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Natural Selection

Natural Selection. A Mechanism for Evolutionary Change. Evolution. Change in the genes of a population over time. Evidence: includes fossil record, DNA and protein studies and direct observation. indicates that living things on the earth change over time.

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Natural Selection

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  1. Natural Selection A Mechanism for Evolutionary Change

  2. Evolution Change in the genes of a population over time. Evidence: • includes fossil record, DNA and protein studies and direct observation. • indicates that living things on the earth change over time. • Example – Increasing bacterial resistance to antibiotics. We have directly observed this change.

  3. Charles Darwin • Natural selection is the cause evolutionary change. • AKA “survival of the fittest”

  4. Natural Selection (4 points) • Genetic variation (differences) exists in all populations. • Some variations are favorable • Not all young produced in each generation can survive • Individuals with favorable variations have a greater chance of reproducing and passing on their variations (genes/traits).

  5. Which variation is favorable? What will the next generations look like? • w

  6. Gypsy Moths

  7. Gypsy Moths

  8. Gypsy Moths in England • Factories spewed out massive amounts of air pollutants. • With the change in the environment the tree trunks were darker in color. • Moths with dark coloration (camouflage) survived to reproduce…passing on their genes for dark color to next generation. • This change in the genes of the population over time = evolution.

  9. How do the Peacock’s large brightly colored feathers help it survive? • Do you think these feathers help it evade predators or find food? • Obviously not!

  10. What does “survival of the fittest” really mean? • The fittest member of a population is the individual that produces the most offspring…passes on the most copies of its genes.

  11. Selective Pressures • Factors that result in selection of specific variations/phenotype: • Predation • Changes in climate or other environmental factors • Disease • Competition for food, space, reproductive resources…survival means passing on genes.

  12. So why the funky feathers? Do they help it fly faster?

  13. The feathers help the peacock attract a mate and thus, pass on its genes. Survival fittest…not necessarily the strongest/fastest…

  14. Why/how did the giraffe get such a long neck? • Explain this using what you have learned about natural selection ( the 4 points).

  15. Adaptations • Characteristics that help an organism to survive and reproduce. • Are the results of evolution by natural selection • Giraffe… neck • Peacock… flamboyant feathers • Bacteria… resistance to antibiotics • Human…?

  16. Mutations • Mutations are random changes in the DNA (genes) of an organism. • Most mutations are unfavorable… occasionally, they may be beneficial and lead to evolutionary changes.

  17. Would this mutation make you more fit?

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