Evidence of Evolution by xiuliliaofz



Evolution: Slow Change Over Time
          I. Charles Darwin
s Charles Darwin (circa 1840) sailed around the
  world for 5 years on the H.M.S. Beagle
Map of Darwin’s Voyages
    2. He observed great
                              a. Birds

          Blue-Footed Booby   Albatross

             Frigate Bird
b. Finches

    Beaks vary based on
      c. Reptiles

                     Marine Iguanas
Galapagos Tortoise
                  d. Plants

Passion Flower Beach Morning Glory   Button Mangrove

                                 Lava Cactus
2. Darwin’s Observations Led
s Ideas to try explain
  what he had seen

s Publishing of “The
  Origin of Species”
      (London, 1859)
                    3. Species
A group of organisms that….
s Look alike

s   Share a common

s   Are capable of breeding

                              Ex: All dogs, same species
     II. Types of Evidence for
s   Fossil Evidence
s   Biogeography
s   Homologous & Analogous Structures
s   Vestigial Structures
s   Embryology
s   Molecular (DNA) Comparisons
               1. Fossil Evidence

Fossil Record:
s A record of ALL fossils ever discovered
s Demonstrates the changes in organisms’
  structures over time caused by changes in
  gene frequency
s Transitional forms (missing links) have been
  found to show relationships between ancient
  forms and modern ones
       Ex: glyptodont
    a. Evolution of
     Modern Horse
From Eohippus (60 mya)
      (5 toes, size of a cat)

To Equus (Modern Horse)
     (1 toe, 4 times as large)
b. Archaeopteryx
     s Known as the most
       important fossil ever
     s Earliest known bird - 150
       million years ago!
     s Transitional form between
       birds and reptiles
     s Features: feathers, “wishbone”,
       wings, and reduced fingers (just
       like modern birds)
 2. Biogeographical Evidence
s a. Convergent Evolution: Unrelated species
  living in different regions of the world with similar
  environmental features happen to look alike
         s Ex: Marsupials (Australia) & Placentals (N.

s Supports natural selection concept: adaptation to
  environmental factors in similar ways (ex: food
   Biogeographical Evidence
b. Armadillo and Anteater have similar structures
       (snout), but are not closely related
  3. Homologous & Analagous

a. Homologous Structures: Structures on
 different species which are similar in form, but
 different in function

  s Structures indicate a shared common ancestor

  s Example: The arm bones of various vertebrate
     s Flipper, arm, or a wing
Homologous Structures
   Homologous & Analagous
b. Analogous Structures
s Features that share identical functions and
  look similar in build due to natural selection

s Internal anatomy is very different; organisms
  are NOT closely related
  Ex: Bird & Insect wings

   Hummingbird               Hummingbird Moth
        4. Vestigial Structures
s Structures that remain on an organism
  which have no purpose, or are not used
  for their original purpose anymore
s Examples:
  s Whale hip bones
  s Ostrich wings
  s Human tailbone, wisdom teeth, appendix
a. Whales have a pelvis (hip bone) and a
femur (upper leg bone), but they have no
       need for them in the water
b. Flightless birds, like this Cassowary and
        Ostrich have vestigial wings
c. The human tailbone or
coccyx doesn’t do much for
• These are “left-overs” from
ancestors who used tails for
balance or communication
like many mammals do
               Human Tails
s Some children are
  born with a full tail
  (since we have the
  genes for it).
d. Human Wisdom Teeth:
•Rear molars that most (but not all) people
must have removed around age 18.
•Left-overs from a larger mouth or a
byproduct of better modern hygiene?
e. The Human Appendix: a vestigial organ that is
still used by other, mostly herbivorous mammals
to help them digest plants in their diet.
  •It is thought to be a leftover from ancestors with a more
  herbivorous diet.

 They commonly
 become infected
 appendicitis and
 must be surgically
   5. Embryological Evidence
s Embryos of different organisms look
  extremely similar at early stages of
  - similarities begin to fade with further
   6. Molecular Comparisons
s The closer an organism is to
  it’s ancestor, the more
  molecular similarities exist
  s Humans/Chimps = 98% the
    same DNA
  s Blood proteins in humans &
    gorillas differ by only one
    amino acid!
     Molecular Comparisons

s One organism’s
  sequences can work
  in another organism
  s Using pigs for
    organ donation in

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