Evolution and Diversity of Cuticular Hydrocarbon Profiles of Cuckoo Wasps
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Evolution and diversity of cuticular hydrocarbon profiles of cuckoo wasps Doctoral thesis for a doctoral degree at the Faculty of Biology, University of Würzburg submitted by Ruth Castillo Cajas from Lima, Perú Würzburg, 2018 Submitted on: ....................... Members of the Promotionskommission: Chairperson Prof. Dr. Supervisors Prof. Dr. Thomas Schmitt Prof. Dr. Oliver Niehuis Date of the public defense: ....................... Date of receipt of certificates: ....................... Believe you can and you are halfway there. (T. Roosevelt) Eidesstattliche Erklärungen nach §4 Abs. 3 Satz 3, 5, 8 der Promotionsordnung der Fakultät für Biologie Affidavit I hereby declare that my thesis entitled: „Evolution and diversity of cuticular hydrocarbon profiles of cuckoo wasps” is the result of my own work. I did not receive any help or support from commercial consultants. All sources and / or materials applied are listed and specified in the thesis. Furthermore I verify that the thesis has not been submitted as part of another exam- ination process neither in identical nor in similar form. Eidesstattliche Erklärung Hiermit erkläre ich an Eides statt, die Dissertation: „Evolution and diversity of cuticular hydrocarbon profiles of cuckoo wasps“, eigenständig, d. h. insbesondere selbständig und ohne Hilfe eines kommerziellen Promotionsberaters, angefertigt und keine anderen, als die von mir angegebenen Quellen und Hilfsmittel verwendet zu haben. Ich erkläre außerdem, dass die Dissertation weder in gleicher noch in ähnlicher Form bereits in einem anderen Prüfungsverfahren vorgelegen hat. Würzburg, den...................... ........................................ Signature PhD-student Contents Summary 1 Zusammenfassung 5 1. Introduction 9 1.1. Cuticular hydrocarbons . 9 1.1.1. Diversity and evolution of CHC . 11 1.2. Coevolution, cuckoo wasps and chemical mimicry . 12 1.3. Phylogenetic Comparative Methods (PCM) . 13 1.4. Aims of this thesis . 13 1.5. Outline . 14 2. The family Chrysididae and their hosts: The study group 17 2.1. Diversity and distribution . 17 2.2. Morphology . 17 2.3. Classification and systematics . 19 2.4. Biology and behavior . 20 2.5. Ecology and their hosts . 23 2.6. Cuckoo wasps as model organisms to study the evolution of CHC . 24 3. Phylogeny and host associations of cuckoo wasps 25 3.1. Abstract . 25 3.2. Introduction . 25 3.3. Material and Methods . 28 3.3.1. Taxon sampling . 28 3.3.2. DNA extraction for sequencing . 28 3.3.3. Assembly of DNA sequences . 29 3.3.4. Phylogenetic Analysis . 29 3.3.5. Compilation of host usage information . 30 3.4. Results and Discussion . 31 3.4.1. Dataset and tree inference statistics . 31 3.4.2. Phylogenetic results and their implications for the current genus- level classification of cuckoo wasps subfamilies and tribes . 32 3.4.3. Elampini . 35 3.4.4. Parnopini . 36 3.4.5. Chrysidini . 36 3.4.6. Host associations . 39 3.4.7. Conclusion . 41 3.5. Acknowledgements . 41 i Contents Contents 4. Sexual dimorphism of cuticular hydrocarbons in Chrysididae 43 4.1. Abstract . 43 4.2. Introduction . 43 4.3. Material and Methods . 45 4.3.1. Collection of samples . 45 4.3.2. GC/MS analysis . 46 4.3.3. Characterization of cuticular hydrocarbons . 46 4.3.4. Selection of samples and CHC for the analyses . 47 4.3.5. General comparisons and patterns . 47 4.3.6. Calculation of sexual dimorphism . 48 4.3.7. Identification of sex-specific differences . 48 4.4. Results . 49 4.4.1. Cuticular hydrocarbon profiles of female and male cuckoo wasps 49 4.4.2. Patterns of CHC profile variation among species . 