4.4

• Scientists believe that all living things on Earth share common ancestors
• It is the goal of scientists to determine how all organisms connect to each other in the evolutionary tree of life
• Infer evolutionary relationships among organisms


  Using the evidence of evolution
• Taxonomy


  The process of organizing organisms based on taxonomic hierarchy
• Systematics


  The study of the diversity of organisms and how related these organisms are
• Taxonomic Hierarchy


  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Organisms that are more closely related, share much more in common with their taxonomic hierarchy compared to a more distantly-related organism
• Taxonomy


  Involves naming and classifying organisms based on characteristics and relatedness
• There are many birds called "eagles" but they still have different taxonomic classifications
• Scientific Names


  The use of scientific names as a standard in the scientific community allows easier access for studying the same organism and prevents confusion between different studies
• Scientific Name


  Composed of two components: the genus name and the specific epithet
• Systematics as an interdisciplinary study
• Evidence and Tools for Studying Evolution

  • Structural Evidence
  • Molecular Evidence
  • Tools for Studying Evolution
• Structural Evidence


  Scientists primarily focus on certain morphological and anatomical characteristics that may indicate common descent
• All chordates share 5 crucial features as an example of structural evidence for descent
• Molecular Evidence


  Involves studying molecules like DNA, RNA, and proteins to deduce how species are related to each other
• DNA sequencing can reveal evolutionary relationships
• Cladograms


  A diagram that shows relationships between organisms based on characteristics
• The length of the branches in a cladogram merely indicate ancestry and descent
• Parts of a Cladogram

  • Terminal Nodes
  • Branches
  • Root
• Sample Cladogram


  • 4 Terminal Nodes
• Phylogenetic Trees


  May be based on physical characteristics but more commonly use genetic data to show the relationships between organisms
• Unlike cladograms, the branch length of some phylogenetic trees may be an indicator of when the divergence occurred
• Parts of a Phylogenetic Tree

  • Terminal Nodes
  • Branches
  • Root
  • Internal Nodes
• Cladograms show relationships between organisms based purely on characteristics
• Taxonomy involves the naming of organisms
• The specific epithet is the second name in the scientific name
• Scientific names should follow the format of genus name and specific epithet when handwritten
• In diagrams that show relationships between organisms, terminal nodes refer to the groups or species that are distantly related and are added for comparison
• Taxonomic Hierarchy


  The process of organizing organisms into multiple levels of organization
• Systematics


  Focuses on the diversity of organisms and how related these organisms are
• Structural Evidence


  Scientists focus on morphological and anatomical characteristics that indicate common descent
• Molecular Evidence


  Involves studying molecules like DNA, RNA, and proteins to deduce how species are related
• Taxonomy and systematics often go hand-in-hand because they both focus on understanding the relationships between organisms