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10 25-11


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10 25-11

  2. 2. Quick Review…. <ul><li>What is adaptation? </li></ul><ul><li>What is natural selection? </li></ul><ul><li>What are the 5 steps of evolution? </li></ul><ul><li>What is convergent evolution and how does it relate to analogous structures? </li></ul><ul><li>What are the three structures discussed in comparative anatomy? </li></ul>
  3. 3. Natural Selection in Depth <ul><li>SC.912.L.15.13 Describe the conditions required for natural selection, including: overproduction of offspring, inherited variation, and the struggle to survive, which result in differential reproductive success. </li></ul>
  4. 4. <ul><li>What is the difference between artificial and natural selection? </li></ul>
  5. 5. Artificial Selection <ul><li>Cattle and Livestock </li></ul><ul><li>Ranchers usually only breed their best cattle…. Why? </li></ul>
  6. 6. Natural Selection <ul><li>What is natural selection? </li></ul><ul><ul><li>When an adaptation/characteristic allows one organism to survive and reproduce better than others </li></ul></ul>
  7. 7. What’s required for natural selection? <ul><li>REPRODUCTION!!! </li></ul><ul><li>Overproduction of offspring: Animals reproduce to create more offspring than will likely survive (ex. Insects, birds, mice, fish, frogs, etc. etc.) </li></ul><ul><li>Remember the term “population capacity” </li></ul>
  8. 8. Struggle to Survive <ul><li>If resources were unlimited and there was no threat from predation, there would be less natural selection. </li></ul><ul><li>The struggle to survive results in one organism “besting” another in the competition for resources </li></ul><ul><ul><li>That takes care of the “Survival of the Fittest”… but remember, natural selection is not just about survival… </li></ul></ul>
  9. 9. Differential Reproductive Success <ul><li>If one organism survives extremely well but never actually reproduces, its genes will never be passed down and cannot be selected for… </li></ul><ul><ul><li>Evolutionary “fitness” is the ability of an organism to survive and reproduce… it’s all about passing on your genes… </li></ul></ul>
  10. 10. Adaptations that aid in reproduction <ul><li>The goal of reproduction is how you end up with sometimes unusual and frivolous looking adaptations…. </li></ul>
  11. 11. Inherited Variation <ul><li>There must be genetic variation in the population. </li></ul><ul><li>If there is no genetic variation, then the genes coding for certain traits will always be the same. </li></ul><ul><li>Genes are passed down from generation to generation, thus, we get heritable traits . </li></ul><ul><li>What are some traits/characteristics that are NOT heritable? </li></ul>
  12. 12. CFU <ul><li>Why is important to have inherited, genetic variation? </li></ul><ul><li>What are some factors of life that contribute to the “struggle to survive” </li></ul><ul><li>Natural selection is an adaptation that helps a species survive and WHAT?! </li></ul><ul><li>Explain population capacity </li></ul><ul><li>Define being evolutionary fit </li></ul>
  13. 13. BIODIVERSITY <ul><li>SC.912.L.15.3 Describe how biological diversity is increased by the origin of new species and how it is decreased by the natural process of extinction. </li></ul>
  14. 14. BIOLOGICAL DIVERSITY <ul><li>First… what is it? </li></ul><ul><ul><li>Biological diversity refers specifically to the variety of organisms within a given area </li></ul></ul><ul><li>Next… why are we concerned with it? </li></ul><ul><ul><li>One of the ways in which scientists evaluate the environmental health of a region </li></ul></ul>
  15. 15. Reduction of Diversity <ul><li>Reduction of diversity creates less opportunities for inherited variation </li></ul><ul><ul><li>Why does that matter? </li></ul></ul>
  16. 16. Biodiversity can be reduced by… <ul><li>#1 Loss of Habitat (ex. Rainforest) </li></ul>
  17. 17. <ul><li>#2 Decrease in Range (ex. Western ranching) </li></ul>
  18. 18. <ul><li>#3 Introduction of non-native species (ex. Dodo Bird, Rats, Mongoose) </li></ul><ul><ul><li>This usually happens by accident, such as stowaways in ship and aircraft cargo holds </li></ul></ul><ul><ul><li>Can be devastating </li></ul></ul><ul><ul><li>Management of this issue must be thoroughly thought through </li></ul></ul>
  19. 19. <ul><li>The Dodo lived on the island Mauritius and was made extinct by invasive dogs, pigs, rats, etc. as well as some initial human hunting. </li></ul>
  20. 20. <ul><li>Mongoose were purposefully introduced to Hawaii to deal with the rat problem (also an invasive species)… but now, due to differences in their sleeping patterns, they both live there! </li></ul>
  21. 21. <ul><li>#4 Over hunting-fishing-poaching (ex. Passenger Pigeon, Tasmanian Tiger/Wolf) </li></ul>
  22. 22. Genetic Diversity <ul><li>Loss of inherited variation </li></ul><ul><li>When a species on the brink of extinction is preserved, reduced genetic diversity within the species is a concern </li></ul><ul><ul><li>Why? </li></ul></ul><ul><li>Populations that survive extinction tend to be genetically uniform </li></ul>
  23. 23. The result… <ul><li>Genetic uniformity is detrimental </li></ul><ul><ul><li>If one individual is susceptible to disease all individuals are susceptible disease </li></ul></ul><ul><ul><li>If one individual has a weakness, they all have the same weakness </li></ul></ul><ul><ul><ul><li>Easy to wipe out a whole population </li></ul></ul></ul><ul><li>High genetic variation means at least some individuals will survive changes or diseases and the species will avoid extinction </li></ul>
  24. 24. BIOLOGICAL DIVERSITY = STABILITY <ul><li>As each species goes extinct, the system becomes more unstable. </li></ul><ul><li>Stable ecosystems are more flexible and can rebound from natural disturbances and disasters. </li></ul><ul><li>Unstable ecosystems are susceptible to total collapse! This would lead to mass extinctions! </li></ul>
  25. 25. Once its gone its gone forever <ul><li>Mutations are the only things that increase genetic variation </li></ul><ul><li>Since that evolution takes millions of years it is pretty much safe to say that once genetic diversity is gone its lost forever </li></ul><ul><ul><li>Chances are it will not come back the same </li></ul></ul><ul><ul><li>Why not? </li></ul></ul>
  26. 26. So…. In Essence <ul><li>When new species evolve, biodiversity is increased. </li></ul><ul><ul><li>An increase in biodiversity leads to greater ecological stability </li></ul></ul><ul><li>When a species goes extinct, biodiversity is decreased </li></ul><ul><ul><li>A decrease in biodiversity leads to ecological INstability </li></ul></ul>
  27. 27. Extinction <ul><li>Extinction: What is it? </li></ul><ul><li>What’s the difference between threatened, endangered, and extinct? </li></ul><ul><ul><li>Extinct: species that no longer exist </li></ul></ul><ul><ul><li>Endangered: species that are in immediate danger of becoming extinct </li></ul></ul><ul><ul><li>Threatened: species in danger of becoming endangered in the near future </li></ul></ul>
  28. 28. WE CAN DO SOMETHING! <ul><li>There is at least one issue that you and I can do something about preserving biological diversity… </li></ul>