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Similar bone and muscle structures in different organisms, used differently; same bones in human forearm, bat wing, pig front leg, etc...
Darwin's 5 Ideas about Natural Selection
- 1. Organisms produce more offspring than could possibly survive.
- 2. All organisms face a struggle to survive.
- 3. In any given species the offspring will have variations both physically and biochemically that may be benefits or disadvantages to survival in the environment.
- 4. Individuals who have favorable variations and fit into the environment survive.
- 5. The individuals who are best fit and survive reproduce and pass on their genes to their offspring.
Organs with the same function in the same environment (wings for in the air), but which originate from different places (bats, butterflies, birds)
Ear muscles, leg buds on a boa, tailbone, etc... once useful structures which have mostly disappeared since they are no longer useful.
Explain Convergent Evolution.
Plants and animals move into a similar environment and develop similar traits. Frogs, otters, turtles---------similar environment= developed similar traits.
Explain Divergent Evolution.
A family of animals changes to fit its different environments. Deer= elk, moose, caribou, gazelles, ibexes, etc... Each animal fits in a different niche.
Steps of Speciation
- 1. Barrier to gene flow:
- Bottleneck & Founder Effects
- 2. Differential Selection:
- Differences in environment, natural selection, mating times, and other things
- 3. Too different to interbreed:
- Too genetically dissimilar after independent evolution
Structural vs. Functional Proteins
Structural proteins make up body parts of an organism: skin, muscle, etc...
Functional Proteins make the structures work--blood, enzymes, hormones, etc...