General Biology 4A

• Regardless of similarities or differences, all organisms are related evolutionarily
• Explain how the structural and developmental characteristics and relatedness of DNA sequences are used in classifying living things

  1. Structural characteristics

  2. Developmental characteristics

  3. DNA sequence relatedness
• Taxonomy is the science of describing, identifying, naming, and classifying organisms
• Taxonomy takes into account how organisms are related, but it does not totally reflect evolutionary relationships
• Taxonomic traits


  Characters used to classify organisms according to their taxonomic groups
• Ancestral traits


  Evolutionary traits that are homologous within groups of organisms
• Derived traits


  Characters that are present in a species but absent from their ancestor
• Taxonomic evidence for identifying relatedness among individuals

  • Morphological traits
  • Developmental traits
  • Physiological traits
  • Genetic traits
• Morphological traits


  Set of physical features of living organisms, including external and internal features
• Developmental traits


  Set of developmental features that can be used for classification
• Physiological traits


  Functional features of structures
• Genetic traits


  Specific sequences of DNA in organisms
• Genetic and morphological data must go parallel when constructing a taxonomic tree
• Taxonomic hierarchy is usually being used to classify organisms
• Homologous structures are those that vary in form but share a highly similar function
• The development of organisms is relevant in understanding the evolutionary path of most taxa
• Pharyngeal slits in vertebrates are developmental traits
• Homology in forearms of vertebrates are morphological traits
• Analogy in the wings of birds and insects are physiological traits