Evolutionary Origin and Maintenance of Sociality in the Small Carpenter Bees by Sandra M. Rehan, B. Sc. A Thesis submitted to the Department of Biological Sciences in partial fulfilment of the requirements for the degree of Doctor of Philosophy Brock University St. Catharines, Ontario © Sandra M. Rehan, 2011 TABLE OF CONTENTS TABLE OF CONTENTS ........................................................................................................... .i LIST OF TABLES ................................................................................................................... vii LIST OF FIGURES .................................................................................................................. .ix THESIS SUMMARY ............................................................................................................... xi ACKNOWLEDGEMENTS .................................................................................................... xiii OVERVIEW OF THESIS CONTENT................................................................................... xiv CHAPTER 1 General Introduction ................................................................. ,/............................................... 1 Part 1: Phylogenetic Contrasts and the Origins of Sociality...................................................... 1 Age and Phylogenetic Relationships in the Xylocopinae ............................................. .2 Social Behaviour of the Xylocopinae ........................................................................... ..4 Social Evolution of the Ceratinini .................................................................................. 6 Part 2: Evolutionary Explanations of Altruism.......................................................................... 7 Kin Selection and the Evolutionary Origin of Eusociality............................................ 8 Maternal Manipulation as an Amendment to Kin Selection........................................ 10 Ecological Constraints and Selection for Group Living .............................................. 12 Model Systems to Study Social Origins ....................................................................... 12 The Small Carpenter Bees ............................................................................................ 13 Research Aims .......................................................................................................................... 14 CHAPTER 2 Social polymorphism in the Australian small carpenter bee, Ceratina (Neoceratina) australensis ............................................................................................................................... 15 Introduction ............................................................................................................................. 16 Methods ................................................................................................................................... 18 ii Statistical Analyses ..................................................................................................... 20 Results ..................................................................................................................................... 20 Frequency of social nesting .......................................................................................... 20 Colony cycle .......................................................... ....................................................... 21 Maternal care and longevity......................................... ................................................ 22 Reproductive hierarchies in social colonies ................................................................ .23 Nest architecture and brood productivity ..................................................................... 26 Discussion ................................................................................................................................ 27 Maternal behaviour and social preadaptations ..............{ ............................................ 28 Female dispersal and social nesting ............................................................................. 29 Reproductive differentiation in social colonies ............................................................ 30 Brood productivity and social benefits ......................................................................... 32 Acknowledgments .................................................................................................................... 34 References ............................................................................................................................... 35 Tables 1 - 2 .............................................................................................................................. 39 Figures 1 - 4 .............................................................................................................................. 41 CHAPTER 3 Fitness consequences of ecological constraints and implications for the evolution of sociality in an incipiently social bee ....................................................................................................... 46 Introduction ............................................................................................................................. 47 Methods ................................................................................................................................... 50 Statistical Analyses ............................................................................. 52 Results ..................................................................................................................................... 53 Weather variation among brood rearing periods .......................................................... 53 Nest site availability.......................................... ........................................................... 53 iii Variation in brood development. .................................................................................. 54 Variation in reproductive success in solitary nests ...................................................... 55 Reproductive success in solitary versus social nests .................................... :............... 56 Discussion................................................................................................................................ 57 Environmental constraints on development rates and brood production ..................... 58 The effect of brood parasitism on reproductive success .............................................. 59 Nest substrate limitation and social nesting ................................................................. 60 Acknowledgments .................................................................................................................... 61 References ................................................................................ ,/............................................ 62 Table 1...................................................................................................................................... 68 Figures 1 - 4 .............................................................................................................................. 69 CHAPTER 4 The costs and benefits of sociality in a facultatively social bee ............................................... 74 Introduction ............................................................................................................................. 7 5 Methods ................................................................................................................................... 79 Life history ................................................................................................................... 79 Nest collections and brood production ......................................................................... 79 Relatedness estimates ........................................................................ ;.......................... 80 Results ..................................................................................................................................... 81 Brood productivity....................................................................................................... 81 Relatedness estimates ................................................................................................... 82 Direct fitness of solitary and social females ................................................................. 83 Inclusive fitness of solitary and social females ............................................................ 84 Discussion ................................................................................................................................ 85 iv Implications of dispersal for social potential... ............................................................ 86 Reproductive success and direct fitness ....................................................................... 87 Cooperative behaviour and indirect fitness .................................................................. 88 Conclusions .............................................................................................................................. 88 Acknowledgments ...................................................................................................................