Adj natural selection


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Adj natural selection

  1. 1. Evolution by Natural Selection<br />Hour 2, 2-23-2011<br />
  2. 2. Learning Targets for Evolution<br />8.1 I can define evolution and use the definition to predict where modern organisms have come from.<br />8.2 I can recognize that evolution requires a long period of time to occur. <br />8.3 I can compare artificial selection to natural selection and am able to identify each from examples.<br />8.4 I can identify the two major sources of variation in organisms that reproduce sexually.<br />8.5 I can explain why genetic variation within a population is essential for change over time.<br />8.6 I can list examples of challenges that organisms face in their struggle for existence.<br />8.7 I can explain why organisms compete with one another in order to survive.<br />8.8 I can define the term adaptation.<br />
  3. 3. Learning Targets Continued…<br />8.9 I can predict what will happen when organism’s adaptations are more suited to their environment.<br />8.10 I can describe the difference between an individual and a population and state which is affected by evolution.<br /> 8.11 I can differentiate between the concept of an adaptation and the process of evolution.<br /> 8.12 I can predict how an adaptation will change in frequency within the population over time.<br />8.13. I can use graphical data to describe how the frequency of a particular trait will change in response to different natural selection pressures. <br />8.14 I can explain convergence in terms of how unrelated species respond to similar environmental pressures. <br />8.15 I can use the process of natural selection to explain how divergence and adaptive radiation lead to diverse populations from one common ancestor.<br /> 8.16 I can use co-evolution to explain what will happen to two organisms that are closely connected to each other <br />
  4. 4. Why should we study evolution?<br />
  5. 5. Important Terms<br />Evolution <br />Artificial selection<br />Natural selection<br />Variation<br />Competition<br />Adaptation<br />Convergence<br />Divergence<br />Adaptive radiation<br />Co-evolution<br />Theory<br />
  6. 6. What is a Theory?<br />Theory- a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses<br />
  7. 7. Law- a descriptive generalization about how some aspect of the natural world behaves under stated circumstances and that carries the weight of scientific evidence<br />Fact-an observation that has been repeatedly confirmed<br />Hypothesis- a testable statement about the natural world<br />Belief- a psychological state in which a person holds a premise (or statement) to be true.<br />
  8. 8. Evolution by Natural Selection is a theory<br />Evolution (or change in organisms over time) is a scientific theory; it is a well-substantiated explanation of an aspect of the natural world that incorporates facts (observable phenomena) such as virus and bacterial adaptations, inferences (geological processes have always been happening at a constant rate in the history of the Earth), and tested hypotheses (evolutionary relationships echoed in DNA analysis).<br />
  9. 9. Age of the Earth<br />Earth is about 4.5 billion years old<br />Geologists confirmed this approximate date through determining the age of rock formations and the time it would take for them to form<br />
  10. 10. Why does it matter how old the Earth is?<br />
  11. 11. Time is important:<br />If weathering and other geological processes have been happening at the same rate for a very long time (or always) then the Earth must be several billion years old to account for the formations.<br />Other ways we know:<br />Chemical analysis of ice cores<br />radio active fluorine <br />
  12. 12. Evolution<br />Change in organisms over time<br />These changes are seen in populations not in individuals<br />
  13. 13. Charles Darwin<br />On the Origin of Species in 1859.<br />Darwin supplied evidence that evolution has occurred. He also explained his ideas about how (mechanism) evolution occurs. <br />
  14. 14. Darwin’s theory was based on artificial selection. In artificial selection, nature provided the variation, and humans selected those variations that they found useful.<br /> For example, animal breeders used only the largest hogs, fastest horses, or cows that produced the most milk for breeding.<br />
  15. 15. Artificial Selection<br />Natural Selection<br />Variation in traits exists<br />Breeder selects favorable traits in organism<br />Breeder mates animals with the favorable traits more than other organisms<br />Desired traits become more common in population<br />Variation in traits exists<br />Nature “selects” favorable traits in organism because some of these trait give a reproductive or survival advantage<br />Organisms with favorable traits survive better and have more offspring<br />Traits that give a reproductive/survival advantage become more common in population<br />
  16. 16. Why do both forms of selection require variation?<br />
  17. 17. Sources of variation<br />Genetic Shuffling in Anaphase I of meiosis<br />Mutation to DNA passed down to offspring (very rare!)<br />
  18. 18. What is competition?<br />
  19. 19. Competition<br />Competition is a struggle for limited resources in which there can only be one or a few “winners”<br />On Earth we have a finite number of resources; there are many more organisms than resources.<br />A struggle for survival results, the organisms that get the resources will live and pass on their genes to the next generation.<br />Besides limited resources; what are some other challenges organisms must face to survive and reproduce?<br />
  20. 20. Adaptations<br />Traits that provide some type of advantage to organisms in the struggle for survival are called adaptations.<br />There are recognizable patterns to the way organisms adapt<br />
  21. 21. Predict what will happen to a bunny population with a brown fur mutation in an equatorial environment.<br />
  22. 22. Convergence<br />Unrelated species respond to environmental pressures with similar functional adaptations<br />
  23. 23. Divergence<br />Humans DID NOT come from apes, rather both species had a common ancestor long ago<br />IDA<br />
  24. 24. Draw a diagram of how scientist would describe the relationship between Ida, humans and apes.<br />
  25. 25. Adaptive Radiation<br />Adaptive radiation is the pattern of adaptation that isolates a species into two separate lineages<br />
  26. 26. Co-Evolution<br />Co-evolution is when a species directly influences the evolution of another species and both populations evolve in parallel.<br />