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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