Download - Chapter 15
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Chapter 15
Darwin’s Theory of Evolution
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Charles Darwin
• Charles Darwin- the father of evolution (1809-1882).
Darwin traveled around the world for 5 years on the HMS Beagle. He collected data and made observations of many unique organisms.
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Darwin’s Journey
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Pinta IslandIntermediate shell
Pinta
Isabela IslandDome-shaped shell
Hood IslandSaddle-backed shellHoodFloreana
Santa Fe
Santa Cruz
James
Marchena
Fernandina
Isabela
Tower
Giant Tortoises of the Galápagos IslandsSection 15-1
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Hutton and Lyell
• Proposed that the earth rocks moved up beneath the earth.
• This process is extremely slow.• The conclusion was that earth is extremely old.• Lyell said that the only way to explain what
occurred in the past is to use processes that occur today.
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Sea level
Sedimentary rocks form in horizontal layers.
When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers.
As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed.
New sediment is then deposited above the exposed older rock surface.
Movement of Earth’s Crust
Section 15-2
Sea level
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Lamarck
• Recognize living things change.
• Proposed his own evolutionary hypothesis.
• 1. Tendency towards perfect.
• 2. Use and disuse.
• 3. Inheritance of acquired traits.
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Figure 15–7 Lamarck’s Theory of EvolutionSection 15-2
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Origin of Species
• Was published 25 years after his famous voyage.
• He was prompted by Alfred Wallace’s work.
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Darwin’s Conclusions
• Artificial selection helped spur the creation of new species.
• Example: breeding of fast horses.
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Darwin’s Conclusions
• Natural selection had no human involvement.
• All life goes through a struggle to exist.
• The genes that allowed an organism to survive would be passed to another generation.
• Over time a new species would develop.
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Evidence of Evolution #1
• Fossil Record
• Showed through the process of time the animals that existed on the planet.
• By comparing fossils and rock layers one can find the relationships in changing life.
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Evidence: Fossils
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Evidence of Evolution #2
• BIOGEOGRAPHY: Geographic Distribution• Different continents had different species of
animals.• The reason is because each species descended from
different animals.• However if the species had the same conditions on
two different continents they evolved the same.
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Beaver
NORTH AMERICA
Muskrat
Capybara SOUTH AMERICA
Coypu
Geographic Distribution
Beaver
Muskrat
Beaver andMuskrat
Coypu
Capybara
Coypu andCapybara
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Evidence of Evolution #3
• COMPARATIVE ANATOMY
• Homologous structures
• Structures in different species that share similar structure, function, or both.
• These show that the species have a common ancestor.
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Turtle Alligator Bird Mammal
Ancient lobe-finned fish
Homologous Body Structures
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Homologous Structures
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• Vestigial structures- A structure that has no function in a present-day organism but was probably useful to an ancestor.
• Natural selection does not get rid of the organ.
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Evidence of Evolution #4
• EMBRYOLOGY
• Embryo- the earliest stage of growth of an organism.
Fish chicken rabbit human
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Embryology
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Evidence of Evolution #5
• MOLECULAR BIOLOGY
• DNA and proteins are shared in common between related individuals.
• Species that are closely related will have higher amounts of their DNA and proteins in common. Ex – Humans and chimps share 99% of their DNA!
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A summary of Darwin’s Theory
• 1. Individual organisms are different and some of these difference can be inherited.
• 2. Organisms produce more offspring than can survive in an environment. The organisms that do not survive do not reproduce.
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A summary of Darwin’s Theory• 3 Because more organisms are produced than
survive, they compete for resources.• 4. Organisms has different advantages and
disadvantages in their struggle for existence. The organisms that are best suited to their environment survive and reproduce a lot more.
• 5. Species alive today are descended with modifications from ancestral species that lived in the past.