Chapter 15.2

Remodeling

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Refinement

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All organisms have adaptations for their environment

Complex structures usually come from evolution of similar

basic things

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Output: Brainstorm (Eyes) (1/2 pages)

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1. What are the functions of eyes in animals?

2. How do these functions differ in usefulness in a

variety of animals (ex. owls, moths, fish, houseflies,

rabbits, earthworms, and humans)?

3. How does an eye evolve to be so complex?

Output: Homologous Structures (1/2 page)

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Identify the homologous (or similar structures) present in at

least three of the mammals

Structure Bat Human Dog Seal

Fore limbs Yes Yes yes yes

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You can find animals (ex. mollusks, squids, octopuses, snails,

and clams) with very simple light sensing organs

They survive fine with simple organs that identify light from

dark

No need to evolve straight from simple to complex

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Adaptation of existing features

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Existing materials and structures have evolved to serve

different functions

Ex. Arthropod (ex. Spiders, scorpions, and lobsters) -

exoskeleton started in ocean to protect them from predators

-on land it protects them from dehydration and water loss

Ex. Penguins’ wings now act like flippers

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Evolution and Development

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EMBRYOLOGY is the study of organisms as the change from

fertilized eggs to full organisms

You can see patterns in change based on genetic expression

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Example of remodeling process with different timing

The difference in the feet of tree vs. ground salamanders is a

great example

Tree salamanders have shorter toes because they start

developing toes later than ground salamanders

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