Evidence of Evolution

• Evidences for evolution:

  • Anatomy & Embryology
  • Molecular Biology
  • Biogeography
  • Fossil record
• Homologous features: Similar features that are inherited from a common ancestor. 


  An example: whales, birds, and humans all share extremely similar structures of forelimbs. It is theorized that such organizations were already present in a common ancestor of whales, birds, and humans.
• Vestigial structures: non-functional versions of features, ones that are almost completely useless. If these structures are homologous to useful structures, biologists can gain insights into an organism's ancestry.
• Analogous features: Structures or functions that have evolved independently but look very similar. Why? Well they might have lived in environmentally/geographically similar regions OR experienced similar selective pressures. 


  An example would be wings on bats and wings on birds. Both types of wings serve different purposes (flight) and developed separately through natural selection.
• Convergent evolution: The development of similar traits by unrelated species living under similar environmental conditions. Analogous feature is precisely this type of evolution. 


  Example: the Arctic fox and the ptarmigan are 2 distantly related species. However, they both undergo seasonal color changes because they experienced similar selective pressures (seasons).
• Homologous genes: genes that are located on the same chromosome and have similar functions. The more DNA differences between 2 species, the more distantly related the 2 are.
• Molecular Biology as an evidence of evolution:

  • Almost all living organisms share the same genetic material (DNA)
  • Almost all living organisms share the same, or VERY similar, genetic codes
  • Almost all living organisms go through the same basic process of gene expression (transcription + translation)
• Biogeography: the distribution of organisms on Earth can explain the evolutionary history of the organisms, in combination with the movement of tectonic plates over geological time.
• Fossils: Remains of organisms that have been preserved in rock.
• How do fossils connect to evolution?

  • fossils document the existence of extinct species, which show the organisms in different periods of Earth