Bio1_23_EvolutionIII - 1 2 3 1 2 4 5 1 2 6 7 Self-Quiz 1....

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1 Self-Quiz 1. What is directional selection? Disruptive selection? Stabilizing selection? 2. How can sexual selection lead to dimorphic sexes? 3. What role does the environment play in maintaining diversity? 5. Give examples of adaptive radiation. Overview • Ch. 17: Macroevolution – The Burgess Shale – Principles of macroevolution • Ch. 18: History of Life – Section 18.2: Fossil record The Burgess Shale • Marine life ~ 540 mya – Cambrian explosion – Highly diverse • Ancestors of all modern animal groups Macroevolution • Evolution at higher levels of classification – Gradualistic model: slow change over time – Punctuated equilibrium model: rapid change •Periods of no change interrupted by speciation •Transitional links less likely to be found – Both models used in interpreting fossil record •Remember “sudden” = many thousands of years Macroevolution • Gradualistic model • Punctuated equilibrium model Developmental Genes – All animals share the same control switches for development Pax6: eye development Tbx5: Hox: • Patterns of macroevolution • E.g., evolution of the horse – Trends: size,
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Bio1_23_EvolutionIII - 1 2 3 1 2 4 5 1 2 6 7 Self-Quiz 1....

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