Artificial selection

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this is a compilation of a few different slide shows available around the internet along with some of my own slides

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Artificial selection

  1. 1. Artificial selectionandNatural selection<br />
  2. 2. Darwin’s Theory<br />The millions of species that exist were not created separately, but have resulted from modifications to one or a few primitive species over time.<br />This is known as DESCENT WITH MODIFICATION<br />The mechanism for this process is NATURAL SELECTION<br />
  3. 3. <br />Darwin used his observations of man’s success in breeding different types of animals and plants as inspiration for his idea of NATURAL SELECTION<br />To help explain his ideas he used the term ARTIFICIAL SELECTION to refer to trait selections made by man.<br />He used his observation as an analogy to help explain natural selection.<br />
  4. 4. Darwin gave examples of different “selective breeding” in agriculture and with other domesticated animals<br />One of the examples Darwin used to show how variations in individuals within a population can be selected by humans to “create” different breeds was pigeons.<br />
  5. 5.
  6. 6. Dogs<br />Dogs are another example of man’s success in selecting for various traits to produce different breeds.<br />
  7. 7. Dogs – bred for a purpose<br />Dogs have been selectively bred for a purpose for 15,000 years<br />Starting with some wolves, dogs were initially bred to help with:<br />hunting; producing hounds, terriers, and retrievers<br />farming; producing herding dogs and guard dogs<br />Modern breeding has given us companion dogs and toy dogs – whose purpose is to keep us company… funnily enough<br />
  8. 8. PBS video segment – “Dogs that changed the world”<br />Podcast – “breeders” from 2005 Holiday Lectures on Science by Howard Hughes Medical Institute BioInteractive.<br />
  9. 9. Dogs bred as sighthounds - clockwise from top left: Whippet, Borzoi, and Saluki<br />Can you see the similarities in their anatomy?<br />What physical characteristics do you think were selected?<br />
  10. 10. Dogs bred as herding dogs – clockwise from top left – Border collie, Lancashire heeler, Rottweiler, Old English Sheepdog<br />Do you think the characteristics that are bred for are physical or behavioural?<br />Why?<br />
  11. 11. Dogs bred as companion dogs– clockwise from top right– Pomeranian, Teacup Chihuahua, Toy Poodle, Shih tzu, Pug<br />
  12. 12.  How do breeders do it? <br />Many species have been modified by breeders. This is the process:<br />The offspring of each generation vary. The differences may be so small that only an experienced breeder can detect them.<br />Those that are more like what the breeder wants are selected for further breeding; the rest aren’t allowed to breed<br />This is repeated<br />Eventually, the small differences add up to a large change in the breed.<br />Darwin calls this process ARTIFICIAL SELECTION<br />

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