Download Understanding Diversity: Systematics, Themes and Patterns in Evolutionary Biology and more Slides Biology in PDF only on Docsity! Chapter 23 Understanding Diversity: Systematics Themes and Patterns over the last 4.6 billion years. Docsity.com Summary • Classifying Organisms • Tools for studying the history of life • Data • Key changes – how they occur • Adaptive radiations and mass extinctions Docsity.com Domains and Kingdoms • Domain Bacteria – P. Bacteria • Domain Archaea – P. Archaea • Eukarya – P. Protista – P. Plantae – P. Fungi – P. Animalia Docsity.com Tools for Studying the History of Life • Fossils – collection continues to grow, transitional forms are found and relationships are refined. • Phylogenies: evolutionary histories of groups (taxa) of organisms from a common ancestor. Usually depicted as trees. Note, phylogenies are testable hypotheses. Docsity.com Tools for Studying the History of Life • Criteria used – Homologies = similarities from a recent common ancestor. • ?? What charactersitics would you use?? Docsity.com Phylogenies as Trees • How are they constructed? – Systematics – 2 approaches • Phenetic – based on overall similarity among populations regardless of evolutionary relationships. • Cladistic –based on shared “derived” characteristics or synaptomorphies - characteristics derived from a common ancestor, i.e. does include evolutionary relationships. Docsity.com Phylogenies as Trees • How are they constructed? – Problems: • Characteristics that arose independently in 2 or more distantly related groups (analogous traits or homoplasy). • Loss of a derived characteristic in 1 or more closely related groups. • Lack of transitional forms. – Solution: Docsity.com Evolution and Timelines • Earth begins as a mass of hot gases and dust. • As Earth cools water is formed, evaporated and rain falls through the toxic atmosphere. • Chemical evolution – production of more complex molecules. • The first cells are formed and the journey begins. • Radiometric dating Docsity.com Cambrian Period (Paleozoic era) • Significance: rapid diversification of the species. – Multicellular organisms – Rapid increase in size and complexity of organisms. • Fossils from China (Doushantuo formation), Australia, Ukraine, Siberia, etc. (Ediacaran period), and Canada (Burgess Shale fossils) deposits are unique – soft bodied animals. Docsity.com Cambrian Period • Fossil record – How did this “explosion” of diversity happen? Docsity.com Evolution – the Process • Natural Selection – Natural selection and evolution requires genetic change. – Genetic changes: Docsity.com Genetic Mechanisms • Gene duplication – discrepancies – The number of clusters and the complexity of the organism do not always correlate, ex. zebra fish and the mouse. – ?Loss of gene clusters Docsity.com Genetic Mechanisms • Gene Expression – The time during embryogenesis when homeotic genes are expressed and the duration of their expression affects development. Docsity.com Adaptive Radiations or Star Phylogenies – chapter 20 • What are they? Docsity.com
