Seed dispersal and population genetic variation in the context of fire A case study on two plant species in fire-prone mallee in South Australia A thesis submitted in fulfilment of the requirements for the award of the degree DOCTOR OF PHILOSOPHY from FLINDERS UNIVERSITY by Bianca Dunker, MSc SCHOOL OF BIOLOGICAL SCIENCES August 2015 Table of Contents ABSTRACT ............................................................................................................................. V CERTIFICATION ................................................................................................................. VII ACKNOWLEDGEMENTS .................................................................................................. VIII PREFACE ................................................................................................................................ X CHAPTER ONE ...................................................................................................................... 1 Introduction - Fire and the importance of seed dispersal for population connectivity 1.1 Fire in the Australian ecosystem as a natural occurrence .............................................. 2 1.2 Fire in Australian ecosystems as a management tool ..................................................... 2 1.3 Fire regime changes and their potential effect on biotas ................................................ 3 1.4 Importance of dispersal .................................................................................................. 6 1.5 Parameters that influence seed dispersal distances by wind .......................................... 6 1.6 Population genetics in fire-prone vegetation ................................................................. 8 1.7 Aim of this study ............................................................................................................ 9 1.8 Study system and species ............................................................................................... 9 1.8.1 Study system and its past and present fire regimes ................................................. 9 1.8.2 Ecology and dispersal features Triodia ................................................................. 12 1.8.3 Ecology and dispersal features Callitris verrucosa .............................................. 14 1.9 Thesis outline ............................................................................................................... 16 1.10 References .................................................................................................................. 17 CHAPTER TWO ................................................................................................................... 24 A comprehensive approach to assess seed dispersal of two plant species in mallee 2.1 Abstract ........................................................................................................................ 26 2.2 Introduction .................................................................................................................. 28 2.3 Material and methods ................................................................................................... 31 2.3.1 Study region .......................................................................................................... 31 2.3.2 Ecology of study species ....................................................................................... 31 2.3.3 Direct tracking of seed dispersal ........................................................................... 33 2.3.4 Mechanistic seed dispersal .................................................................................... 36 2.3.5 Indirect genetic estimate of dispersal .................................................................... 38 2.4. Analysis....................................................................................................................... 39 2.5 Results .......................................................................................................................... 41 I 2.5.1 Triodia irritans ...................................................................................................... 41 2.5.2 Callitris verrucosa ................................................................................................ 44 2.6 Discussion .................................................................................................................... 47 2.6.1 Triodia irritans ...................................................................................................... 48 2.6.2 Callitris verrucosa ................................................................................................ 49 2.6.3 Direct tracking ...................................................................................................... 50 2.6.4 Mechanistic model ................................................................................................ 50 2.6.5 Genetics ................................................................................................................. 51 2.6.6 Conclusion ............................................................................................................ 52 2.7 Acknowledgements ...................................................................................................... 52 2.8 References .................................................................................................................... 53 2.9 Supplementary Materials: ............................................................................................ 58 CHAPTER THREE ............................................................................................................... 59 Exploring population genetic diversity and structure of Triodia irritans under various fire regimes 3.1 Abstract ........................................................................................................................ 61 3.2 Introduction .................................................................................................................. 62 3.3 Methods........................................................................................................................ 66 3.3.1 Study region .......................................................................................................... 66 3.3.2 The study species .................................................................................................. 67 3.3.3 Data collection ...................................................................................................... 68 3.3.4 Microsatellites ....................................................................................................... 70 3.3.5 Plant characteristics............................................................................................... 72 3.3.6 Microsatellite loci and estimation of ploidy .......................................................... 72 3.3.7 Genetic Diversity and clonality ............................................................................. 73 3.3.8 Spatial genetic structure ........................................................................................ 73 3.4 Results .......................................................................................................................... 74 3.4.1 Plant characteristics............................................................................................... 74 3.4.2 Estimation of ploidy .............................................................................................. 76 3.4.3 Genetic diversity and clonality ............................................................................. 76 3.4.4 Spatial Genetic Structure ...................................................................................... 78 3.5 Discussion .................................................................................................................... 83 3.6 Acknowledgements ...................................................................................................... 86 3.7 References .................................................................................................................... 87 3.8 Supplementary Materials: ............................................................................................ 92 II CHAPTER FOUR .................................................................................................................. 93 Low genetic diversity of Callitris verrucosa in mallee vegetation 4.1 Abstract ........................................................................................................................ 95 4.2 Introduction .................................................................................................................. 96 4.3 Material and methods ................................................................................................... 99 4.3.1 Study region .......................................................................................................... 99 4.3.2 Study species ......................................................................................................... 99 4.3.3 Sample collection ................................................................................................ 100 4.3.4 Genetics ............................................................................................................... 101 4.3.5 Data analyses