The effect of urbanization on butterfly assemblages in Melbourne, Australia By Jessica S. Kurylo orcid.org/0000-0001-5864-7198 Submitted in total fulfilment of the requirements of the degree of Doctor of Philosophy School of Ecosystem and Forest Sciences Faculty of Science The University of Melbourne December 2017 1 Cover Photo*: 1 – Orange Palm Dart (Cephrenes augiades) 1 2 4 6 2 – Australian Painted Lady (Vanessa kershawi) 3 – Common Brown (Heteronympha merope) 4 – Common Grass Blue (Zizina otis labradus) 7 5 – Cabbage White (Pieris rapae) 5 6 – Yellow Admiral (Vanessa itea) 3 7 – Green Grass Dart (Ocybadistes walker) 8 8 – Imperial Hairstreak (Jalmenus evagoras) *All photos by J. Kurylo 2 Abstract Urbanization is the fastest expanding land-use conversion in the world. Alteration or loss of habitats in urban areas often results in overall biodiversity decline. Insects are integral components of ecosystems, providing important services such as decomposition and pollination. Despite this, we know little about the ecology of insects within urban settings. Butterflies are well suited for study in urban areas because they are conspicuous components of any landscape and play an important role within the ecosystem. To date, there has been a lack of understanding of the interplay between the ability of urban areas to provide necessary butterfly habitat resources (e.g., adult and larval food plants) and how the presence of those resources affects the butterfly community. Urban ecology studies are often entrenched in patch-matrix theory, but the use of a gradient paradigm allows for a more mechanistic understanding of the response of species and higher taxa to increasing urbanization. Therefore, this thesis uses a continuous gradient of imperviousness (percent cover of impervious surfaces) to assess how the urban landscape may support the local butterfly community through the availability of their required resources. This PhD first aimed to quantify the spatial variation in butterfly community structure across a gradient of imperviousness using two measures of habitat quality for adult butterflies and larval stages: native and non-native floral abundance and the availability of remnant vegetation. Approximately 21% of the region’s butterfly species were detected within the study area. Butterfly species richness and abundance and floral abundance declined with increasing imperviousness. The effects of total and native floral abundance measures on butterfly richness and abundance were small, but positive. The availability of remnant vegetation had a small, but positive influence on butterfly species richness. The second aim was to assess the response of larval host plants (LHPs) over the same imperviousness gradient. Laval host plant richness and cover decreased with increasing imperviousness, but LHP richness in particular had a significant, positive influence on butterfly richness and abundance. Larval host plant cover explained 57% of the variation i within part of the butterfly community. Common butterflies within the matrix had a significant relationship with some of their specific LHPs. The third aim was to determine if the local butterfly community derived any benefit from wildlife gardening (resource supplementation or management decisions to benefit wildlife) within urban areas. Comparisons of the butterfly communities across gardens managed for wildlife versus those that are not, revealed that garden type did not influence butterfly responses, but instead led to increased native floral resources in wildlife gardens. This study suggests the landscape context of wildlife gardens may play a role in their effectiveness. This work demonstrates that the landscape-scale alterations imposed by urbanization have a negative impact upon butterfly communities, and the adult and larval food resources they require. Increases in these resources had some positive effects, but these were mostly small and in some cases only benefitted common butterflies. Management programs aiming to increase habitat for butterflies in urban areas need to consider species-specific requirements and urban context in order to support urban butterfly communities. ii Declaration This is to certify that: 1) This thesis is my original work. 2) Due acknowledgement has been made in the text to all other material used. 3) This thesis is less than 80,000 words in length, exclusive of tables, figures, bibliographies, and appendices. __________________________________ Jessica S. Kurylo December 2017 iii Preface This PhD thesis consists of five chapters, one of which has been submitted for publication in an international peer-reviewed journal*. Jessica S. Kurylo designed the experiments, collected the data in the field, analysed the data, and wrote the thesis and manuscripts. Co-authors supervised or assisted with various stages of this PhD project and contributed in revising the following manuscript: Chapter 2 Kurylo, J.S., C.G. Threlfall, K.M. Parris, A. Ossola, N.S.G. Williams, and K.L. Evans. 