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

1

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

2

Strange Anatomy

3

Unique Development

Expanding edge of the carapacial ridge.

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

4

Formation of Bonein Turtle Shell

Advantages of Metamerism (repeating body segments)

EndochondralIntramembranous

5

Microeveolution by Speciation (Darwin)Macroevolution =

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

Problems with transitional forms in nature

Microevolution vs Macroevolution

6

Uniramous &Biramous

Appendages

Mutation andSpecilization

7

Gene Regulation: On/Off Switches

8

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

Generalize to molecules from adjacent cells serving as signals

9

Unique Development

Expanding edge of the carapacial ridge.

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

10

Fruit Fly Drosophila melanogaster

Larva (maggot)

Adult

11

Embryonic Limb Buds

NormalMutated

12