This thesis is about the complicated and multifaceted problem of the evolution of the eumetazoan body plan and its key role in the emergence of organismal complexity in the animal kingdom. As such, it draws on a very broad range of topics and discussions including empirical research programmes in palaeontology, comparative morphology, classical and genetic developmental biology, and morphological and molecular phylogenetics; as well as theoretical/philosophical research around the conceptual bases of phylogenetics, homology, scientific integration, and biological complexity and individuality. In the following chapters, I first provide background on and an outline of the thesis (chapter 1); I then propose an overarching conceptual framework for the integration of different kinds of evidence in macroevolutionary biology (chapter 2), with a special emphasis on the integration of morphological and developmental genetic evidence in inferring morphological homology (chapter 3); followed by providing a phylogeny of the major animal groups incorporating the two Ediacaran fossils Dickinsonia and Yorgia (chapter 4) and building on this phylogenetic placement to propose a novel evolutionary scenario for the evolution of key features of the eumetazoan body plan—namely the gastric cavity and bilateral symmetry—in light of Dickinsonia and other Ediacaran fossils (chapter 5). I finish with a discussion on the evolution of complexity in the animal kingdom in light of preceding chapters and the multilevel selection literature (chapter 6), and a brief final conclusion.
Evolution of the Eumetazoan Body Plan: Conceptual challenges, Ediacaran Fossils, and Organismal Complexity
Nejad Kourki, A. (Author). 2 Dec 2021
Student thesis: Doctoral Thesis › Doctor of Philosophy (PhD)