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Bellwork

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Bellwork

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  1. Bellwork Imagine that you are traveling in Madagascar when you find the plant to the left. You see that the plant has an unusually large spur containing nectar in its tip. You remember learning in science class that some moths feed on nectar.Draw a picture of what you think a moth may look like that feeds on this plant. Spur • How might natural selection bring about the evolution of this orchid and the moth?

  2. Today’s WHAT: I will evaluate and analyze mechanisms and patterns of evolution.Today’s HOW: I will write notes. I will read and discuss scenarios with a partner.

  3. KEY CONCEPT Evolution occurs in patterns.

  4. REMEMBER: Evolution through natural selection is not random. • Natural selection can have direction. • The effects of natural selection add up over time.

  5. The 3 patterns we’re going to discuss today are: • Coevolution • Convergent Evolution • Divergent Evolution • We’ll also look at how these might be seen in the fossil record 

  6. Coevolution

  7. Co-evolution • Sometimes organisms that are closely connected to one another by ecological interactions evolve together. • An evolutionary change in one organism may also be followed by a corresponding change in another organism. • The process by which two species evolve in response to changes in each other over time is called coevolution.

  8. Coevolution Species A evolves an adaptation in response to species B Species B evolves in response to the adaptation of species A

  9. Coevolution can occur with species that help or compete with each other

  10. The Star Orchid and the Hawk Moth

  11. Mimicry is another example of coevolution • Mimicry occurs when one organism evolves to look like the other in order to benefit itself. The mimic benefits from the situation while the organism it mimics in unaffected. Example: Orchid flowers that mimic female wasps

  12. Convergent Evolution

  13. Convergent Evolution • Convergent evolution describes evolution toward similar traits in unrelated species. • When two species are similar in a particular characteristic, it’s only convergent evolution if their ancestors were not similar

  14. Divergent Evolution

  15. Divergent evolution describes evolution toward different traits in closely related species. • Divergent evolution can lead to speciation. kit fox red fox ancestor

  16. leads to leads to leads to

  17. How does this affect the fossil record??

  18. So what about the fossil record… Things to Consider: • Stasis - The organisms in the fossil record looks the same from when they appear to when they disappear; • Sudden appearance - When a species does not arise by gradually changing steadily from its ancestors; it appears all at once and fully formed. • Sequential nature – Based on the layers of rock, we sequence organisms in the fossil record. • What might cause stasis or sudden appearance?

  19. http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T014608A.gifhttp://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T014608A.gif WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution The Galápagos finches evolved through natural selection from a common ancestor into a wide variety of different looking species with different kinds of beaks divergent evolution

  20. WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution Hummingbirds have a beak just the right length to reach the nectar in a cardinal flower and as they feed their foreheads bump into the pollen structure. Cardinal flowers are red which hummingbirds can see, but bees can’t, and their pollen structure is at just the right height for the hummingbird to pick up pollen as it feeds. coevolution

  21. WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution Whales, sharks, and penguins all have streamlined bodies and fins/flipper for moving in water even though they belong in different animal groups (mammals, fish, and birds) Convergent evolution

  22. Beaver Beaver Muskrat Beaver andMuskrat Coypu NORTH AMERICA Muskrat SOUTH AMERICA Capybara Coypu WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution Beaver in North America and capybara in South America are closely related species living in very different environments that have evolved to look differentover time. divergent evolution BIOLOGY by Miller and Levine Pearson Publishing

  23. WHICH PATTERN IS IT? coevolution convergent evolution divergent evolution The tortoises on the Galapagos islands share a common ancestor, but over time they have become adapted for obtaining food in different habitats on different islands by having different neck lengths divergent evolution