20XX. Colourful wings in grey landscapes: Butterfly community structure along a gradient of imperviousness. Submitted to Landscape Ecology late Sept 2017. Results from this PhD have been presented at the following conferences: Kurylo, J.S., C. Threlfall, K. Evans, N.S. Williams. 2015. Do Floral Traits Explain Butterfly Use of Gardens in Urban Landscapes? Oral presentation at the Ecological Society of America Conference in Adelaide, SA. Kurylo, J.S., C. Threlfall, K. Evans, N.S. Williams. 2015. Colourful wings in a grey landscape: Butterfly species richness and abundance along an urban imperviousness gradient. Poster session at the Ecological Society of America Conference in Baltimore, Maryland, USA. Kurylo, J.S., C. Threlfall, K. Evans, N.S. Williams. 2015. Effect of Wildlife Gardens on Butterflies at Landscape and Garden Scales. Oral presentation at the International Association of Landscape Ecologists Conference in Portland, Oregon, USA. Additional conferences where data were presented, but not directly included in the PhD: Kurylo, J.S., C. Threlfall, K. Evans, N.S. Williams, K. Parris. 2017. Counting flowers in the ‘burbs: how floral richness and abundance changes along an imperviousness gradient. Oral presentation at the Victorian Biodiversity Conference, Melbourne, VIC. iv Kurylo, J.S., C. Threlfall, K. Evans, N.S. Williams, K. Parris. 2016. Counting flowers in the ‘burbs: how floral richness and abundance changes along an imperviousness gradient. Poster session at the Ecological Society of America Conference in Fremantle, WA. *Chapter 2 was submitted to an American journal; for consistency, the thesis has been written in American English. v Acknowledgements This PhD project was funded through several sources: Melbourne School of Land and Environment Student Awards 2014-2016; Frank Keenan Trust Fund Scholarships 2014 and 2015; and Dr. Nick Williams generously provided some funding in support of Chapter 3. I won a John Hodgson Scholarship in partial support of a lab visit with Dr. Karl Evans at the University of Sheffield, and an ESA Student Travel Grant in 2015; all conference travel was self-funded. I am grateful to have been supported during my candidature through the Melbourne International Research Scholarship (MIRS), Melbourne International Fee Remission Scholarship (MIFRS), and a studentship from the School of Ecosystem and Forest Sciences. I am grateful to my supervisors Drs. Kirsten Parris, Karl Evans, Nick Williams, and particularly Caragh Threlfall for whom I don’t have enough words to express the extent of my gratitude for her kindness, tutelage, and generosity of time over the last 4 years. Thanks to my panel, Drs. Chris Walsh and Tim New for your guidance and advice. Thanks also to Parks Victoria and to the many golf courses whom allowed me access. Many thanks to the Boroondara City Council, particularly Andrea Lomdahl, coordinator of the Backyard Biodiversity Program, for coordinating access to wildlife gardens participating in their program and to all the home owners whom allowed me access to their gardens. A great multitude of thanks to the Burnley Campus horticultural staff for tireless help with plant ID (John Rayner, Leanne Hanrahan, Dr. Susan Murphy, Jill Kellow, John Delpratt, Jenny Bear, Glenys Rose, and, in particular, Sascha Andrusiak for hours spent sitting through countless pictures of flowers). Helen Vickers, Linda Parker, and Jessica Baumann for sharing their respective plant knowledges. I thank Dr. Samantha Imberger for allowing me to use her lab and the administrative staff (Ross Payne, Vickie Mimis, and all the receptionists) for all the odds and ends they help us with. Thank-you to my amazing field assistants, John Delpratt and Linda Worland, for a job well done and field time well spent. To my friends and fellow students here in Melbourne, thank-you! Thank-you for conversations, smiles, support, meals, and knowledge shared. Most especially thank-you Sascha, Anne, Carola, Helen, Kate, and Zheng. To the academic staff members (Drs. Claire vi Farrell, Chris Szota, and Steve Livesley, in particular) whose ears I’ve bent on frustrating subjects, thank-you for your time and advice. I thank Hayley Lambert and Dr. Craig Nitschke for doing your jobs and helping me navigate a difficult situation. Thank-you to Dr. Dieter Houchuli and his Sydney University lab group for extending your warm hospitality to include me. To my former partner, thank-you. I would not have made it this far without the many conversations, knowledge, encouragement, ideas, adventures,