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Lake Tanganyika Reflected by Radular Tooth Morphologies and Material Properties

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Lake Tanganyika Reflected by Radular Tooth Morphologies and Material Properties Trophic specialization of paludomid gastropods from ‘ancient’ Lake Tanganyika reflected by radular tooth morphologies and material properties Dissertation zur Erlangung des Doktorgrades an der Fakultät für Mathematik, Informatik und Naturwissenschaften Fachbereich Biologie der Universität Hamburg vorgelegt von Wencke Krings Hamburg, 2020 Vorsitzender der Prüfungskommission: Prof. Dr. Jörg Ganzhorn Erst- und Zweitgutachter: Prof. Dr. Susanne Dobler, Prof. Dr. Stanislav Gorb Datum der Disputation: 06.11.2020 2 Table of contents Table of contents .............................................................................................................................................. 3 Chapter 1. Introduction .................................................................................................................................... 7 Molluscan diversity and evolution ............................................................................................................ 7 Ecological niches and trophic specialization ............................................................................................. 7 The radula as a Molluscan key innovation and mechanical interface ....................................................... 8 Hypotheses integrating tooth structure, mechanical properties, ecology, and evolution: model system Paludomidae from Lake Tanganyika........................................................................................................ 12 An approach to identify the driving mechanisms in gastropod evolution resulting in species diversity based on the radula ................................................................................................................................. 17 Objectives and hypotheses:..................................................................................................................... 19 References ............................................................................................................................................... 20 Chapter 2. Functional morphology of paludomid radular teeth ................................................................... 29 2. 1 Filling the lake: tracing convergent trophic specialization in the evolution of paludomid gastropods in Lake Tanganyika .......................................................................................................................................... 29 Abstract ................................................................................................................................................... 29 Introduction ............................................................................................................................................. 30 Materials and Methods ........................................................................................................................... 33 Results ..................................................................................................................................................... 36 Discussion and Conclusion....................................................................................................................... 40 References ............................................................................................................................................... 44 Supplementary Material .......................................................................................................................... 50 2. 2 Tightening it up: Diversity of the Chitin Anchorage of Radular-Teeth in paludomid Freshwater- Gastropods .................................................................................................................................................. 55 Abstract ................................................................................................................................................... 55 Introduction ............................................................................................................................................. 56 Material and Methods ............................................................................................................................. 60 Results ..................................................................................................................................................... 68 Discussion ................................................................................................................................................ 72 References ............................................................................................................................................... 75 Supplementary Material .......................................................................................................................... 79 3 Chapter 3. Functional morphology and material properties of Spekia zonata – a case study .................... 83 3. 1 Differences in the Young modulus and hardness reflect different functions of teeth within the taenioglossan radula of gastropods ............................................................................................................ 83 Abstract ................................................................................................................................................... 83 Introduction ............................................................................................................................................. 85 Materials & Methods ............................................................................................................................... 88 Results ..................................................................................................................................................... 93 Discussion ................................................................................................................................................ 95 References ............................................................................................................................................. 100 3. 2 Finite element analysis of individual taenioglossan radular teeth (Mollusca) ................................... 105 Abstract ................................................................................................................................................. 105 Introduction ........................................................................................................................................... 107 Materials and Methods ......................................................................................................................... 113 Results ................................................................................................................................................... 120 Discussion .............................................................................................................................................. 128 References ............................................................................................................................................. 135 Supplements .......................................................................................................................................... 143 Chapter 4. Trophic specialization ................................................................................................................. 147 4. 1 Trophic specialisation reflected by radular tooth material properties in an ‘ancient‘ Lake Tanganyikan gastropod species flock ............................................................................................................................. 147 Abstract ................................................................................................................................................. 147 Background ............................................................................................................................................ 149 Results ................................................................................................................................................... 154 Discussion .............................................................................................................................................. 168 Methods ................................................................................................................................................ 174 Declarations ........................................................................................................................................... 177 Literature ............................................................................................................................................... 178 Supplementary ...................................................................................................................................... 186 Chapter 5. Summary and Discussion ............................................................................................................ 191 Morphology, mechanical properties, and ecology .................................................................................... 191 The role of morphology (Objectives 1, 2, 4, 5; chapter 2.1, 2.2, 3.2) .................................................... 191 The role of mechanical properties (functional gradients) in combination with morphology (Objectives
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