Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1506 Morphometric analysis of Cambrian fossils and its evolutionary significance ILLIAM JACKSON ACTA UNIVERSITATIS UPSALIENSIS ISSN 1651-6214 ISBN 978-91-554-9894-8 UPPSALA urn:nbn:se:uu:diva-319487 2017 Dissertation presented at Uppsala University to be publicly examined in Norrlands 1 & 2, Villavägen 16, Uppsala, Friday, 2 June 2017 at 13:00 for the degree of Doctor of Philosophy. The examination will be conducted in English. Faculty examiner: Professor Nigel Hughes (University of California, Riverside). Abstract Jackson, I. 2017. Morphometric analysis of Cambrian fossils and its evolutionary significance. Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 1506. 63 pp. Uppsala: Acta Universitatis Upsaliensis. ISBN 978-91-554-9894-8. The Extended Evolutionary Synthesis (EES) is currently emerging as a theoretical alternative to the Modern Synthesis (MS) in which to frame evolutionary observations and interpretations. These alternative frameworks differ fundamentally in their understanding of the relative roles of the genotype, phenotype, development and environment in evolutionary processes and patterns. While the MS represents a gene-centred view of evolution, the EES instead emphasizes the interactions between organism, development and environment. This novel theoretical framework has generated a number of evolutionary predictions that are mutually incompatible with the equivalent of the MS. While research and empirical testing has begun on a number of these in a neontological context, the field of palaeontology has yet to contribute meaningfully to this endeavour. One of the reasons for this is a lack of methodological approaches capable of investigating relevant evolutionary patterns in the fossil record. In this thesis morphometric methods capable of providing relevant data are developed and employed in the analysis of Cambrian fossils. Results of these analyses provide empirical support for the process of evolution through phenotypic plasticity and genetic assimilation hypothesized by the EES. Furthermore, theoretical revision to the species concept in a palaeontological context is suggested. Finally, predictions of the EES specific to the fossil record are made explicit and promising directions of future research are outlined. Keywords: Extended Evolutionary Synthesis, phenotypic plasticity, genetic assimilation, phenotypic accommodation, Agnostus pisiformis, Mackinnonia, elliptical fourier analysis, species concept Illiam Jackson, Department of Earth Sciences, Palaeobiology, Villav. 16, Uppsala University, SE-75236 Uppsala, Sweden. © Illiam Jackson 2017 ISSN 1651-6214 ISBN 978-91-554-9894-8 urn:nbn:se:uu:diva-319487 (http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-319487) For Steph List of Papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals: I Jackson, I. S. C. & Budd, G. E. (2017) Intraspecific morpholog- ical variation of Agnostus pisiformis, a Cambrian Series 3 trilo- bite-like arthropod. Lethaia, published online 15 March 2017. doi:10.1111/let.12201 II Jackson, I. S. C. & Claybourn, T. M. (manuscript submitted to Palaeontology) Morphometric Analysis of the Early Cambrian mollusc Mackinnonia and the Incipient Species Concept. III Jackson, I. S. C., Bohlin, M. S., Mann, R. P., Budd, G. E. (man- uscript submitted to Nature) Genetic assimilation in the fossil record: phenotypic plasticity and accommodation in Cambrian arthropods. IV Jackson, I. S. C. & Budd, G. E. (manuscript) The Extended Evo- lutionary Synthesis in the fossil record. Additionally, the following paper was prepared during the course of the PhD, but is not included in the thesis: I Budd, G. E. & Jackson, I. S. C. (2016) Ecological innovations in the Cambrian and the origins of the crown group phyla. Philo- sophical Transactions of the Royal Society B 371, 20150287. doi:10.1098/rstb.2015.0287 Reprints were made with permission from the respective publishers. Statement of authorship Paper I: I. J. collected the material and conducted the analyses, and interpreted the results and authored the paper with input from G. B. Paper II: I. J. analysed the material, and interpreted the results and co-authored the paper together with T. C. Paper III: I. J. collected material and conducted the morphometric analyses, and co-authored the bulk of the paper together with G. B. Paper IV: I. J. authored the paper with input from G. B. Contents Introduction ..................................................................................................... 9 Organismal variation is continuous .............................................................. 11 A brief history of classification ................................................................ 11 Phylogenetics ........................................................................................... 12 Morphometrics and stratophenetics .......................................................... 17 Morphometric methods ............................................................................ 22 Summary .................................................................................................. 23 Case study ................................................................................................ 23 The morphological variation of Mackinnonia .............................................. 24 Helcionelloida .......................................................................................... 24 Mackinnonia ............................................................................................. 24 Morphological variation and the incipient species concept ..................... 25 Natural selection acts on the phenotype ........................................................ 28 The level of selection ............................................................................... 28 The Extended Evolutionary Synthesis ..................................................... 29 Evolution through phenotypic plasticity and genetic assimilation ........... 31 Macroevolutionary patterns ...................................................................... 33 Quantum evolution ................................................................................... 35 Summary .................................................................................................. 39 Case study ................................................................................................ 40 The phenotypic plasticity of Agnostus pisiformis ......................................... 41 Agnostus pisiformis .................................................................................. 41 Intraspecific variation ............................................................................... 42 Patterns of phenotypic plasticity and genetic assimilation ....................... 43 Conclusion .................................................................................................... 47 Organismal variation is continuous .......................................................... 47 Natural selection acts on the phenotype ................................................... 47 Future directions ........................................................................................... 49 Morphometrics in the fossil record .......................................................... 49 Cambrian explosion .................................................................................. 49 Svensk Sammanfattning ................................................................................ 51 Introduktion .............................................................................................. 51 Evolution genom fenotypisk plasticitet och genetisk assimilation ........... 52 Variation som ett kontinuerligt spektrum ................................................. 52 Morfologisk variation hos Mackinnonia .................................................. 53 Fenotypisk plasticitet och genetisk assimilation hos Agnostus pisiformis .................................................................................................. 53 Slutsatser och framtidsutsikter ................................................................. 54 Acknowledgements ....................................................................................... 55 References ..................................................................................................... 57 Introduction Scientific research takes place within a theoretical framework, which can be defined as a set of implicit or explicit assumptions, conceptualizations and perspectives. This framework determines both the research questions that can be explored and the methods that can be developed. These are interdependent; novel perspectives permit the development of new methodologies and new methodologies make possible the investigation of novel research questions. It is essential, therefore, from time to time to critically review the framework in which a field of research is being conducted and to evaluate how this frame- work is affecting the scope and potential of the research within that field. The Extended Evolutionary Synthesis (EES; Laland et al., 2015) is one such currently emerging reevaluation of a theoretical framework. Specifically it seeks to revise or extend the Modern Synthesis (MS) in evolutionary biol- ogy. Although this sounds dramatic,