The Phylogeny and Evolutionary Biology of the Pimplinae (Hymenoptera : Ichneumonidae)
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THE PHYLOGENY AND EVOLUTIONARY BIOLOGY OF THE PIMPLINAE (HYMENOPTERA : ICHNEUMONIDAE) Paul Eggleton A thesis submitted for the degree of Doctor of Philosophy of the University of London Department of Entomology Department of Pure & Applied B ritish Museum (Natural H istory) Biology, Imperial College London London May 1989 ABSTRACT £ The phylogeny and evolutionary biology of the Pimplinae are investigated using a cladistic compatibility method. Cladistic methodology is reviewed in the introduction, and the advantages of using a compatibility method explained. Unweighted and weighted compatibility techniques are outlined. The presently accepted classification of the Pimplinae is investigated by reference to the diagnostic characters used by earlier workers. The Pimplinae do not form a natural grouping using this character set. An additional 22 new characters are added to the data set for a further analysis. The results show that the Pimplinae (sensu lato) form four separate and unconnected lineages. It is recommended that the lineages each be given subfamily status. Other taxonomic changes at tribal level are suggested. The host and host microhabitat relations of the Pimplinae (sensu s tr ic to ) are placed within the evolutionary framework of the analyses of morphological characters. The importance of a primitive association with hosts in decaying wood is stressed, and the various evolutionary pathways away from this microhabitat discussed. The biology of the Rhyssinae is reviewed, especially with respect to mating behaviour and male reproductive strategies. The Rhyssinae (78 species) are analysed cladistically using 62 characters, but excluding characters thought to be connected with mating behaviour. Morphometric studies show that certain male gastral characters are associated with particular mating systems. These characters are used in a reanalysis of the data set, and indicate that one genus (Megarhyssa) appears to have evolved an extreme scramble competition system uniquely. The reanalysed results are used to recommend changes in the generic limits within the Rhyssinae.- Explanations for the evolution of rhyssine mating systems are evaluated. The evolutionary biology and biogeography of the group is discussed. 2 ACKNOWLEDGEMENTS I would like to thank the following people who have provided me with material, advice or data. M. Fitton, my museum supervisor, and J. Waage, my University supervisor. I. Gauld for imparting some of his extensive knowledge of ichneumonids and other parasitoids to me, and for acting as a 'third supervisor’ throughout. P. Williams and N. Fergusson for the hours of their time spent discussing the ideas and techniques used in this thesis. S. Wiseman for proof reading much of the manuscript. G. Thompson for letting me use his data and photographs from his alder-woodwasp work, and for his helpful comments. The Danum Valley Management committee and the Royal Society for permission to work at the Danum Valley Field Centre, Sabah, East Malaysia. I would also like to thank the following for their advice or assistance during the project: M. Day, N. Springate, R. Belshaw, G. Underwood, M. S till, T. Huddleston, D. Wahl, P. Hammond, C. Lyal, N. Stork, E. Bean, R. Spradbery, C. O'Toole, R. van Achterberg, C. Malumphy and the 1985 Imperial College student expedition to Sabah, G. Ellison, M. Shaw, the librarians at the BM(NH) , the EM and photographic unit of the BM(NH). This study was made possible by the award of a research fellowship by the trustees of the British Museum (Natural History), which is gratefully acknowledged. I would also like to thank Dr L.A. Mound, keeper of Entomology, for the use of the collections and facilities. 3 CONTENTS Page A bstract 2 Acknowledgments 3 Contents 4 List of figures 9 L ist of tab les 15 1 Introduction and methods 19 1.1 Introduction 19 1.2 Choice of methods of phylogenetic reconstruction 21 1.2.1 Phenetics (numerical taxonomy) 22 1.2.2 Evolutionary taxonomy 22 1.2.3 Cladistics 22 1.2.4 What can cladistics tell us? 23 1.2.5 Methodology of cladistics - parsimony or com patibility 24 1.2.6 Which method is suitable here? 29 1.3 Definitions and assumptions 32 1.4 Techniques of compatibility analysis 33 1.4.1 LEQU/PROB$ analyses 33 1.4.2 O'NOMOD analyses 36 1.4.3 Reintroducing incompatible characters 39 1.5 Sources of homoplasy 40 1.6 Cladograms, trees and scenarios 41 2 The Pimplinae: the present classification 44 2.1 Introduction 