TAXONOMY AND CLASSIFICATION

• Why Classify?


  Better understand organisms so it can be organized properly
• Classification


  Grouping of objects/organisms based on similarities/common ancestors and characteristics
• Taxonomy


  Branch of biology that groups and names organisms based of their different characteristics
• Goal of Taxonomy


  To produce formal system for naming and classifying species to illustration their evolutionary relationships
• Carolus Linnaeus


  Swedish naturalist that devised a two-part naming system known as binomial nomenclature and developed the hierarchical system which classifies in levels based on physical similarities.
• How many organisms did Carlos Linnaeus described?


  6,000 animals and 4,000 plants using Latin words
• Binomal Nomenclature

  1. Standard two-part system for naming things
  2. The first word identifies the genus of organisms
  3. Genus (genera in plural) consist of a group of similar species
  4. The second word (which sometimes describes a characteristic of the organisms) is called the specific epithet
• Latin is used in writing scientific names because it is no longer used un conversation and therefore does not change.
• Scientific names should be italicized in print and underlined when handwritten.
• First letter in genus is uppercase while the specific epithet is lowercase.
• How is scientific name assigned?

  • Where it was first discovered
  • Who discovered it
• Modern Classification


  Grouping organisms based on their evolutionary relationships makes it easier to understand biological diversity.
• Taxon (taxa in plural)


  A group of organisms
• Organisms are ranked in taxa that range from havung very broad characteristics to very specific ones.
• Taxonomic Hierarchy

  1. Kingdom
  2. Phylum
  3. Class
  4. Order
  5. Family
  6. Genus
  7. Specific epithet (species)
• Importance of Taxonomic Hierarchy

  • Place organisms in logical hierarchy
  • Place organisms into categories that show ancestor-descendant relationships
• Scientists organize over 2 million organisms.
• Aristotle classified organisms as either plants (plantae) or animals (animalia).
• Which level is more specific than genus?


  Species
• What is the next level that is more genral than family?

  Order
• Which levels are more specific than order?

  Family, Genus, Species
• Which is the most general level?

  Kingdom
• Criteria to classify organisms

  1. Structural similarities: similar fossils or similarities
  2. Biochemical analysis: DNA, proteins, and amino acids
  3. Embryology: similar embryos
• Phylogeny


  Studt of the evolutionary relationships among a group of organisms
• Phylogenic Tree

  • Represents a branching "tree-like" structure which illustrates the evolutionary relationships of a group of organisms
  • Shows when in time traits developed
• How to read a phylogenetic tree?

  • Step 1: See the root as ancestor and tips as descendants (group of species)
  • Step 2: See the daughter lineages (splits up into two or more branches creating a line of distinction between to or more species)
  • Step 3: See the shared ancestry between lineages
  • Step 4: Read the diagram as a whole

  
• Primitive = old, simple

  • The most primitive species are at the bottom (left)
  • The most recent species are at the top (right)
• Cladistics

  • Classification based on common ancestry
  • It is a common method to make evolutionary trees called cladograms
  • Classification based on derived traits
  • Species placed in order that they descended from common ancestor