Sci Week 6

• Creationism


  The idea that all forms of life were created in their present form and remain unchanged since the beginning
• Carl von Linnaeus, the Father of Taxonomy, believed in the fixity of species
• Fossil records, developmental and molecular biology are possible evidences of evolution
• Finches


  Sparrow-like birds
• How finches ended up on the Galapagos Islands


  1. Blown out to sea by a fierce storm

  2. Lost their bearings but flew on in search of the mainland

  3. Spotted a speck of land - an island in the middle of the sea

  4. Found abundant food, shelter, nesting sites and no predators or other birds to compete with
• As the finch population grew


  Some birds were forced to fly across the sea to nearby islands
• As the plants and their seeds were just a little different on each island


  Some birds were better than others at finding and eating the new food sources
• Birds which could break open fruits and eat the seeds survived well enough to produce lots of babies
• The finches on each island were slightly different
• Lamarck's theory of evolution

  • Theory of use and disuse: organs not in use will disappear while organs in use will develop
  • Theory of acquired characteristics: parent animals could pass on to their offspring the characteristics they had acquired during their lifetime
• Evolution of the giraffe's neck according to Lamarck


  • Giraffes kept stretching their necks to reach tall trees for food, and these acquired characteristics were inherited by their offspring
• Lamarck's ideas were proven to be incorrect - phenotypic changes acquired during an organism's lifetime cannot pass onto next generations
• Charles Darwin's theory of evolution

  Natural selection: giraffe species originally have varying neck lengths but natural selection favored the survival of giraffes with longer necks that could feed on taller trees due to lack of accessible food supply
• Charles Darwin observed that finch species have different beak structures for different food types, and the abundance of certain finch species in an island was related to the type of available food
• Principles of Darwin's theory of natural selection

  • Variation: differences among members of a population that can be passed on to the next generation
  • Overproduction: having many offspring increases the chance that some of them will survive
  • Adaptation: set of genetically acquired traits that make the organism better suited to its environment
  • Survival of the fittest: individuals with advantageous adaptations are more likely to survive and reproduce than those individuals lacking the adaptations
• Natural selection


  Survival of the fittest
• Cutting the cat's tail will not produce kittens without tail
• Phenotypic changes acquired during an organism's lifetime cannot pass onto next generations