ResearchOnline@JCU This file is part of the following reference: Barnett, Louise Katherine (2017) Understanding range expansion of Asian house geckos (Hemidactylus frenatus) in natural environments. PhD thesis, James Cook University. Access to this file is available from: http://researchonline.jcu.edu.au/51755/ The author has certified to JCU that they have made a reasonable effort to gain permission and acknowledge the owner of any third party copyright material included in this document. If you believe that this is not the case, please contact [email protected] and quote http://researchonline.jcu.edu.au/51755/ Understanding range expansion of Asian house geckos (Hemidactylus frenatus) in natural environments Thesis submitted by Louise Katherine Barnett BSc (Hons) October 2016 Revised thesis submitted March 2017 For the degree of Doctor of Philosophy College of Science and Engineering James Cook University Townsville, Queensland 4811 Australia i Front cover: Asian house gecko (Hemidactylus frenatus). Photo by Stephen Zozaya. ii Acknowledgements This project has been a huge challenge for me, but it has also been an awesome adventure, largely due to the wonderful people I met and worked with along the way. Firstly, an enormous thank you to my advisors Conrad Hoskin and Ben Phillips for your guidance, encouragement, support and feedback throughout the entire project. I couldn’t have done it without you. Conrad, thank you for taking me under your wing and giving me a glimpse of how an expert herpetologist works. Without your training there may not have been any geckos featured in this thesis! Ben, thank you so much for introducing me to the wonderful world of R, and for imparting some of your stats- wizardry. I have a long way to go, but I am definitely hooked. This project involved a lot of fieldwork and would not have been possible without all the volunteers and friends who braved mosquitoes, stray dogs and brown snakes to search for geckos with me. A massive thank you to: James Murray, Maddie Wuth, Margaret Murray, Michael Lee, Stewart Macdonald, Sheryn Brodie, Kelsey Hosking, Stephen Zozaya, Roderick Budd, Kirilly O’Reilly, Dylan Tegtmeier, Kyana Pike, Nantida Sutummawong, Theresa Rüger, Nadiah Roslan, Matthew McIntosh, Legana Fingerhut, Yan Ow, Tiffany Sih, Steven Johnson, Lauren Heilbronn, Jen Atherton, Hector Barrios, Eric Nordberg, Mat Vickers, Seun-Jin Hong, Natalie Wildermann, Kelsey Miller, Jenna Wanamaker, Isabel Ender, Gina Barnett, Eric Vanderduys, April Reside, Betsy Roznik, Amy Thompson, Rebecca Exl, Alana Trott, Helios Martinez, Russell Stanford and Abigail Nelson. iii Thanks to Andrew Coates for being an excellent ‘parasite buddy’ in the field and lab, and to Megan Higgie and Allen Heath for your expert advice and collaboration on papers. Thanks also to the members of the Adaptation Lab and the Centre for Tropical Biodiversity and Climate Change for your feedback on seminar presentations and moral support. To my officemates, especially Stewart Macdonald, Stephen Zozaya, Nantida Sutummawong and Nadiah Roslan, thank you for the fun times herping, the coffee breaks, the pancake parties, the chocolate eating and the Miley Cyrus-ing. Also, thanks Stephen for letting me use your photos in this thesis. To my other wonderful friends/second family in Townsville, thanks for your friendship, laughter and for making it feel like home. To my actual family, especially my mum, dad, and Sam – thank you for your unwavering encouragement, support and belief in me. Last, but most definitely not least, to James Murray, thank you for being the best. Louise Barnett October 27 2016 iv Publications associated with thesis This thesis has been prepared as a series of manuscripts that have either been published or prepared for publication. Each manuscript has been formatted in the style of the target journal. This thesis also includes an Introduction (Chapter 1) and a Thesis Summary (Chapter 6). The below table provides details of author contributions for each manuscript. Chapter Publication Status Statement of authorship Barnett, L.K., B.L. Phillips and C.J. LKB collected the data. LKB, CJH and BLP Hoskin (2016) Going feral: Time conceived the analyses. LKB performed the and propagule pressure determine analyses. LKB wrote the manuscript. CJH and 2 Published range expansion of Asian house BLP edited the manuscript. All authors geckos into natural environments. contributed to ideas and revisions. Austral Ecology Barnett, L.K., M. Higgie, B.L. LKB collected the data. LKB, MH and CJH Phillips and C.J. Hoskin (in prep) conceived the analyses. LKB performed the Morphological divergence in In analyses. LKB wrote the manuscript. CJH, 3 woodland populations of a human- preparation BLP and MH edited the manuscript. All associated