolbe et al., 2016). Further, studies of reptiles in urban areas investigated impacts of biotic factors like human presence (Teixeira et al., 2016), diet changes (Wolfe, Bateman & Flem- ing, 2017), parasite loads (Lazi  c et al., 2017a), as well as Journal of Zoology  (2019) – ª 2019 The Zoological Society of London 1 Journal of Zoology. Print ISSN 0952-8369