Evidence of Evolution and Phylogeny

• Fossil Record


  Gives a visual of evolutionary change over time. They can be dated by the rate of carbon 14 decay and the age of rocks where the fossils are found.
• Comparative morphology


  Analysis of the structures of living and extinct organisms
• Homology


  Characteristics in related species that have similarities even if the functions differ
• Embryonic Homology


  Many species have similar embryonic development
• Vestigial structures


  Structures that are conserved even though they no longer have a use. Like the tailbone and appendix in humans
• Molecular homology


  Many species share similar DNA and amino acid sequences
• Homologous structures


  Characteristics that are similar in two species because they share a common ancestor. Ex: bones of many species
• Convergent evolution


  Similar adaptations that have evolved in distantly related organisms due to similar environments
• Analogous structures


  Structures that are similar but have separate evolutionary origins. (not from common ancestor) Ex: wings in birds vs bats vs bees
• Biogeography

  The distribution of animals and plants geographically.
• Systematics


  Classification of organisms and determining their evolutionary relationships
• Taxonomy


  Naming and classifying species
• Phylogenetics


  The hypothesis of evolutionary history. Use phylogenetic trees to show evolution
• To determine evolutionary relationships, scientists use: Fossil records, DNA, proteins, and homologous structures
• Phylogenetic trees


  Diagrams that represent the evolutionary history of a group of organisms. Show the amount of change over time measured by fossils
• Cladograms

  Each line represents a lineage. Each branching point is a node. Nodes represent common ancestors. Nodes and all branches from it are clades. Species in a clade have shared derived features. The root is the common ancestor of all the species
• Cladograms

  Two clades that emerge from the same node are sister taxa. A lineage that evolved from the root and remains unbranched is the basal taxon.
• Cladograms

  Synapomorphy: a derived character shared by clade members.

  Derived characteristic: similarity inherited from the most recent common ancestor of an entire group.

  Ancestral characteristic: similarity that arose prior to the common ancestor
• Cladograms


  Outgroup: a lineage that is least closely related to the rest of the organisms

  Monophyletic: includes the most recent common ancestor of the group and all of its descendants

  Paraphyletic: includes the most recent common ancestor, but not all the descendants

  Polyphyletic: does not include the most recent common ancestor of all members of the group
• Parsimony


  If there are conflicts among characters, use the principle of parsimony. Use the hypothesis that requires the fewest assumptions (DNA changes)