Download Notes Outline: Evolution and Natural Selection (9

Notes Outline: Evolution and Natural Selection (10.1)
“Our earth is rich in life. About 1.4 million species have been named and millions more are thought
to exist. Why are some species more alike than others? Were they all created at once, or have species
evolved? These questions have been asked for thousands of years, but it was not until 1859 that the
work of Charles Darwin offered answers.”
I.
Charles Darwin
A. Voyage of the Beagle
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Dec. 27, 1831 Charles Darwin sailed on the H.M.S. Beagle.
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As a medical student, he skipped lectures to spend time collecting biological specimens.
In desperation his father sent him to Cambridge University to train to be a minister.
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Darwin, like most people of his time, believed in Creationism.
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Creationism = idea that God was responsible for the creation of new species.
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Moreover, creationists believe that species are unchanging.
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Darwin’s observations led him to doubt creationism.
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B. Darwin’s Finches
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Darwin repeatedly saw patterns in how kinds of animals and plants differed
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Patterns suggesting that species changed over time and gave rise to new species.
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On the Galapagos Islands, Darwin collected several species of finches.
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All these species were similar, but each was specialized to catch food in a different way.
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All the species of finches closely resembled one species of South America finch.
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If each one of these animals had been created to match the habitat on the Galapagos
Islands, why did they not resemble the animals of islands with similar environments that
lie off the coast of Africa? Why did they instead resemble those of the adjacent South
American continent?
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Darwin explained that a few organisms from South America must have migrated to the
Galapagos Islands in the past.
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These animals changed over time in their new home, giving rise to many new species.
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Change in species over time is known as Evolution.
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C. Darwin’s Mechanism for Evolution
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Darwin published his controversial book, On the Origin of Species by Means of Natural
Selection in 1859
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Darwin’s conclusion that species changed over time and gave rise to new species
contradicted the prevailing beliefs that God created all living things and that living things
did not change.
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Natural Selection: Process by which organisms with traits well suited to an environment
survive and reproduce at a greater rate than organisms less suited to that environment.
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Mendel’s ideas about genetics were added to Darwin’s ideas, forming the modern
principle of evolution.
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