Natural and Artificial Selection - PowerPoint PPT Presentation

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Natural and Artificial Selection

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  1. Natural and Artificial Selection Standard: 7.a. Students know why natural selection acts on the phenotype rather than the genotype of an organism

  2. Artificial selection- humans select which traits will be passed on Natural selection- the environment determines which traits will be passed on Struggle for existence- organisms fight for resources Fitness- best traits for the environment Adaptation- an INHERITED good trait Survival of the fittest- those organisms best suited to the environment will survive and reproduce

  3. What do you need to survive? How did squids acquire this ability? Why? http://www.youtube.com/watch?v=5Il14q63sv4

  4. Imagine you are an ancient species of giraffe… • Goal: Eat the leaves on the tree. But there are rules. • Tall Giraffes eat first • Can only eat 5 leaves at a time • Can not hop, jump or stand on tippy toes or any other object. (like a chair) • As soon as leaves are out of reach sit down. • Must take turns. 1 at a time. • Do not throw leaves away • Do not exhort yourself. Eat the easiest leaves to get first.

  5. NATURAL SELECTION ACTS ON THE PHENOTYPE, NOT THE GENOTYPE!! It only matters how the organisms traits are expressed- nature doesn’t know exactly what the genes are inside, only what it looks like or acts like This giraffe could be TT or Tt- you cannot tell from the outside!!!

  6. Artificial selection/selective breeding • Darwin noticed that humans “selected” and bred certain plants and animals to get the desired traits. • Nature provides the variation. Humans choose the most useful.

  7. In your own words what is the difference between natural and artificial selection? http://learn.genetics.utah.edu/content/variation/artificial/ Natural vs artificial

  8. The ability of an individual organism to survive and reproduce in it’s natural environnent iscalledwhat? • Evolution • Natural Selection • Adaptation • Fitness

  9. Thumbs Check I understand it 100% and don’t need anymore examples. I kind of understand it. And could use some more examples. I do not understand what is being taught. I could benefit from it being explained differently and maybe more examples.

  10. The corn most of us eat today is very different from it’s ancestor. This is a result of what? • Fitness • Adaptation • Artificial Selection

  11. Natural Selection • He also noticed that some organisms in nature were “selected” to survive and reproduce in certain environments Example: Finches on different islands looked so different from one another because their beaks were shaped to eat different foods (in different habitats).

  12. Descent with Modification Darwin also believed that natural selection produced organisms with different structures, niches, and habitats

  13. Survival of the Fittest • Members of a population that have desirable traits (the most “fit”) will have a greater chance to survive and reproduce in that environment. • The most “fit” will be “selected” to thrive, reproduce, and survive. • Those with less desirable traits will be “selected” to die or leave fewer offspring. http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html hummingbirds

  14. Thumbs Check I understand it 100% and don’t need anymore examples. I kind of understand it. And could use some more examples. I do not understand what is being taught. I could benefit from it being explained differently and maybe more examples.

  15. Quick Check • How is Natural Selection related to species fitness?

  16. The ability of an individual to survive and reproduce in its environment is called fitness. An adaptation is any INHERITED characteristic that increases an organism’s chances of survival. EVOLUTION takes place over a period of time. And is used to describe entire generations not simply individuals.

  17. Quick Check Fitness is a result of • Going to the gym • Adaptations • Artificial Selection • Natural Selection

  18. Thumbs Check I understand it 100% and don’t need anymore examples. I kind of understand it. And could use some more examples. I do not understand what is being taught. I could benefit from it being explained differently and maybe more examples.

  19. Risk Box In 5 generations of birds, some were able to survive and reproduce better than others. Give some possible reasons why it might be more difficult for the lighter birds to survive and reproduce?

  20. Watch this: http://www.pbs.org/wgbh/nova/evolution/evolution-action.html evolution interaction • What to put on the notecard: • Observations • Questions

  21. Natural Selection in Lizards Practice

  22. Activity Procedure • Work in groups of 3 to 4 • 2 predators and 1-2 recorders • Spread the news paper on the table • Predators stand and turn with their backs to the table. (do not turn around) • Recorders randomly spread the squares(lizards) on newspaper • Make sure no squares overlap

  23. Steps Cont. • Predators quickly turn around and grab one square off the table • Hand the square to the recorder • Turn back around • Repeat steps until five lizards (squares) have been pulled (end of trial)

  24. Steps Cont. • At the end of each trial record how many of each lizard is still alive in the data table. (Columns B and C) • When finished with Trial 4 raise hand in air

  25. Steps after the Flood (Trial 5-8) • Cover newspaper with brown paper • Repeat same steps as before until finished. • Use data collected to complete the data table • Graph your percentages(%) using 2 colors

  26. What is the definition of a species? Members of the same species can successfully reproduce. Descent with modification: Every living species has evolved, over time, with changes, from other species

  27. Common descent: all living organisms are related

  28. Watch this: http://learn.genetics.utah.edu/content/variation/recipe/

  29. Q: Which of these best illustrates natural selection? An organism with favorable genetic variations will tend to survive and breed successfully. B. A population monopolizes all of the resources in its habitat, forcing other species to migrate. C. A community whose members work together utilizes all existing resources and migratory routes. D. The largest organisms in a species receive the only breeding opportunities.

  30. Q: A species of finch has been studied on one of the geographically isolated Galapagos Islands for many years. Since the island is small, the lineage of every bird for several generations is known. This allows a family tree of each bird to be developed. Some family groups have survived and others have died out. The groups that survive probably have A. interbred with other species. B. inherited some advantageous variations. C. found new places on the island to live. D. been attacked by more predators.

  31. Advantage- something that helps Disadvantage- something that harms

  32. Peppered moths – natural selection in action • Two forms- one dark, one light. • In less polluted areas with cleaner bark on trees and buildings, the light moths were better camouflaged, and were more likely to pass on their light genes • In heavily polluted areas, the dark moths were more common because they were better camouflaged. • This shows that the environment can causes changes in species over several generations. Next slide

  33. Time for a POP QUIZ!!!

  34. Evidence for evolution Fossil record: what are fossils, How old is the Earth? How can scientists use fossils to document (record) the fact that life on Earth has changed over time? Have all the fossils been found? http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html Whales

  35. Geographic distribution of living things: Why were there so many differences between the finches on the Galapagos? What is it called when species evolve, over time, with changes, from other species? What did Darwin find on different continents, but in similar habitats?

  36. Homologous body structures: how are certain body parts similar (in animals with backbones)? How and why have their limbs adapted? Give examples of homologous structures. What are vestigial organs?

  37. Similarities in Embryology: How do the early-stage embryos of vertebrates compare to each other? What do these similarities mean? How do embryonic cells develop? What do they develop into? http://www.pbs.org/wgbh/nova/evolution/guess-embryo.html guess the embryo

  38. Genetic variation: differences in alleles and genes within and among populations (all lions are not exactly alike, all beetles, pine trees, humans, giraffes- are not exactly alike.

  39. Genetic variation is caused by • Mutations • 2. Gene shuffling during sexual reproduction- during meiosis and crossing over • 3. Gene flow, or migration

  40. Evolution is any change in the relative frequency (percentage) of alleles in a population Gene pool- all the alleles in a population

  41. What is the definition of a species? Members of the same species can successfully reproduce. Whale evolution: http://www.youtube.com/watch?v=8cn0kf8mhS4&feature=related