Mistletoe effects on acacia species in western Saudi Arabia Dhafer Albakre Thesis submitted for the degree of a Doctor of Philosophy School of Biological Sciences The University of Adelaide South Australia April 2019 Table of Contents Declaration ......................................................................................................................................................... 3 Acknowledgments .............................................................................................................................................. 4 Abstract .............................................................................................................................................................. 7 Chapter 1: General introduction ..................................................................................................................... 11 Identification of mistletoes ............................................................................................................. 13 Life history .................................................................................................................................... 13 The effects of mistletoes on their hosts ........................................................................................... 14 Physiological effects ...................................................................................................................... 17 Effects on individuals ..................................................................................................................... 20 Effects on populations and communities ......................................................................................... 21 Research motivation and context .................................................................................................... 23 Research questions ......................................................................................................................... 26 Thesis structure .............................................................................................................................. 28 References ..................................................................................................................................... 29 Statement of Authorship ................................................................................................................................... 34 Chapter 2: Incidence and abundance of Mistletoes as a function of altitude and host characteristics in desert landscapes in the western Arabian Peninsula.................................................................................................. 35 Introduction ................................................................................................................................... 37 Results ........................................................................................................................................... 44 Discussion...................................................................................................................................... 47 Conclusion ..................................................................................................................................... 52 References ..................................................................................................................................... 54 Tables ............................................................................................................................................ 56 Figures ........................................................................................................................................... 60 Statement of Authorship ................................................................................................................................... 72 Chapter 3: The effect of mistletoes on the nutrient status of their hosts: investigating several patterns of infestation in the western Arabian Peninsula .................................................................................................. 73 Abstract ......................................................................................................................................... 73 Introduction ................................................................................................................................... 75 Statistical analysis .......................................................................................................................... 80 Results ........................................................................................................................................... 82 Discussion...................................................................................................................................... 86 Conclusion ..................................................................................................................................... 90 References ..................................................................................................................................... 91 Table .............................................................................................................................................. 93 Figures ........................................................................................................................................... 94 1 Statement of Authorship ..................................................................................................................................103 Chapter 4: Host–mistletoe interactions on a branch scale: Investigating the nutritional relationship under coexistence of three mistletoe species on a single host tree, Vachellia gerrardii, in the western Arabian Peninsula .........................................................................................................................................................104 Abstract ........................................................................................................................................104 Introduction ..................................................................................................................................105 Results ..........................................................................................................................................111 Conclusion ....................................................................................................................................116 References ....................................................................................................................................117 Table .............................................................................................................................................119 Figures ..........................................................................................................................................120 Statement of Authorship ..................................................................................................................................123 Chapter 5: Effects of the mistletoe Plicosepalus curviflorus on the water status and photosynthetic performance of four host species in the western Arabian Peninsula .............................................................124 Summary ......................................................................................................................................125 Introduction ..................................................................................................................................126 Materials and Methods ..................................................................................................................128 Results ..........................................................................................................................................131 Discussion.....................................................................................................................................136 References ....................................................................................................................................140 Tables ...........................................................................................................................................143 Figures ..........................................................................................................................................148 Appendix ......................................................................................................................................154 Statement of Authorship ..................................................................................................................................155 Chapter 6: Heavy mistletoe infection increases water and light stress in Vachellia gerrardii in dryland regions of the western Arabian Peninsula ......................................................................................................156 Summary ......................................................................................................................................156 Introduction ..................................................................................................................................158 Results ..........................................................................................................................................163