50 4.4.3. Sexual dimorphism of CHC profiles . 54 4.4.4. Sex-specificity and sex differences . 58 4.5. Discussion . 58 4.5.1. Chemical diversity and complexity of CHC compounds . 58 4.5.2. Sexual dimorphism of CHC profiles . 62 4.5.3. Sex specific signaling . 65 4.5.4. Conclusions . 66 5. Species-specific patterns of CHC in cuckoo wasps 69 5.1. Abstract . 69 5.2. Introduction . 69 5.3. Material and Methods . 72 5.3.1. Collection of samples . 72 5.3.2. GC/MS analysis . 73 5.3.3. Characterization of cuticular hydrocarbons . 73 5.3.4. Statistical analysis . 74 5.4. Results . 77 5.4.1. Species specificity and intraspecific variability . 77 5.4.2. Stability of CHC across geographic regions . 78 5.4.3. Indicator Compound analysis . 81 5.4.4. Estimating phylogenetic relationships from CHC profiles . 84 5.5. Discussion . 87 5.5.1. Species specific signaling and the use of CHC in chemotaxonomy 87 5.5.2. Stability of CHC across geographic regions . 91 5.5.3. Intraspecific variation of CHC profiles . 92 5.5.4. Use of CHC in chemosystematics . 93 6. Natural selection and sexual dimorphism of CHC 95 6.1. Abstract . 95 6.2. Introduction . 95 6.3. Materials and Methods . 98 6.3.1. Collection of wasps . 98 6.3.2. Gas Chromatography/Mass Spectrometry . 98 6.3.3. Chemical characterization of CHC profiles . 98 ii Contents 6.3.4. Calculation of chemical dimorphism . 99 6.3.5. Molecular phylogeny of Chrysididae . 100 6.3.6. Calculation of phylogenetic signal . 100 6.3.7. Tempo and mode of CHC evolution . 101 6.4. Results . 102 6.4.1. General patterns of CHCs in females and males of Chrysididae . 102 6.4.2. Chemical dimorphism . 103 6.4.3. Phylogenetic signal . 103 6.4.4. Tempo and mode of evolution . 105 6.5. Discussion . 111 6.5.1. Stronger phylogenetic signal in males than in females . 112 6.5.2. Differences among compound classes . 114 6.6. Conclusion . 117 7. Evidence for chemical coevolution between Hedychrum and their hosts 119 7.1. Abstract . 119 7.2. Introduction . 119 7.3. Methods . 122 7.3.1. Collection and origin of the insect samples . 122 7.3.2. Molecular procedures and phylogenetic analyses . 122 7.3.3. Chemical Analyses . 123 7.3.4. Statistical analysis . 125 7.4. Results . 125 7.4.1. Molecular phylogeny and evolutionary relationships . 125 7.4.2. Cuticular hydrocarbon composition . 125 7.4.3. Changes in the chain length of COLw . 127 7.4.4. Characterization of the chemical space . 127 7.4.5. Host-parasite chemical distances . 131 7.4.6. Intra and interspecific variability of HYMw and COLw hosts . 131 7.5. Discussion . 133 7.5.1. CHC diversification in COLw reduces the chemical overlap be- tween COLw and their brood parasites potentially facilitating parasite escape . 135 7.5.2. CHC profile diversification is stronger in female COLw hosts than in their conspecific males . 138 7.5.3. CHC profiles of female cuckoo wasps, but not those of male cuckoo wasps, are similar to those of their hosts (only in COLw) 138 7.6. Conclusions . 139 8. A proposed pipeline for the analysis of cuticular hydrocarbons 141 8.1. Abstract . 141 8.2. Analysis of cuticular hydrocarbons . 141 8.3. Description of the proposed pipeline . 145 8.3.1. Creating a mass spectral library . 145 8.3.2. Running the batch files . 148 8.3.3. Parameters setting . 150 8.3.4. Correcting the result files of AMDIS . 150 8.3.5. Post-processing the data . 152 iii Contents Contents 8.3.6. Graphical visualization of the corrected data . 153 8.4. Discussion and concluding remarks . 154 9. A useful tool for the quick identification of methyl-branched hydrocarbons157 9.1. Abstract . 157 9.2. Introduction . 157 9.3. Methods . 162 9.3.1. Implementation of diagnostic ions of methyl-branched hydro- carbons . ..