Natural Selection and the Evidence of Evolution

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Natural Selection and the Evidence of Evolution

• Section 15.1

1. Offset your 3 papers and make a foldable.
2. Title the top flap the title above
3. Title the Other flaps
4. What is evolution?
5. Darwin-Travels and Influence
6. Natural Selection
7. EvidencesAdaptations, Fossil
8. EvidencesAnatomical, Embyological, Biochemical

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Flap 1--What is evolution?

• The change in populations over time.

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Flap 2--Who is Charles Darwin?

• English scientist/naturalist whose ideas provide
  foundation for the theory of evolution by natural
  selection
• Sailed on HMS Beagle for 5 years studying and
  collecting biological and fossil specimens

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Major Ports of Call

• Galapagos Islands
• Location Near equator, 1000km off west coast of
  S. America
• What he studied many species of animals and
  plants unique to the island, but are similar
  elsewhere
• Major findings Observations led to his
  consideration that species change over time

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Thomas Malthus Influence on Darwin

• Proposed idea that human populations grow faster
  than Earths food supply

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Darwins book

• 1859, The Origin of Species
• Detailed account on his ideas and theories that
  support evolution

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Flap 3Natural Selection

• Realized organisms struggle to compete in
  changing environments. Many types of competition
  exist
• Food and space
• Escaping predators
• Location of shelter

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Insights into why only certain individuals
survive

• Traits vary among populations these traits are
  inherited
• Breeding with others that had desirable traits
  produced offspring with these traits

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Darwins Hypothesis

• Artificial Selection- breeding organism with
  specific traits in order to produce offspring
  with identical traits
• There is force in nature that works like
  artificial selection

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What is natural selection?

• Mechanism of change in populations over time

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The process of natural selection

• Occurs when organism with favorable variations
  survive, reproduce, and pass on their variations
  to the next generation
• Without these variations, organism is less likely
  to survive
• Each new generation thus consists largely of
  offspring with variations aiding their survival

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Flap 4-What are adaptations?

• Variation that aids an organisms chances of
  survival in its environment
• Develop in a species over many generations

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Structural Adaptations Examples

• Teeth and Claws
• Protect against predators
• Mimicry
• Enables one species to resemble another
• Camouflage
• Enables species to blend with surroundings

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Physiological Adaptation

• What are they?
• Changes in organisms metabolic processes
• Example
• After years of exposure to specific pesticides,
  insects and weeds have become resistant

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Fossil Evidence

• Indirect source
• Provide record of early life based upon rock
  layers and location of fossils within them.
• As record becomes more complete, the sequence of
  evolution is clearer

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Example Archeoptryx

• earliest, most primitive bird 145 mya

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Flap 5-Anatomical Evidence
Homologous- common evolutionary origin, features
have similar structure but have different
functions. Ex-bat wing and human hand
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Anatomical Evidence

• Analogous- no common ancestor, but similar in
  function. Organisms like the shark and dolphin
  evolved sleek bodies because they live in similar
  environments, not because they are related.

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Anatomical Evidence

• Vestigial- body structure in present day organism
  that no longer serves original purpose

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Embryological Evidence
The more similar the embryos through out
development the closer the evolutionary
relationship.
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Biochemical Evidence

• Great table on page 403!
• All organisms share DNA, ATP and many enzymes
  among their biochemical molecules . The more
  changes the more time that has passed since they
  shared a common ancestor.