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A University of Sussex DPhil thesis Available online via Sussex Research Online: http://sro.sussex.ac.uk/ This thesis is protected by copyright which belongs to the author. This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the Author The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the Author When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given Please visit Sussex Research Online for more information and further details Information gathering and conflict resolution in Polistes wasps Jonathan Philip Green Submitted for the degree of Doctor of Philosophy University of Sussex September 2011 ii Declaration The design and data collection for the study presented in Chapter 4 were undertaken in collaboration with Dr. Elli Leadbeater at the Institute of Zoology and Professor Jeremy Field at the University of Sussex. However, the particular analyses undertaken in that chapter, as well as the interpretations drawn from the data, are my own. I certify that, with the above qualification, the work carried out in this thesis is entirely my own, and that any help provided by other individuals with data collection and analysis is fully acknowledged. In addition, I certify that this thesis has not been, and will not be, submitted in whole or in part to another university for the award of any other degree. Signature: Jonathan Philip Green iii UNIVERISTY OF SUSSEX JONATHAN PHILIP GREEN, DOCTOR OF PHILOSOPHY INFORMATION GATHERING AND CONFLICT RESOLUTION IN POLISTES WASPS SUMMARY Signals are used to communicate resource-holding potential (RHP) to rivals during contests across a wide range of taxa. A controversial subset of RHP signals are status signals. In the last decade, research on North American populations of the paper wasp Polistes dominulus has provided evidence for a visual status signal based on variable clypeal patterns. However, observations of P. dominulus in its native European range indicate that the use of status signals across populations might be limited in this species. In Part I of this thesis (Chapters 3-5), I investigate status signalling in a Spanish population of P. dominulus. Using choice experiments, I show that clypeal patterns do not signal RHP in the Spanish population. Using large-scale field observations and microsatellite sequencing, I then show that patterns do not reflect individual quality in the wild. Together, these results strongly suggest that the clypeal pattern does not function in conflict resolution in the Spanish population. I conclude Part I by exploring the development of the clypeal patterns. I show that pattern expression is strongly temperature-dependent. This finding may provide an explanation for the variation in the signal value of clypeal patterns between populations. Contests among paper wasps are not limited to conspecific interactions, but may involve interactions with social parasites. In Parts II and III of this thesis (Chapters 6-7), I explore interactions between P. dominulus and the social parasite P. semenowi in the contexts of nest usurpation and conflict over reproduction. By experimentally staging usurpation contests, I show that neither parasites nor hosts gather information about rivals during nest usurpation. I then compare reproduction in parasitised and unparasitised colonies to test the predictions of competing models of reproductive skew. Incomplete control models receive qualified support; however, assumptions of skew models about players’ information gathering abilities are questioned. iv Publications arising from this thesis First-authored publications: Green, J. P. & Field, J. 2011. Assessment between species: information gathering in usurpation contests between a paper wasp and its social parasite. Animal Behaviour, 81, 1263-1269. Green, J. P. & Field, J. 2011. Inter-population variation in status signalling in the paper wasp Polistes dominulus. Animal Behaviour, 81, 205-209. In the course of my doctoral research, I have contributed to studies led by colleagues in the Social Evolution Research Group, which has resulted in shared authorship of the following papers: Leadbeater, E., Carruthers, J. M., Green, J. P., van Heusden, J. & Field, J. Unrelated helpers in a primitively eusocial wasp: is helping tailored towards direct fitness? Plos One, 5, e11997. Leadbeater, E., Carruthers, J. M., Green, J. P., Rosser, N. & Field, J. 2011. Nest inheritance is the missing source of direct fitness in a primitively eusocial insect. Science, 333, 874-876. Copies of all four publications are included at the end of this thesis as supporting material (see Appendix D). v Acknowledgements Many thanks are due first to my supervisor Jeremy Field for his guidance and support at all stages of my DPhil research. I am grateful to Jeremy in particular for his infectious enthusiasm and curiosity about evolution and natural history and for his rigorous approach to experimental design and analysis, which I hope is also catching. My sincere thanks also to other members of the Social