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Lamarck

The History of Evolution. Darwin. Lamarck. Cuvier. Evolution. Defined: the process of biological change by which descendants come to differ from their ancestors. 5 factors that lead to evolution: Genetic drift Gene flow Mutations Sexual selection Natural Selection.

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Lamarck

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  1. The History of Evolution Darwin Lamarck Cuvier

  2. Evolution • Defined: the process of biological change by which descendants come to differ from their ancestors. • 5 factors that lead to evolution: • Genetic drift • Gene flow • Mutations • Sexual selection • Natural Selection We’ll talk more about these later.

  3. lion Species • Species: group of organisms that can interbreed and produce fertile offspring • Different species rarely breed • Interspecies (between different species) breeding often results in sterile offspring • Ex: Horse x Donkey = Mule • Ex: Lion x Tiger = Liger tiger liger

  4. horse donkey mule

  5. Jean Baptiste de Lamarck • Acquired Inheritance: Early theory where organisms could acquire and pass traits after birth. • Cause: environmental changes forced individuals to change • Problem: Traits acquired after fertilization cannot be passed to offspring • Early Belief: Giraffes & Long Necks • Long necks are result of stretching to reach leaves • Extra length was passed on to offspring

  6. Geologic Change • Early belief: • Earth ~6,000 years old • Life remained unchanged • “New” Observations • Rock layers (strata) contained differing fossils • Deeper fossils (older) less complex • Environmental changes thought to affect life characteristics

  7. Charles Darwin • Observed: • Organisms have variations based upon environment • Similarities between extinct fossils & modern life • Marine fossils atop mountains • Natural Selection: Process where organisms with favorable traits survive and reproduce • Major concept in biology published in The Origin of Species (1859)

  8. Finches are another example. • Finches with strong, thick beaks live in areas with a lot of large, hard shell nuts. • Finches with delicate beaks live in areas where small insects and fruits are readily available.

  9. Variation: Inherited traits that make an individual different from others Green, flat wings of the insect above Adaptation: Variation increases the chance of survival Ability to blend with environment Adaptation & Variation

  10. Butterflies won't lay eggs on plants with fake egg spots

  11. Can you find the geckos?

  12. Gross....bird poop...or is it???

  13. Causes of Genetic Variation • Genetic variation increases chances some organisms survive in changing environments • Gene Pool: All alleles within a population • Two main causes of genetic variation: 1) Mutations: Random genetic changes may affect phenotypes 2) Recombination: During meiosis, genes recombine in varying patterns

  14. Variation: 4 Different Gametes Chromatids copied Crossing- over Crossing- Over finished Genetic variation! Four differing chromatids

  15. Quick Review • Features of a species can evolve, or change over time • Natural selection is when favorable traits allow survival & reproduction • Variations allow an organism to be better suited to its environment

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