Shrinking into the big city: influence of genetic and environmental factors on urban dragon lizard morphology and perfor

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Shrinking into the big city: influence of genetic and environmental factors on urban dragon lizard morphology and performance capacity James Baxter-Gilbert 1,2

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Julia L. Riley 1,3,4

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Celine H. Frère 5

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Martin J. Whiting 1

Accepted: 29 September 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract Urban wildlife faces a novel set of challenges resulting in selective pressure that can lead to population-level changes. We studied Australian water dragons (Intellagama lesueurii) from urban and natural populations to test if urban populations differed in body size, shape, and performance capacity. If urban-derived morphology has arisen through selection, we predicted distinct morphological differences between wild dragons from urban and natural areas in both adult and hatchling life-stages. Urban hatchlings were morphologically distinct (shorter body lengths and longer limbs) from natural populations, while urban adult males continued this trend but only for body size (shorter body lengths). We then experimentally reared hatchlings originating from urban and natural populations within urban- and natural-style enclosures (2 × 2 factorial design) for a year to determine if differences in morphology and performance capacity (sprint speed, endurance, and clinging ability) were related to either the individual’s origin population or developmental environment. Yearlings reared in urban-style enclosures, irrespective of population origin, had smaller body sizes compared to those from natural-style enclosures, suggesting developmental environment was affecting their morphology. Despite this difference in body size, yearling dragon performance capacity was not significantly different between treatments. Overall, this study provides evidence of a complex relationship driving urban-divergent morphology – whereby urban dragons emerge as smaller hatchlings with longer limbs (innate traits) and are then further influenced by the urban environments that they develop in (phenotypic plasticity); however, and potentially owing to behavioral, ecological, and demographical differences, these changes appear to be sex-specific. Keywords Adaptation . HIREC . Natural selection . Phenotypic change . Phenotypic plasticity . Reptile . Urban evolution

Introduction Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11252-020-01065-4) contains supplementary material, which is available to authorized users. * James Baxter-Gilbert [email protected] 1

Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia

2

Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape 7600, South Africa

3

Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape 7600, South Africa

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Present address: Department of Biology, Dalhousie University, Halifax B3H 4R2, Canada

5

School of Science and Engineering, University of the Sunshine Coast, S