invasive gecko. authors contributed substantially to ideas and Biological Invasions revisions. Barnett, L.K., B.L. Phillips, A. LKB conducted the surveys. LKB, AC and Heath, A. Coates and C.J. Hoskin CJH collected specimens, AH identified the (in prep) Host specificity and the In specimens. LKB, CJH and BLP conceived the 4 potential impact of parasites during preparation analyses. LKB conducted the analyses. LKB range expansion of an invasive wrote the manuscript. CJH, BLP, AH and AC gecko. OIKOS edited the manuscript. Barnett, L.K., C.J. Hoskin and B.L. LKB collected the data. BLP conceived the Phillips (in prep) Modeling analyses. LKB performed the analyses. LKB individual-level detection In wrote the paper. CJH and BLP edited the 5 probability of invasive Asian house preparation paper. All authors contributed substantially to geckos in natural environments ideas and revisions. Biological Invasions v Statement of contribution of others Research funding and stipend • Australian Postgraduate Award • Australian Geographic • James Cook University Centre for Tropical Biodiversity and Climate Change Supervision • Dr Conrad Hoskin, Centre for Tropical Biodiversity and Climate Change, JCU • Dr Ben Phillips, Centre for Tropical Biodiversity and Climate Change, JCU & University of Melbourne Co-authorship of published manuscripts Co-authors of published manuscripts within this thesis participated in one or more of the following ways: discussions of concept and study design, advice on methods and editing of manuscripts, collation and/or generation of data. Every reasonable effort has been made to gain permission and acknowledge the owners of copyright material. I would be pleased to hear from any copyright owner who has been omitted or incorrectly acknowledged. Animal ethics statement The research presented and reported in this thesis was conducted in compliance with the National Health and Medical Research Council (NHMRC) Australian Code of Practice for the Care and Use of Animals for Scientific Purposes, 7th Edition, 2004 and the Qld Animal Care and Protection Act, 2001. The proposed research study received animal ethics approval from the JCU Animal Ethics Committee (approval number A1801). vi Abstract Over the past 50 years accidental introductions of invasive species have accelerated due to globalisation and increased transit efficiency. Once established, invasive species may affect biodiversity through predation, competition or hybridisation with native taxa, or through the introduction of novel parasites. The impacts of invasive species are mediated by their distribution within the introduced range, and it is important to understand the processes controlling range expansion of invasive species. Human- associated invasive species are often overlooked as potential threats to native species in natural environments, due to their perceived restriction to anthropogenic habitats. It is, nonetheless, likely that some of these species will eventually spread into natural habitats due to their broad global distributions, propensity to establish large populations in urban areas and the ever-expanding reach of human infrastructure. Human-associated species also present ideal systems to assess the factors driving range expansion across abrupt ecological boundaries because of the stark differences between urban areas and surrounding natural environments, and because urban areas often provide multiple semi- independent invasion fronts to compare within the same geographic region. This thesis investigates the factors that facilitate range expansion of a human-associated invasive species, the Asian house gecko, Hemidactylus frenatus, into natural habitats in the Townsville region of northern Australia. It outlines how demographic factors, environmental factors, morphological divergence and parasitism affect range expansion, touches on the potential impacts of H. frenatus in these environments and establishes an effective method for H. frenatus detection. vii Chapter 2 investigates whether there are established populations of H. frenatus in natural environments, and assesses whether environmental or demographic factors affect expansion into natural habitats. This was achieved by surveying ten transects in the Townsville region of north Queensland every month for a year. Each transect was made up of five sites positioned every 500 m from the urban edge up to 2 km into surrounding woodland. This work revealed that the most important factors facilitating expansion into woodland environments are propagule pressure (i.e., relative abundance of H. frenatus at the urban edge) and the number of years since H. frenatus established in the urban area. Environmental factors, such as coarse habitat structure and size of the urban area did