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Chapter 22. Descent with Modification: A Darwinian View of Life. Think quietly for a minute…how would YOU define evolution? What was Darwin’s definition of evolution? Did he actually use the term evolution in his book?. Classification of Species. Aristotle (384-322 B.C.) – Scala Naturae
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Chapter 22 Descent with Modification: A Darwinian View of Life
Think quietly for a minute…how would YOU define evolution? • What was Darwin’s definition of evolution? • Did he actually use the term evolution in his book?
Classification of Species • Aristotle (384-322 B.C.) – ScalaNaturae • Carolus Linnaeus- binomial system of naming • What was the main thing that was determining ideas about how species formed up until the 19th century? • Lamarck – first hypothesis on HOW things change…what did he believe?
Paleontology Contributions • Georges Cuvier (1769-1832) • Developed paleontology • Older strata = more dissimilar • Completely against evolution so how did he explain the large changes and differences? • Catastrophism • James Hutton (1726-1797) – gradualism • Charles Lyell (1797-1875) - uniformitarianism
Darwin’s Background • 1809-1882 • Cambridge then HMS Beagle • Beagle Discoveries/Voyage: • Species resembled nearby species rather than species in similar climates elsewhere • Earth is older than previously thought • Galapagos species found nowhere else on earth
The Origin of Species • Adaptations - something that allows an organism to survive better in its environment • Examples? • Adaptation = better survival = more offspring = trait passed on • Natural selection • Described to Lyell…Alfred Russel Wallace publishes similar ideas first
five digits wrist bone Natural Selection • Artificial vs. Natural Selection • 4 principles • Variation • Adaptation • Overproduction • Descent with modification • Key points: • Individual evolution • Heritable traits • Environmental context
Supporting Evidence • Direct Observation • Fossil Record • Actual fossils • Age of fossils • Homology • Homologous structures • Vestigial structures • Molecular homologies • Convergent evolution • Biogeography