44 2.2 Historical review 44 2.3 The Townes classification 46 2.4 Testing the Townes classification 48 2.4.1 Outgroups 48 a. The holophyly of the Pimplinae 48 The character states 50 R esults 55 Cladograms: initial output 55 Trees: phylogenetic hypotheses 58 The phylogeny of the Pimplinae 63 Introduction 63 Head 63 Back of the head 63 Mouthparts 65 Antennal structure 65 Thorax 71 Introduction 71 The prothorax 71 The mesothorax 77 Thoracic musculature 82 Wings 83 Legs 83 Abdomen 85 Propodeal carination 85 Attachment of gaster to propodeum 85 Gastral tergites 85 Ovipositor complex 86 T ergite 9 86 O vipositor 88 Gonostylus 9 (ovipositor sheath) 88 Larval structures 90 R esults 91 Cladograms: initial analyses 91 Trees: phylogenetic hypotheses 93 Subset analyses 94 The holophyletic groups 95 The poemeniine group 95 The Ephialtini 98 The Polysphinctini 5 u> CO The Pimplini 102 3.9 The relative positions of the groups 105 4 Evolutionary biology of the Pimplinae 110 4.1 Introduction 110 4.2 Node 1: (outgroups), the Poemeninae and Rhyssinae 119 4.2.1 M icrohabitat 1: Hard, dead wood 119 4.2.2 Microhabitat 2: aculeates in pre-existing workings 124 4.3 Node 2: The Pimplinae (sensu strie to) 125 4.4 Node 3: The E p h ia ltes-group 125 4.4.1 M icrohabitat 3: so ft wood and bark 125 4.4.2 Microhabitat 4: soft non-woody plant tissue 127 4.4.3 Microhabitat 5: exposed or lightly concealed pupae 128 4.5 Node 4: Polysphinctini and allies 129 4.5.1 Microhabitat 6: spider egg sacs 129 4.6 Node 5: the Polysphinctini 130 4.6.1 Microhabitat 7: free-living spiders 130 4.7 Node 6: the Pimplini 132 4.7.1 Microhabitat 8 : Exposed or weakly concealed Lepidoptera pupae 133 4.8 General trends 135 4.8.1 From concealed to exposed hosts 136 4.8.2 From concealed to very deeply concealed hosts 137 4.8.3 From newly fallen to rotting timber 138 4.9 Conclusions 139 5 The biology of the Rhyssinae 143 5.1 Introduction 143 5.2 Distribution 143 5.3 Sexual dimorphism 144 5.4 General adult behaviour 144 6 £ 5.4.1 Emergence timings 146 5.4.2 Meteorological effects on emergence 151 5.5 Male reproductive behaviour 152 5.5.1 Male reproductive behaviour in R hyssa and M egarhyssa 152 5.5.2 Male reproductive behaviour in R h y sse lla 158 5.5.3 Male reproductive behaviour in L ytarm es 161 5.5.4 Mating systems 165 5.5.5 Conclusions 166 5.6 Host searching and oviposition behaviour 167 5.7 Larval biology 170 6 The phylogeny of the Rhyssinae, and the evolution of their mating systems 171 6.1 Historical review 171 6.2 The present classification 171 6.3 Outgroups 172 6.4 The holophyly of the group 172 6.5 Material examined 177 6.6 Character states 178 6.7 Preliminary results 185 6.7.1 Cladograms: initial results 186 6.7.2 Trees: phylogenetic hypotheses 188 6.7.3 The LEQUB/PROBS analysis 189 6.7.4 The O'NOMOD analysis 189 6.7.5 Subset analyses 191 6.7.6 Comments on the two tre es 193 6.8 Male gasters and mating systems 195 6.8.1 Mating strategies in the Rhyssinae 198 6.8.2 Direct evidence __ 200 6.8.3 Indirect evidence 201 6.9 Is M egarhyssa a holophyletic group? 212 6.9.1 Cladograms and trees 213 6.9.2 Megarhyssaz phylogenetic conclusions 218 6.10 Phylogeny: overall conclusions 221 6.10.1 Comments on the fin a l tre e 225 7 £ 6.11 Possible explanations for the distribution of gaster shapes 230 6. 11.1 Size factors 230 6. 11.2 Intruder male numbers 230 6.11.3 Mimicry complexes 234 6.11.4 Phylogenetic constraints 235 6.12 Alternative male strategies 237 6.13 Evolutionary biology and biogeography of the Rhyssinae 240 6.13.1 Present day distribution of ] holophyletic groups 240 6.14 The evolution of the Rhyssinae : a speculative scenario 245 6.14.1 Background 245 6.14.2 R hyssa 248 6.14.3 M egarhyssa 248 6.14.4 L ytarm es 250 6.14.5 E p irh yssa 250 6.14.6 M yllen yx is 252 6.15 General conclusions 252 References 254 Appendix 1 Pimpline OTUs 281 Appendix 2 Rhyssine OTUs 282 Appendix 3 Pimpline data set 284 Appendix4 Rhyssine data set 286 Appendix 5 LEQUB initial run data 289 Appendix 6 Emergence timing data for Rhys sell a 293 Appendix 7 Gastral and forewing data 294 8 LIST OF FIGURES CHAPTER Page Fig 2.1. LEQU/PROB cladogram for the Townes data set. 56 Fig 2.2. O'NOMOD cladogram for the Townes data set. 57 Fig 2.3. Final combined hypothetical tree for the Townes data set. 61 CHAPTER Fig 3.1 Post genal region of Dolichomitus imperator showing partial fusion of postgena . 64 Fig 3.2 Notch on post-occiput of Dolichomitus im p era to r. 64 Fig 3.3 Foramen of Neoxorides collaris showing expanded lateral hollow. 66 Fig 3.4 Smooth basiconic sensillum (type A) of Liotryphon cydiae.