The evolution of the social and genetic mating system of purple-crowned fairy-wrens Malurus coronatus Dissertation zur Erlangung des akademischen Grades des Doktors der Naturwissenschaften (Dr. rer. Nat.) an der Universität Konstanz Mathematisch-Naturwissenschaftliche Sektion Fachbereich Biologie vorgelegt von Sjouke Anne Kingma Konstanz, 2011 Tag der mündlichen Prüfung: 20. July 2011 1. Referentin: Dr. Anne Peters 2. Referent: Prof. Dr. Martin Wikelski 3. Referent: Prof. Dr. Karl-Otto Rothhaupt 2 foar ús âlde lju 3 4 Purple-crowned fairy-wren, ‘Artist’s impression’ by Eke Mekkes “Charming as are many of Australian birds, I think the present species is entitled to the palm for elegance and beauty, not only among the members of its own genus, numerous and beautiful as they really are, but among all other groups of birds yet discovered; the charm, too, is considerably enhanced by the great novelty in the style of its colouring; for in how few birds do we find the lovely lilac tint which encircles and adorns the head of the bird!” John Gould in Birds of Australia , 1865 5 6 Table of contents Summary .............................................................................................................11 Zusammenfassung (German summary)........................................................13 Chapter 1. General introduction....................................................................17 Natural selection and reproductive strategies..............................................19 The evolution of extra-pair mating in birds ..................................................20 The evolution of cooperative breeding ...........................................................23 Extra-pair mating and cooperation ...............................................................26 Chapter 2. Radical loss of an extreme extra-pair mating system...........31 Abstract...........................................................................................................33 Introduction ....................................................................................................35 Methods...........................................................................................................37 Study species ...........................................................................................37 Comparing Malurus species ...................................................................39 Paternity analyses in M. coronatus ........................................................41 Results ............................................................................................................44 Extra-pair paternity................................................................................44 Adaptations to extra-pair mating: morphology and behaviour .............46 Comparing Malurus life-history and ecology .........................................48 Discussion .......................................................................................................49 Comparing Malurus life-history and ecology .........................................50 Conclusion ...............................................................................................53 Acknowledgements.........................................................................................53 Chapter 3. Female fairy-wrens synchronise egg laying to facilitate extra-pair mating for inbreeding avoidance...............................................55 Abstract...........................................................................................................57 Introduction ....................................................................................................59 Methods...........................................................................................................61 Study species and fieldwork ...................................................................61 Paternity analyses...................................................................................62 Relatedness..............................................................................................63 Analyses...................................................................................................63 Results ............................................................................................................66 Inbreeding depression and inbreeding avoidance by EG mating..........66 7 Ecological constraints on extra-group mating........................................67 Synchronisation by incestuously mated females ...................................68 Discussion .......................................................................................................71 Extra-group mating for inbreeding avoidance .......................................71 Synchronisation to overcome constraints on EG mating.......................72 Acknowledgements .........................................................................................74 Chapter 4. Multiple benefits drive helping behaviour in a cooperatively breeding bird: an integrated analysis ................................77 Abstract...........................................................................................................79 Introduction ....................................................................................................81 Methods...........................................................................................................84 Study site and species .............................................................................84 Relatedness and parentage.....................................................................84 Feeding watches ......................................................................................85 Analyses...................................................................................................85 Results.............................................................................................................88 Discussion .......................................................................................................93 Indirect and direct fitness benefits.........................................................93 Interacting hypotheses explain cooperation: implications ....................95 Acknowledgements .........................................................................................95 Chapter 5. Multiple benefits of cooperative breeding in purple- crowned fairy-wrens: a consequence of fidelity? .......................................97 Abstract...........................................................................................................99 Introduction ..................................................................................................101 Methods.........................................................................................................103 Study site and species ...........................................................................103 Population and nest monitoring ...........................................................103 Group size ..............................................................................................104 Nest observations ..................................................................................104 Statistical analyses ...............................................................................105 Comparative study ................................................................................108 Results...........................................................................................................111 Productivity ...........................................................................................111 Feeding rates .........................................................................................111 Comparative study ................................................................................115 Discussion .....................................................................................................118 Benefits of cooperative breeding in M. coronatus ................................118 The relative importance of compensatory and additive effects ...........119 Benefits of cooperative breeding: a role for extra-group mating? .......120 Conclusions............................................................................................120 Acknowledgements .......................................................................................121 8 Chapter 6. No evidence for offspring sex-ratio adjustment to social or environmental conditions in cooperatively breeding purple-crowned fairy-wrens........................................................................................................123 Abstract.........................................................................................................125 Introduction ..................................................................................................127 Methods.........................................................................................................130 Study species and field work ................................................................130 Nestling feeding watches ......................................................................131 Environmental conditions: food abundance, rainfall, and territory quality....................................................................................................131 Molecular sexing....................................................................................132