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(Survival of the Fittest)
DARWIN’S THEORY of NATURAL SELECTION (Survival of the Fittest)
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HOW DOES NATURAL SELECTION LEAD TO EVOLUTION?
In this section you will want to find the answers for: HOW DID DARWIN EXPLAIN THE DIFFERENCES BETWEEN SPECIES ON THE GALAPAGOS ISLANDS AND ON MAINLAND SOUTH AMERICA? HOW DOES NATURAL SELECTION LEAD TO EVOLUTION? HOW DO NEW SPECIES FORM?
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In 1831, Charles Darwin set sail on the HMS Beagle for a 5 year trip around the world
Darwin collected and studied numerous marine organisms during this famous voyage...
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Observations he made on the Beagle expedition also provided him with the ideas that he later used to formulate his theory of evolution and natural selection.
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Group of similar organisms that can mate and produce offspring
VOCABULARY SCIENTIFIC THEORY: a well tested concept (idea) that explains a wide range of observations What is the difference between an idea, theory and fact? SPECIES: Group of similar organisms that can mate and produce offspring
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DARWIN’S THEORY: Species gradually change over many generations and become better adapted to new conditions
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THE GALAPOGOS ISALNDS ARE A GROUP OF VOLCANIC ISLANDS
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HOW DID DARWIN THINK PLANTS...
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...AND ANIMALS ORIGINALLY CAME TO GALAPAGOS ISLAND?
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Ancestors of today’s plants & animals on the islands were brought from the mainland by wind, currents, or on floating debris...
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FROM MAINLAND RELATIVES DUE TO RESOURCES AVAILABLE.
ONCE THEY REACHED ILSANDS, THEY REPRODUCED & OFFSPRING BECAME DIFFERENT FROM MAINLAND RELATIVES DUE TO RESOURCES AVAILABLE. Island Turtles Mainland Turtle
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THIS BRINGS US TO DARWIN’S THEORY OF NATURAL SELECTION
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Natural Selection Individuals that are better adapted to their environment are more likely to survive.
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SURVIVAL OF THE FITTEST
WHAT ARE FACTORS THAT AFFECT SURVIVAL? Differences in species (variations) Over production of same species Competition for resources
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HOW DOES THIS APPLY TO THE GALAPAGOS ISLANDS?
SO…. HOW DOES THIS APPLY TO THE GALAPAGOS ISLANDS?
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Organisms that were on the Islands first had NO competition for resources (food, shelter, H2O) because no other species was there.
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Darwin studied finches found on these islands
Darwin studied finches found on these islands. This played an important role in his recognition of the evolutionary process.
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by studying the finches - Darwin
showed how species are related to other species
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over long periods of time natural selection can lead to evolution.
...And over long periods of time natural selection can lead to evolution. VARIATIONS IN ORGANISMS GRADUALLY ACCUMULATE WHILE UNFAVORABLE ONES DISAPPEAR. HOW?
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As you can see in the next photos, Darwin's finches share similar size color, and habits - the difference is size and shape of their beak.
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The F I N C H E S
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WARBLER FINCHES
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Lava Finch Galapagos Volcanoes
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WHAT ARE SOME OTHER WAYS NEW SPECIES COULD HAVE FORMED?
CONTINENTAL DRIFT
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SEPARATION by: RIVERS
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SURVIVAL of the FITTEST
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How is each organism suited to play a certain role in a certain habitat?
ADAPTATIONS: inherited features that let organisms survive & produce young
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Camouflage: Adaptations that allow organisms to blend in w/environment.
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What’s right w/these pics?
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What’s the problem here?
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What’s wrong w/this pic?
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ANOTHER ADAPTATION SEEN IN ANIMALS AND PLANTS:
MIMICRY
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KING SNAKE
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CORAL SNAKE
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WHICH IS WHICH? CORAL KING
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WHAT MAKES AN IDEA A THEORY?
CRITICAL THINKING WHAT MAKES AN IDEA A THEORY? HOW IS A THEORY DIFFERENT FROM A FACT? UPON WHAT FACTS DID DARWIN BASE HIS THEORY OF EVOLUTION?
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