The Invasion Ecology of Common Wall Lizard (Podarcis Muralis): Population Dynamics, Interactions and Adaptations

The potentially damaging outcomes of species introductions to areas outside of their natural range are well known, and invasive non-native species are regarded as one of the most significant threats to biodiversity worldwide. Social perceptions of non-native species are open to subjective influence, and in a rapidly changing world the implications of species introductions are becoming less defined. Understanding the ecology of invasions and the human perceptions of them, is therefore fundamentally important for managing all stages of species introductions, relying on a multidisciplinary approach to understanding the invasion process. Invasions can also provide opportunities to study adaptive responses of organisms to novel or changing environments, which in turn can provide insight into mechanistic workings of the invasion process and range expansion. In this study I investigate the ecology of introduced populations of the Common Wall lizard (Podarcis muralis). Using a multidisciplinary approach including population ecology, functional ecology, predictive modelling, social science, and behavioural experiments, I focus on the species’ invasion potential, adaptive responses, and implications for ecological impacts on native lizards in the UK and on Vancouver Island, British Columbia. I found that morphological differences between populations were associated with ancestral origins and infer a greater invasion potential for animals of Italian origin over French. Comparison of physical and performance traits, and a broad dietary niche of P. muralis, indicate considerable overlap between P. muralis and native lizards, suggesting high potential for competitive interaction. However, the varied behavioural responses observed towards scent cues in P. muralis and native lizards suggests an interplay between naivety and threat sensitivity may influence interspecific interaction. Models of predicted range expansion suggest P. muralis populations are likely to remain localised, but that potential for secondary translocation is likely to increase with increasing population size, particularly in urban habitats. I also found clear indication that charismatic non-native species such as P. muralis, may have use as model species with which to raise awareness and minimise the subjectivity shaping perceptions of invasive species in general.