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Lab #2 - Scientific Method, Convergent Evolution, and the Tasmanian Wolf story

Lab #2 - Scientific Method, Convergent Evolution, and the Tasmanian Wolf story. What’s wrong with this image?. “Slow down, look carefully, and things make more sense.” – me. Step 1 is not “observe” …it’s to become an expert, so you can observe critically.

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Lab #2 - Scientific Method, Convergent Evolution, and the Tasmanian Wolf story

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  1. Lab #2 - Scientific Method, Convergent Evolution, and the Tasmanian Wolf story

  2. What’s wrong with this image?

  3. “Slow down, look carefully, and things make more sense.” – me. Step 1 is not “observe” …it’s to become an expert, so you can observe critically. It takes a lot of practice to observe and think of original ideas. Most scientists aren’t even good at it.

  4. Convergent Evolution Hawkmoths Sunbirds Hummingbirds

  5. Evolution via natural selection

  6. What would happen if all of the trees and dinosaurs were the same size?

  7. Individual variation is necessary for natural selection to occur.

  8. What would happen if all the dinosaurs produced just one offspring?

  9. Differential fitness is necessary for natural selection to occur.

  10. What would happen if offspring never resembled their parents? ✖ Parents: Offspring:

  11. Traits must be heritable for natural selection to occur ✖ Parents: Offspring:

  12. Conditions required for natural selection to occur: Individual variation: members of a species differ in their characteristics Mode of inheritance: parents pass on some of their traits to their offspring Differential fitness:some individuals leave more offspring than others due to their special inherited traits

  13. Change in population occurs because of differences in reproductive success. Organisms do not evolve because they want or need to change.

  14. How do organisms converge on certain traits? Change in population occurs because of differences in reproductive success. Total offspring + future generations = “fitness” Organisms do not evolve because they want or need to change.

  15. Case study: Thylacinesand placental wolves This is a canid phylogeny. Notice, there are no Thylacines. Today you’ll be making predictions based on two hypotheses: Both animals were created similarly The animals underwent convergent evolution and evolved similar traits.

  16. Convergence on this suite of termite-eating skills has occurred many times around the world!

  17. CONVERGENT EVOLUTION Example: • Cursorial herbivores pronghorn, capybara, elk, kangaroos, deer In what ways? …digestive tract, dentition, elongated limbs, behavior, perception • What other traits have independently evolved? • Think about the importance of plate tectonics….

  18. Convergent Evolution • BatesianMimcry • Benign species resembles a noxious or dangerous species These bright colors are signals, or“aposematic traits” Question: How could aposematism evolve?

  19. Convergent Evolution • Mullerian Mimicry • Noxious species resemble each other • Pitohui birds in New Guinea Viceroy and Monarch butterflies both taste nasty.

  20. Convergent Evolution • Aggressive Mimicry • Noxious or dangerous species resembles a benign one. • ex. hawks, vultures, kites

  21. Thylacinesand placental wolves Focus on the following today: The differences between carnivore and herbivore teeth and skull morphologies How do you interpret these differences? Give me focused, specific answers. e.g. “Based on many skull characteristics, blah blah…” How does ecology affect the organism’s phenotype? What makes the species different ecologically and morphometrically? 3. While you are encouraged to have opinions, try to remain objective and scientific  And don’t forget about your QHPM. Have fun!

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