University of New England The Thermal Games Dung Beetles Play A thesis submitted by Zac Hemmings, B. Environmental Science, B. Hons. Science Submitted for the award of Doctor of Philosophy 18/09/2018 TABLE OF CONTENTS TABLE OF CONTENTS ......................................................................................... i ABSTRACT .......................................................................................................... iv DECLARATION .................................................................................................viii ACKNOWLEDGEMENTS ................................................................................... ix LIST OF TABLES .................................................................................................. x LIST OF FIGURES .............................................................................................. xii GENERAL INTRODUCTION ............................................................................... 1 1.1 – Insects and climate change ......................................................................... 1 1.2 – Thermal biology ......................................................................................... 3 1.2.2 – Thermal tolerance ................................................................................ 6 1.2.3 – Metabolic rate...................................................................................... 7 1.2.4 – Plasticity.............................................................................................. 9 1.3 – Measuring thermal physiology ................................................................. 12 1.3.1 – Critical thermal limits ........................................................................ 12 1.3.2 – Thermal limit respirometry ................................................................ 14 1.4 - Dung Beetles ............................................................................................ 16 1.4.1 – Feeding ............................................................................................. 18 1.4.2 – Reproduction, nesting behaviour, and bi-parental care ....................... 19 1.4.3 – Ecosystem services provided by dung beetles .................................... 22 1.4.4 – The dung beetle fauna of Australia .................................................... 23 1.5 – Thesis Overview ...................................................................................... 25 WHERE HAVE WE BEEN AND WHERE ARE WE GOING? DUNG BEETLE RESEARCH ACROSS THE WORLD.................................................................. 28 2.1 – Abstract.................................................................................................... 28 2.2 – Introduction.............................................................................................. 30 2.2.1 – Why are dung beetles studied ............................................................ 31 2.2.2 – Interactions with the other fauna ........................................................ 32 2.2.3 – Aims.................................................................................................. 34 2.3 – Methods ................................................................................................... 35 2.3.1 – Literature selection and coding .......................................................... 35 2.3.2 – Network analysis ............................................................................... 41 i 2.4 – Results and Discussion ............................................................................. 43 2.4.1 – Temporal trends................................................................................. 43 2.4.2 – Network graphs and geographical trends ........................................... 49 2.4.3 – Functional groups and multispecies studies ........................................ 54 2.4.4 – Methodologies employed ................................................................... 60 2.4.5 – Traits/responses assessed ................................................................... 63 2.4.6 – Use of dung and non-dung resources ................................................. 68 2.4.7 – Conclusions ....................................................................................... 74 A COMPARATIVE ANALYSIS OF THE THERMAL TOLERANCE AND METABOLIC RATE OF DUNG BEETLES FROM A TEMPERATE PASTURE ECOSYSTEM IN AUSTRALIA .......................................................................... 76 3.1 – Abstract.................................................................................................... 76 3.2 – Introduction.............................................................................................. 78 3.3 – Methods ................................................................................................... 84 3.3.1 – Study animals and site ....................................................................... 84 3.3.2 – Respirometry ..................................................................................... 86 3.3.3 – Data extraction .................................................................................. 89 3.3.4 – Analysis ............................................................................................ 89 3.4 – Results ..................................................................................................... 91 3.4.1 – CTmin/max ............................................................................................ 91 -1 3.4.2 – V̇ CO2 ml h ....................................................................................... 94 3.4.3 – Thermal sensitivity ............................................................................ 94 3.5 – Discussion ................................................................................................ 97 3.7 – Appendix ............................................................................................... 109 THE EFFECTS OF TEMPERATURE ON THE PHYSIOLOGY AND NESTING BEHAVIOUR OF A TUNNELLING DUNG BEETLE, ONTHOPHAGUS BINODIS, AND ITS IMPLICATIONS FOR THE PROVISION OF ECOSYSTEM FUNCTION. ....................................................................................................... 113 4.1 – Abstract.................................................................................................. 113 4.2 – Introduction............................................................................................ 114 4.3 – Methods ................................................................................................. 119 4.3.1 – Study animals and site ..................................................................... 119 4.3.2 – Dung ............................................................................................... 119 4.3.3 – Chamber design ............................................................................... 120 ii 4.3.4 – Experimental design ........................................................................ 124 4.3.5 – Thermolimit respirometry ................................................................ 125 4.3.6 – Data extraction ................................................................................ 126 4.3.7 – Data analysis ................................................................................... 127 4.4 – Results ................................................................................................... 130 4.4.1 – CTmax............................................................................................... 130 4.4.2 – Metabolic rate and thermal sensitivity.............................................. 130 4.4.3 – Brood balls ...................................................................................... 131 4.5 – Discussion .............................................................................................. 137 4.5.1 – Thermal physiology ......................................................................... 137 4.5.2 – Brood Balls ..................................................................................... 140 4.5.3 – Conclusions ..................................................................................... 143 4.6 – Appendix ............................................................................................... 145 GENERAL DISCUSSION.................................................................................. 149 REFERENCES ................................................................................................... 155 iii ABSTRACT Dung beetles are a group of coprophagous scarabs most well known for their reliance on dung as both a source of food and as a vital component of their reproductive cycle. Intense competition between sympatric dung beetles species has spurred the evolution of a variety of complex nesting behaviours; telecoprids move dung along the soil surface; endocoprids reproduce within the dung itself; paracoprids bury dung in tunnels beneath the soil surface. The act of breaking down and relocating dung facilitates numerous biotic and abiotic processes that shape the environment and aid in maintaining ecosystem function. As a result of their ubiquity, the unique niche they inhabit, diverse range of species and life history strategies that have evolved, and strong ties to the biotic and abiotic processes in their surrounding habitat dung beetles have been the subject of research across the globe. We conducted a review of 1463 peer reviewed papers concerning