Evolution Research Group at Sussex. Catherine Burton and Eric Lucas did much to help me settle in during my first year, and I thank them both for their kindness, generosity and excellent humour. Elli Leadbeater has been a wonderful friend and colleague during her time at Sussex. Elli has been unfailingly generous in offering guidance and help and has always been happy to give advice on any aspect of my work. Moreover, Elli’s resourcefulness and gift for organisation was of enormous benefit to me while on field work, while her vivacity and drive encouraged me to get the most out of my experience abroad. It has likewise been an absolute pleasure to work alongside Jon Carruthers, who is a true friend. Modest, funny and wise, Jon has kept me entertained while working tirelessly in the lab to assist with data collection. Finally, my thanks to Roger Schürch, who joined the group towards the end of my DPhil, thereby cleverly avoiding the majority of my questions, but has nonetheless graciously allowed me to pester him about statistical issues. To all in the Research Group, thank you. Elsewhere in Sussex, I have enjoyed the support, humour and good company of a number of people. Romain Blanc-Mathieu, Tomer Czaczkes, Adam Eyre-Walker, David Fisher Barham, Alan Hodgkinson, Lauren Holt, Sam Jones, Camilla Liscio, Eduardo Medina Bárcenas, Citlalli Morelos Juárez, Stephanie Murphy, Hannah Pratt, Lynne Robinson, Alan Stewart, Nina Stoletzki, Sam Valbonesi and Lucas Wilkins have all in their own way done much to make Sussex a stimulating and enjoyable place to work. I am also grateful to Tim Roper, who has been a wonderful second supervisor, generously providing help and advice when needed. My time at Sussex and my postgraduate experience has been enriched immeasurably through my friendship with Mike Clease and Sarah Zylinski. For all the lively discussion, adventures, Saturday Guardian crosswords and so much more besides I thank them. vi A number of people graciously gave their time to provide help with data collection and analysis, while others provided useful comments on drafts of the experimental chapters. Chapter 1. Jasper van Heusden provided several photographs for use in the figures. Chapter 2. Daniel Osorio generously provided the spectrometer and Sarah Zylinski provided technical support. Chapter 3. Rosie Foster and Elli Leadbeater assisted with data collection. Mark Briffa and Elizabeth Tibbetts provided critical feedback on a published version of the chapter. Chapter 4. Jon Carruthers, Jeremy Field, Elli Leadbeater, Thibault Lengronne and Neil Rosser assisted with data collection. Juan Miguel Mancera Romero and members of his lab generously provided storage facilities in Spain. Jon Carruthers and Jasper van Heusden assisted with DNA extraction and amplification of the microsatellites, and staff at the NERC Biomolecular Analysis Facility sequenced the microsatellites. Mike Clease helped with the image analysis. Eric Lucas and Lorenzo Zanette generously provided help with writing the simulations used in the data analysis. Elli Leadbeater provided useful comments on an earlier draft of the chapter. Chapter 5. Martyn Stenning and Julia Horwood provided technical support and Neil Crickmore and Elizabeth Hill kindly provided lab space. Charles Rose assisted with data collection and Naomi Ewald advised on data analysis. Tomer Czaczkes, Rosie Foster and Elli Leadbeater provided helpful comments on an earlier draft on the chapter. Chapter 6. Rosie Foster and Elli Leadbeater assisted with data collection. Elizabeth Tibbetts provided suggestions on an earlier version of the chapter, while Mark Briffa and Rob Elwood provided helpful feedback on a published version of the chapter. Chapter 7. Juan Miguel Mancera Romero and members of his lab provided storage facilities in Spain. Charlotte Aukett, Olga Drazan and Jeremy Field assisted with data collection. Edd Almond generously provided video footage. Jon Carruthers assisted with DNA extraction and amplification of the microsatellites, and staff at the NERC Biomolecular Analysis Facility sequenced the microsatellites. vii For helpful discussions and suggestions at various stages I also thank the following people: Margaret Couvillon, Innes Cuthill, Jon Endler, Richard Gill, Christoph Greuter, Simon Griffith, David Harper, Alexander Hayward, Marian Wong, Amotz Zahavi and Jelle van Zweden. Elsewhere, I am deeply grateful to Zoltan Ács and his family for hosting me during my fieldwork in Hungary, and for generously fuelling my wasp collecting trips with fantastic quantities of food and wine. Finally, I am deeply grateful to Rosie and to my family for their unwavering support and help at all stages of my DPhil. Rosie’s patience and understanding during the final stages of writing up, as well as her kindness, her generosity and her uniquely motivating style (‘Keep on writing! Keep on writing!’) have meant, and continue to mean, a great deal to me. My grandma and my sister have been wonderfully supportive throughout, and have always been there for a good chat.