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Evolution

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					Evolution Essential ?s
• How & why have species changed with time?

• What is the benefit & value of evolution?

• How can the theory of evolution be applied to
  today?

• What evidence & thought have contributed to
  the theory of evolution?
    Evolution
Change in genetic make-up over
             time
   Process by which modern
organisms have descended from
      ancient organisms
     The History of the
Development of Evolutionary
         Thought
       1stHypothesis
        Use & Disuse
Jean – Baptiste
   Lamark

      1809

French naturalist
• Tendency Towards Perfection & Complexity
  • organisms continually change to become better
    adapted to their environment & improve survival


• Use & Disuse of Organs
  • structure that are used frequently will become
    larger and be more developed during a lifetime

  • structures not used will become weaker or disappear
    (vestigial organs) during   a lifetime

• Inheritance of Acquired Traits
  • newly acquired traits can be passed on to offspring
Evaluation of Lamark’s Theory
• Incorrect because…..
 • acquired traits (those gained during an organisms
   lifetime) are NOT inherited

 • acquired behaviors CANNOT develop heritable
   characteristics


• Correct because….
 • organisms adapt to their environment overtime to
   increase survival
2nd   Hypothesis
           Natural
          Selection
          Charles
          Darwin

            1831
   Voyage on the H.M.S. Beagle
    The Trip around the World
• Observed many various organisms

• Researched their patterns of diversity

• Studied living organisms & fossils

• Concluded that the earth is constantly
  changing
   The Galapagos Islands
• Most influential location to Darwin’s
  development of the theory of evolution
• 13 small islands off the
  West coast of South
  America by Ecuador
    • Close proximity
    • Extremely diverse
      climates & environments
    • Isolated from each other
• Organisms on each island vary greatly in
  characteristics to be specialized & better
  adapted to their diverse environments
Darwin’s Theory of Evolution




      Published in 1931
   “The Origin of Species”
        Natural Selection
• Organisms varying in inheritable characteristics
 (mechanics of genetics was unknown at this time!)
• Large population size causes competition for
  resources & restricts survival rate
    Natural
   Selection
• Organisms with traits
  that are better “fitted”
  or adapted to their
  environment survive
  and reproduce more
  successfully passing on
  their superior genes to
  the next generation
• Fitness
  • resulting adaptations that
    increase the survival of an
    organism


• Adaptations
  • any inherited
    characteristic that
    increases an organism’s
    survival


“Survival of the Fittest”
Descents with Modification
• Over many successive generations:
  • pressures of natural selection
  • change traits of a population
  • increase overall fitness of the population


• Species evolve:
  • differences in structures & niches
  • resulting in the formation of a new species
  • remaining related to each other by a
    common ancestor
3 Types of Natural
    Selection
 Stabilizing Natural Selection
• Nature eliminates both extreme traits

• Nature favors average traits

• Graph narrows
  increasing the
  number of
  species with
  the average trait
 Directional Natural Selection
• Nature eliminates only 1 extreme trait
• The other extreme trait is favored
• Graph & population diversity shifts toward
  favored trait
Distributive Natural Selection
• Nature eliminates the average trait & favors
  the extreme traits

• Graph & population diversity shifts towards
  the 2 extreme traits

• Possibly
  leading to
  creating
  2 new
  species
Finches of the Galapagos Islands
Darwin’s most famous discoveries came from his
observations on the variations of finch species on
             the Galapagos Islands




 which had extremely diverse and extensive gene
    pools, supporting his theory of evolution
• All of the Finches from the Galapagos Island
  evolved from the same founder species

• The Finches
  were separated
  to different islands
  over several years

• On each island they
  experience different
  natural pressures
• Finches on each island developed variations to
  make them better adapted to their different
  environments of each island

• Eventually the
  Finches became
  specialized and
  different from each
  other becoming
  separate & new
  species on
  each island
Finch’s of the Galapagos Islands

				
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posted:8/31/2012
language:English
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