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Thinking about Turtles & EvolutionPart 1: How the Turtle Gets its Shell

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Strange Anatomy

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Unique Development

Expanding edge of the carapacial ridge.

A. Entire embryo in cross-section. B. Enlargement.

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Formation of Bonein Turtle Shell

Advantages of Metamerism (repeating body segments)

EndochondralIntramembranous

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Microeveolution by Speciation (Darwin)Macroevolution =

Whole New Body Plans (like turtles)Revision of Text Analogy

Problems with transitional forms in nature

Microevolution vs Macroevolution

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Uniramous &Biramous

Appendages

Mutation andSpecilization

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Gene Regulation: On/Off Switches

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Real world example of Gene Regulation in Prokaryote (E. coli)

Generalize to molecules from adjacent cells serving as signals

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Unique Development

Expanding edge of the carapacial ridge.

A. Entire embryo in cross-section. B. Enlargement.

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Fruit Fly Drosophila melanogaster

Larva (maggot)

Adult

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Embryonic Limb Buds

NormalMutated

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