Chapter 13

Theory of EvolutionChapter 13Charles Darwin1831 sent as a naturalist on the HMS Beagle to survey the South American coastStudied animals and plants encountered on the journeyHe was struck by the fact that the plants and animals of the Galapagos Islands resembled (but were not the same) those of the south American coastThe separation had caused a gradual change in the organismsCharles Darwin

Where he went

What he saw

Existing theories of changeMany people believed that each creature existed as it was created, meaning every organism today would have looked the same millions of years ago

A new Idea

Jean Baptiste Lamarck: he proposed that organisms can change over their lifetimes by the use or non-use of certain body parts

Example: how the giraffes neck became long

Main Points of Darwins Theory1. Variations of genes exist in every population2. In a population, some individuals are better suited for survival3. Over time, beneficial traits tend to spread4. The fossil record shows that living species evolved from extinct onesTerms to definePopulationNatural selectionAdaptationReproductive isolationGradualismPunctuated equilibrium

Homework: Read Chapter 13 sections 1-2 and define the above terms