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Patterns in Evolution

Patterns in Evolution. Divergent Evolution. Defined: closely related species become increasingly different Cause: Differing environments Ex: Red fox (forest) vs. Kit fox (desert). Kaibab Squirrel (Grand Canyon). Convergent Evolution.

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Patterns in Evolution

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  1. Patterns in Evolution

  2. Divergent Evolution • Defined: closely related species become increasingly different • Cause: Differing environments • Ex: Red fox (forest) vs. Kit fox (desert)

  3. Kaibab Squirrel (Grand Canyon)

  4. Convergent Evolution • Defined: different species evolve similar traits due to similar habitats • Survival advantages to particular environments • Ex: Tuna (fish) and dolphins (mammals) • Unrelated species with a similar environment (ocean)

  5. Dragonfly Convergent Evolution

  6. Coevolution • Defined: 2 or more species evolve in response to changes in each other • Ex: Plants and Insects • Plants: provide insects with nectar • Insect: transfers pollen from one plant to another

  7. Hummingbirds: Beak shape depends on flower shape

  8. Extinction • Background Extinctions: • Less severe; local level • Forest fires, habitat destruction • Mass Extinctions: • Very severe; global level • 5 identified in earth’s history (volcanic activity, meteor strikes)

  9. How Fast Does Evolution Occur? • No exact time frame • Gradualism: slow & steady change of 1 species into another • Small changes continually build • Punctuated Equilibrium: Rapid periods of evolution • Due to sudden environment change • Ex: Mammal diversity exploded after dinosaur extinction • Examples of both models exist

  10. Gradualism of the Horse

  11. Kobe Kuiz • How is convergent and divergent evolution different? • What is thought to bring different organisms such as fish and dolphins to have evolved a similar body plan? • What is coevolution? • What does a flower gain from a close relationship with a hummingbird? • What does the hummingbird gain? • How is gradualism and punctuated equilibrium different?

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