Dissertation submitted to the Combined Faculties for the Natural Sciences and for Mathematics of the Ruperto-Carola University of Heidelberg, Germany for the degree of Doctor of Natural Sciences presented by Diplombiologin Mascha Bischoff born in Aachen Date of oral examination: Pollination ecology of the New Zealand alpine flora Referees: Prof. Dr. Claudia Erbar Prof. Dr. Peter Leins Your head is humming, and it won’t go, in case you don’t know. The piper’s calling you to join him. (Led Zeppelin 1971) All data in the presented thesis was collected by myself. The plant phenology data was collected with Ms. Lisa R. Dobbie. The modelling in bee colour space was carried out in collaboration with Dr. Adrian Dyer, Monash University, Australia. The identification of floral scent compounds was done under supervisison of Dr. Andreas Jürgens, University of KwaZulu-Natal, South Africa. Photographs were taken by myself, Frank Wellenreuther and Dr. Alastair W. Robertson. Table of contents 1 Summary........................................................................................................................... 1 1.1 English summary.................................................................................................................................. 3 1.2 Deutsche Zusammenfassung ................................................................................................................ 4 2 Introduction ...................................................................................................................... 7 2.1 The principles of pollination ecology – then and now ......................................................................... 9 2.2 Pollination in the New Zealand flora – what do we know? ............................................................... 13 2.3 Do plants in alpine New Zealand depend on pollinator service at all? ............................................. 15 2.4 Are alpine pollination networks in New Zealand entirely generalised? ............................................ 17 2.5 Which floral traits maintain interaction patterns between flowers and insect visitors?.................... 19 3 Materials and methods................................................................................................... 21 3.1 Study area .......................................................................................................................................... 23 3.2 Study plants........................................................................................................................................ 25 3.3 Laboratory equipment........................................................................................................................ 27 3.4 Assessing the reproductive system ..................................................................................................... 27 3.4.1 Pollen/ovule ratios......................................................................................................................... 27 3.4.2 Pollen on stigma/ovule ratios under natural and experimental conditions .................................... 28 3.4.3 Fruit and seed set under natural and experimental conditions....................................................... 29 3.5 Analysing the plant-pollinator network.............................................................................................. 32 3.5.1 Plant phenology............................................................................................................................. 32 3.5.2 Insect phenology ........................................................................................................................... 32 3.5.3 Visitor observations....................................................................................................................... 33 3.5.4 Pollen library................................................................................................................................. 34 3.5.5 Pollen loads on insect bodies......................................................................................................... 35 3.5.6 Pollen loads on receptive stigmas.................................................................................................. 35 3.5.7 Analysis of pollination network parameters.................................................................................. 36 3.6 The floral attractants ......................................................................................................................... 37 3.6.1 Flower colour analysis .................................................................................................................. 37 3.6.2 Floral scent analysis ...................................................................................................................... 39 3.7 Data Analysis..................................................................................................................................... 41 4 Results ............................................................................................................................. 43 4.1 Summary of all experimental work..................................................................................................... 45 4.2 Reproductive system........................................................................................................................... 46 4.2.1 Pollen/ovule ratios......................................................................................................................... 46 4.2.2 Pollen on stigma/ovule ratios under natural and experimental conditions .................................... 48 4.2.3 Fruit and seed set under natural and experimental conditions....................................................... 52 4.2.4 Summary of the reproductive system results................................................................................. 55 4.3 Plant-pollinator network.................................................................................................................... 57 4.3.1 Plant phenology............................................................................................................................. 57 4.3.2 Insect phenology ........................................................................................................................... 58 4.3.3 Visitor observations....................................................................................................................... 59 4.3.4 Pollen loads on insect bodies......................................................................................................... 61 4.3.5 Pollen loads on receptive stigmas.................................................................................................. 65 4.3.6 Comparing the emerging networks ............................................................................................... 68 4.4 Floral attractants ............................................................................................................................... 72 4.4.1 Flower colour ................................................................................................................................ 72 4.4.2 Floral scent.................................................................................................................................... 74 5 Discussion........................................................................................................................ 89 5.1 Do plants in alpine New Zealand depend on pollinator service at all? ............................................. 91 5.2 Are alpine pollination networks in New Zealand entirely generalised? ............................................ 95 5.3 Which floral traits maintain interaction patterns between flowers and insect visitors?.................. 100 5.4 General conclusions and future research ........................................................................................ 106 6 References ..................................................................................................................... 107 7 Appendix ....................................................................................................................... 119 7.1 Details of plant species under investigation ....................................................................................121 7.2 Phenology of plant species under investigation............................................................................... 132 7.3 Spectral reflectance curves of plant species under investigation..................................................... 138 7.4 Insect visitor groups......................................................................................................................... 146 8 Acknowledgements....................................................................................................... 151 Index of figures Fig. 2.1 Plant animal mutualistic interaction matrices (Bascompte et al. 2003, modified)................................... 18 Fig. 3.1 The experimental site (a) in July during the ski season and (b) in February during the field season....... 24 Fig. 3.2 Map of the experimental area in the Remarkables ski field area. ............................................................ 25 Fig. 3.3 Pollinator exclusion experiments on Viola cunninghamii (Violaceae). ................................................. 30