The impact of intraspecific predation on individual fitness and population viability Thesis submitted in accordance with the requirements of the University of Liverpool for the degree of Doctor in Philosophy by Adam Matthew Fisher. September 2019 1 CONTENTS ACKNOWLEDGEMENTS ............................................................................................................ 5 PREFACE ................................................................................................................................... 6 INTRODUCTION: Predatory cannibalism and its effect on small or sparse populations ......... 7 Box 1 - Correlated cues .................................................................................................. 10 Nutrient availability ........................................................................................................... 11 Mate quality ....................................................................................................................... 13 Size asymmetry .................................................................................................................. 15 Relatedness ........................................................................................................................ 16 Aggressive spillover ............................................................................................................ 19 Conclusions ........................................................................................................................ 20 CHAPTER 1: Sexual cannibalism and population viability ...................................................... 22 Abstract .............................................................................................................................. 22 Introduction ....................................................................................................................... 23 Methods ............................................................................................................................. 25 Mathematical model ...................................................................................................... 25 Stochastic model ............................................................................................................ 27 Results ................................................................................................................................ 28 Sexual cannibalism and population growth rate ........................................................... 29 Pre- versus post-copulatory cannibalism ....................................................................... 31 Discussion........................................................................................................................... 33 When does sexual cannibalism increase the productivity of a population? ................. 33 When is sexual cannibalism likely to be detrimental to population survival?............... 36 Supporting material ........................................................................................................... 38 CHAPTER 2: Mate-finding Allee effects can be exacerbated or relieved by sexual cannibalism ............................................................................................................................ 40 Abstract .............................................................................................................................. 40 Introduction ....................................................................................................................... 41 Methods ............................................................................................................................. 44 Results ................................................................................................................................ 48 Intra-seasonal dynamics ................................................................................................ 48 Founder population size ................................................................................................ 49 Mate encounter rate ...................................................................................................... 51 Discussion........................................................................................................................... 54 CHAPTER 3: Density-dependent aggression, courtship and sex ratio in the fishing spider Dolomedes fimbriatus ............................................................................................................ 61 2 Abstract .............................................................................................................................. 61 Introduction ....................................................................................................................... 62 Methods ............................................................................................................................. 64 Recording, collection and rearing .................................................................................. 64 Behavioural trials ........................................................................................................... 65 Statistical analyses ......................................................................................................... 66 Results ................................................................................................................................ 67 Discussion........................................................................................................................... 69 CHAPTER 4: The impact of behavioural syndromes on aggression in praying mantids ........ 74 Abstract .............................................................................................................................. 74 Introduction ....................................................................................................................... 74 Methods ............................................................................................................................. 78 Study species .................................................................................................................. 78 Aggression towards prey................................................................................................ 78 Aggression towards potential mates ............................................................................. 79 Analyses ......................................................................................................................... 80 Results ................................................................................................................................ 81 Miomantis caffra aggression ......................................................................................... 81 Orthodera novaezealandiae aggression ........................................................................ 82 Comparison of aggression of both species .................................................................... 84 Repeatability .................................................................................................................. 85 Body mass ...................................................................................................................... 86 Discussion........................................................................................................................... 88 Conclusions .................................................................................................................... 92 CHAPTER 5: Kin recognition mediates the effect of density and starvation on cannibalism rate ......................................................................................................................................... 94 Abstract .............................................................................................................................. 94 Introduction ....................................................................................................................... 95 Methods ............................................................................................................................. 97 Rearing, treatments and measurements ....................................................................... 97 Statistical analyses ....................................................................................................... 100 Results .............................................................................................................................. 101 Discussion......................................................................................................................... 104 Supporting material ......................................................................................................... 109 GENERAL DISCUSSION .......................................................................................................... 112 Theoretical findings ...................................................................................................... 113 3 Experimental findings .................................................................................................. 115 Conclusions .................................................................................................................. 118 REFERENCES ........................................................................................................................