Evolution

• Organisms


  • Have changed over time
  • Their structures, traits and abilities allowed them to adapt and survive in their environment
• Sources of evidence for evolution

  • Fossil records
  • Anatomy and morphology
  • Embryonic development
  • Biochemistry
• Fossils


  Traces of organisms that lived in the past and were preserved by natural process or catastrophic events
• Types of fossils


  • Fossils found in sedimentary rocks
  • Imprint or Impression
  • Compression
• Determining the age of fossils

  1. Paleontologists make initial estimates of the age through the position in the sedimentary rocks

  2. Relative Dating - Comparing the age of rocks

  3. Radiometric Dating - Using the decay of radioactive isotopes
• The Geologic Time Scale shows the major events in the Earth's history and the appearance of various kinds of organisms in a particular period of time on earth
• Anatomy


  The study of the parts and structure of organisms
• Morphology


  The study of structures and forms of organisms
• Homologous structures


  Structures from different species that have similar internal framework, position & embryonic development
• Analogous structures


  Structures of unrelated species that may evolve to look alike because the structure is adapted to similar function
• Divergent evolution


  • The splitting of an ancestral population into two or more subpopulations that are geographically isolated from one another
• Convergent evolution


  • An increase in similarities among species derived from different ancestors as a result of similar adaptation to similar environment
• The embryo of fishes, salamanders, lizards, birds, cats and humans are similar during the first stage of their embryonic development and have several homologous structures that are not present when the organisms are adults
• Species pairings and number of differences in amino acids

  • Human - Chimpanzee (0)
  • Human - Fruit fly (29)
  • Human - Horse (12)
  • Human - Pigeon (12)
  • Human - Rattlesnake (14)
  • Human - Red Bread Mold (48)
  • Human - Rhesus Monkey (1)
  • Human - Screwworm Fly (27)
  • Human - Snapping Turtle (15)
  • Human - Tuna Fish (21)
  • Human - Wheat (43)
  • Fruit Fly - Dogfish Shark (26)
  • Fruit Fly - Pigeon (25)
  • Fruit Fly - Screwworm (2)
  • Fruit Fly - Silkworm Moth (15)
  • Fruit Fly - Tabaco Hornworm Moth (14)
  • Fruit Fly - Wheat (47)
• Lamarck's Theory of Evolution


  Organisms change in response to their environment, and their ability to survive helped them develop characteristics necessary for them to adapt in a given environment
• Lamarck's Theory of Use and Disuse


  • Organs not in use will disappear while organs in use will develop
• Lamarck's Theory of Acquired Characteristics


  • Acquired characteristics were believed to be inherited by their offspring and propagated by the next generation
• Darwinian Theory - Theory of Natural Selection


  • Natural selection favors the survival of organisms with the best and most desirable traits, which are then passed on to the next generation
• Fitness


  • The ability of an organism to survive and produce offspring
• Variation


  • Different individuals in a population possess different characteristics and abilities, which increases the chance of survival
• Variation


  Organisms with the best and desirable traits would likely adapt to environmental changes and may gradually become better suited to survive in a given environment
• Organisms with the best adapted traits


  Will continue to reproduce and perpetuate their own kind
• Mating between surviving populations of the same species

  May shift the abundance of a new breed of organism because of mutation, gene combination and natural selection, leading to speciation