Natural & Artificial Selection - PowerPoint PPT Presentation

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Natural & Artificial Selection

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  1. Natural and artificial selection

  2. Natural selection • Natural selection is a mechanism for evolution. Those organisms best adapted to their environment are more likely to survive to reproductive age and pass on alleles for favourable characteristics to their offspring. In this case, the environment (nature) is doing the selecting.

  3. Artificial selection • For around 10,000 years, animals and plants have been artificially selected. In artificial selection: • humans select the organisms with useful characteristics • humans allow those with useful characteristics to breed and prevent the ones without the characteristics from breeding • thus, humans have a significant effect upon the evolution of these populations or species

  4. The genetic processes underlying both natural and artificial selection are the same.

  5. Artificial selection in dairy cows

  6. Artificial selection in dairy cows

  7. Artificial selection in dairy cows

  8. Artificial selection in bread wheat

  9. Artificial selection in bread wheat

  10. Artificial selection in bread wheat

  11. Artificial selection in bread wheat

  12. Questions • Make a table to compare natural selection and artificial selection (include similarities as well as differences). • In the classification of T. aestivum and einkorn wheat, has the biological species concept or the cladistic concept been used? • The protein in wheat grains has a specific quality. When hydrated and kneaded it forms a sticky, rubbery mass that holds bubbles of gas produced from yeast, giving the characteristic light texture of bread. The only other cereal grain that produces a protein able to do this is rye. • Describe the nature and origin of the gas produced by yeast. • Explain why wheat flour used for bread-making needs to have a higher protein content than wheat flour used for making biscuits.