Theory of Evolution

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Theory of Evolution

• Slow Change over time

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I. Fossil Record

• A. The fossil record of Earth shows evidence that
  species of living things have undergone perpetual
  changes, caused by changes in gene frequency.
• B. Changes in gene frequencies ?
• new species

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C. E.g. Evolution of the modern horse

• From Eohippus
• (5 toes, gt 1 foot,
• size of a cat)
• To Equus
• (1 toe,
• 5 feet or more
• at the withers)

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E.g. Evolution of the modern horse
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D. Charles Darwin

• 1. Circa 1840, Charles Darwin sailed
• around the world for 5 years on
• the HMS Beagle.

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2. Voyages of the HMS Beagle
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3. He observed great biodiversity.
Penguin
a. E.g. Birds
Blue-footed booby
Albatross
Frigate bird
Galapagos dove
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b. Finches
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c. Reptiles
Galapagos tortoise
Marine iguana
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d. Plants
Capparidaceae
Button mangrove
Achupalla plant.
Beach morning glory
Passion flower
Passion flower
Aristolochia
Lava cactus
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4. Darwins observations lead to

• a. Ideas to try explain what he had seen.
• b. Publishing of
• The Origin of the Species

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5. Ideas contributing to the theory of evolution

• a.Evolution slow change over time, sometimes
  causing new species to emerge
• b. Species a group of organisms that
• look very much alike
• share a common ancestry
• are capable of breeding and producing viable
  offspring that are capable of reproducing

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b. Species

• E.g. all dogs, same species
• However, horse donkey mule

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c. Natural selection

• i. Species members survive if they have the
  genes that are best suited for the current
  environmental conditions.
• ii. Species unable to adapt to the current
  conditions become extinct.

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c. Natural selection

• iii. Nature selects for advantageous traits
  (genes) and against traits that do not improve
  a species chances of survival.
• iv. Individuals with advantageous traits survive
  to breed and pass those traits to the next
  generation.

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c. Natural selection

• v. Gene frequency changes are caused by natural
  selection.
• vi. Natural selection may lead to evolutionary
  change.

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vii. The Peppered Moth (an example of natural
selection)
Light Form of peppered moth
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vii. The Peppered Moth

• Facts
• Pre-Industrial revolution (late 18th early 19th
  Centuries), ratio of light peppered moths to
  melanic (dark) was 5050

Light and melanic (dark) forms
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vii. The Peppered Moth

• Industrial Revolution, coal burning by factories
  caused tree trunks to become dark- colored.
• Bird predators ate more light moths, more melanic
  moths survived.
• light moths lt
• Melanic moths

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g. The Peppered Moth

• By the 1950s, coal burning stopped.
• Ratio of light to melanic returned to 5050.
• Moths did NOT change color.
• Both colors always existed in the gene pool.
• Gene frequencies changed.

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4. Adaptation

• an anatomical structure, physiological
  process, or behavioral trait that improves an
  animals fitness for survival

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5. Common descent

• all life forms come from some
• original
• life form
• closely related species have a common ancestor

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6. Homology

• a. similarity of organisms due to common
  embryonic or evolutionary origin
• b. E.g. a vertebrate forelimb could be an arm, a
  wing, or a flipper
• made of same bones
• may have different f(x)s

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c. Homologous structures
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humerus
radius ulna
metacarpals
carpals
bat
mole
human
whale
bird
horse
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7. Adaptive Radiation

• production of ecologically diverse species from
  a common ancestral stock

• (see text figure 1.17)

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8.Extinctions

• AT LEAST five major extinctions
• in geological time
• 65 million years ago during the Cretaceous era,
  what animal group become extinct?
• Why?

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8. Extinctions

• Dinosaurs. Unable to adapt to the changing
  environmental conditions (did not have the gene
  combinations to permit their survival

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E. Rapid evolution?

• 1. Antibiotic use creating super germs
• 2. Use of pesticides creating super bugs