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Bellwork

Bellwork. Imagine that you are traveling in Madagascar when you find the plant to the left . You see that the plant has an

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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. KEY CONCEPT Evolution occurs in patterns.

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

  4. 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 

  5. Coevolution

  6. 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.

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

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

  9. The Star Orchid and the Hawk Moth

  10. Mimicry is another example of coevolution • Mimicryoccurs 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

  11. Convergent Evolution

  12. 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

  13. Divergent Evolution

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

  15. Changes in the frequency of a gene in the gene pool initially leads to microevolution. Microevolution refers to a small change in a population over a short amount of time.Many small changes eventually lead to macroevolution. Macroevolution refers to the sum total of many changes that transform organisms over a long period of time.Macroevolution leads to speciation or the creation of a new species. When an evolving population can no longer interbreed with the original population, a new species is formed.

  16. 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?

  17. 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? coevolutionconvergent 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

  18. WHICH PATTERN IS IT? coevolutionconvergent 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

  19. WHICH PATTERN IS IT? coevolutionconvergent 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

  20. Beaver Beaver Muskrat Beaver andMuskrat Coypu NORTH AMERICA Muskrat SOUTH AMERICA Capybara Coypu WHICH PATTERN IS IT? coevolutionconvergent 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. Adaptive radiation OR divergent evolution BIOLOGY by Miller and Levine Pearson Publishing

  21. WHICH PATTERN IS IT? coevolutionconvergent 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

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