ZENTRUM FÜR BIODIVERSITÄT UND NACHHALTIGE LANDNUTZUNG SEKTION BIODIVERSITÄT, ÖKOLOGIE UND NATURSCHUTZ − CENTRE OF BIODIVERSITY AND SUSTAINABLE LAND USE − SECTION: BIODIVERSITY, ECOLOGY AND NATURE CONSERVATION Community structure, trophic ecology and reproductive mode of oribatid mites (Oribatida, Acari) in forest ecosystems Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultäten der Georg-August-Universität Göttingen vorgelegt von Diplom-Biologin Georgia Erdmann aus Räckelwitz Göttingen, März 2012 Referent: PD Dr. Mark Maraun Koreferent: Prof. Dr. Stefan Scheu Tag der mündlichen Prüfung: 26.03.2012 Contents Summary .............................................................................................................................. 1 Reference ............................................................................................................................. 3 Chapter 1 General Introduction ...................................................................................................... 4 1. Density, diversity and distribution of oribatid mites ....................................................... 5 2. Functioning and trophic ecology of oribatid mites .......................................................... 6 3. Reproduction and life-history traits ................................................................................. 7 4. Systematics of oribatid mites ........................................................................................... 8 5. Oribatid mites as model organisms .................................................................................. 9 6. Theories about the maintenance of sexual reproduction.............................................. 10 7. Overview ........................................................................................................................ 11 References .......................................................................................................................... 14 Author Contributions ......................................................................................................... 19 Chapter 2 Stable isotopes revisited: their use and limits for oribatid mite trophic ecology .............. 20 Abstract .............................................................................................................................. 21 1. The history of the use of stable isotopes in soil food web analysis ............................... 21 2. Uncovering the trophic structure of oribatid mite communities ................................... 23 3. Recent progress .............................................................................................................. 25 4. Challenges for the future ............................................................................................... 29 5. Limitations and caveats .................................................................................................. 31 Acknowledgements……………………………………………………………………………………….……………….32 References .......................................................................................................................... 32 Appendix ............................................................................................................................ 36 Chapter 3 Regional factors rather than forest type drive the community structure of soil living oribatid mites (Acari, Oribatida) ..................................................................... 37 Abstract .............................................................................................................................. 38 1. Introduction .................................................................................................................... 38 2. Materials and Methods .................................................................................................. 40 2.1. Study sites ............................................................................................................... 40 2.2. Sampling design....................................................................................................... 40 2.3. Environmental factors ............................................................................................. 41 2.4. Statistical analysis.................................................................................................... 41 3. Results ............................................................................................................................ 42 3.1. Oribatid mite density .............................................................................................. 42 3.2. Species numbers of oribatid mites .......................................................................... 43 3.3. Community structure of oribatid mites .................................................................. 44 4. Discussion ....................................................................................................................... 47 4.1. Oribatid mite density .............................................................................................. 47 4.2. Oribatid mite diversity ............................................................................................ 48 4.3. Oribatid mite community structure ........................................................................ 49 4.2. Conclusions ............................................................................................................. 50 Acknowledgements ............................................................................................................ 50 References .......................................................................................................................... 51 Appendix ............................................................................................................................ 55 Chapter 4 Positive correlation between density and parthenogenetic reproduction in oribatid mites (Acari) supports the structured resource theory of sexual reproduction .............................. 56 Abstract .............................................................................................................................. 57 1. Introduction .................................................................................................................... 57 2. Materials and Methods .................................................................................................. 60 2.1 Regional scale ........................................................................................................... 60 2.2 Global scale .............................................................................................................. 61 2.3 Statistical Analysis .................................................................................................... 61 3. Results ............................................................................................................................ 64 3.1 Regional scale ........................................................................................................... 64 3.2 Global scale .............................................................................................................. 65 4. Discussion ....................................................................................................................... 66 4.1 Parthenogenetic reproduction in oribatid mites ..................................................... 66 4.2 Regional scale ........................................................................................................... 67 4.3 Global scale .............................................................................................................. 67 4.4 The structured resource theory of sexual reproduction as an integrative theory .. 68 Acknowledgements ............................................................................................................ 69 References .......................................................................................................................... 69 Literature used for the meta-analysis ................................................................................ 72 Appendix ............................................................................................................................ 74 Chapter 5 Oribatid mite (Acari, Oribatida) density on tree trunks is regulated by food-resources ....... 81 Abstract .............................................................................................................................. 82 1. Introduction .................................................................................................................... 82 2. Materials and Methods .................................................................................................. 84 2.1 Study sites ................................................................................................................ 84 2.2 Sampling design........................................................................................................ 85 2.3 Statistical analysis..................................................................................................... 86 3. Results ............................................................................................................................ 86 3.1 Density .....................................................................................................................