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Cities are focal points of introduction for invasive species. Urban evolution might facilitate the success of invasive species in recipient urban habitats. Here we test this hypothesis by rearing tadpoles of a successful amphibian urban coloniser and invader in a common garden environment. We compared growth rate, morphological traits, swimming performance, and developmental rate of guttural toad tadpoles (Sclerophrys gutturalis) from native rural, native urban, and non-native urban habitats. By measuring these traits across ontogeny, we were also able to compare divergence across different origins as the tadpoles develop. The tadpoles of non-native urban origin showed significantly slower developmental rate (e.g., the proportion of tadpoles reaching Gosner stage 31 or higher was lower at age 40 days) than tadpoles of native urban origin. Yet, tadpoles did not differ in growth rate or any morphological or performance trait examined, and none of these traits showed divergent ontogenetic changes between tadpoles of different origin. These findings suggest that prior adaptation to urban habitats in larval traits likely does not play an important role in facilitating the invasion success of guttural toads into other urban habitats. Instead, we suggest that evolutionary changes in larval traits after colonization (e.g., developmental rate), together with decoupling of other traits and phenotypic plasticity might explain how this species succeeded in colonising extra-limital urban habitats.

This article is currently in published at Behavioural Ecology and Sociobiology (https://doi.org/10.1007/s00265-021-03061-w).

This is the data and code for an article published in the Journal of Zoology (doi: 10.1111/jzo.12951)

Data and R code for the following research article from Urban Ecosystems: https://doi.org/10.1007/s11252-020-01065-4

Data and R code for the following research article from Biology Letters: http://dx.doi.org/10.1098/rsbl.2020.0651

One of the strongest driving forces of evolution is environmental change. Within the modern era, some of the most rapid environmental change has occurred as a result of urbanisation. As such, recent research aims to understand how species are adapting to urban landscapes (urban evolution) and how natural selection is operating in unnatural environments (anthropic selection). This goal was the cornerstone of my thesis research, using Australian water dragons (Intellagama lesueurii) to examine how the selective forces within urban environments may shape their natural histories and alter their evolutionary trajectory. I took a multidisciplinary approach to explore water dragon urban evolution, by examining traits related to their behavioural ecology (social interactions and spatial organisation, behavioural traits, and innate antipredator responses; Chapters I, II, & III respectively), morphology (body length and size; Chapter IV), and physiology (performance capacity; Chapters V & VI), using both field observations and laboratory experiments. The basis of most of this thesis' research involved contrasting traits of lizards living in, or originating from, populations varying in their levels of urbanisation (urban, semi-natural, and natural). I also examined the mechanisms that may have caused urban-derived divergence of morphological and behavioural traits (i.e., heritable traits vs phenotypic plasticity). My research identified several urban-derived divergent phenotypes, including increased rates of aggressive encounters, increased boldness, decreased body size paired with increased limb and head size, and decreased endurance capacity. My research also identified that both divergent behavioural (boldness) and morphological (body length and size) traits have a genetic origin, suggesting they are heritable and may be adaptive. Overall, this thesis provides insight into the urban evolution of water dragons in the Sydney region, and provides a framework for using a multidisciplinary approach to rigorously examine mechanistic urban ecology and evolution.