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Mechanism of Evolution

Mechanism of Evolution. Beth Walker Honors Biology. What is the mechanism for change over periods of time?. A. Jean Baptiste Lamarck – 1809 1. Organisms could acquire or lose certain traits during their lifetime based on their use or disuse of a body part/organ. 2. Lamarck Continued….

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Mechanism of Evolution

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  1. Mechanism of Evolution Beth Walker Honors Biology

  2. What is the mechanism for change over periods of time? A. Jean Baptiste Lamarck – 1809 1. Organisms could acquire or lose certain traits during their lifetime based on their use or disuse of a body part/organ. 2.

  3. Lamarck Continued… 3. What are the problems with Lamarck’s hypotheses? a. An organism cannot alter its body parts due to effort alone. b. Traits inherited in an organism’s lifetime are not passed on to offspring through the sex cells/gametes.

  4. Lamarck – “Use and Disuse” Idea

  5. Thomas Malthus – 1798 1. If the human population continues to grow, unchecked, eventually habitat, food, and water could limit human population growth. 2. Darwin read Malthus’s work and applied it to plants and animals.

  6. Charles Darwin 1. First attended school to b/c a physician 2. Changes to b/c a clergyman 3. Hired as the naturalist on the ship, The Beagle, which sailed from 1831-1836 4. On the voyage, Darwin made copious notes and preserved specimens of organisms never seen in England.

  7. Charles Darwin Continued…

  8. Charles Darwin Continued… 5. Observed patterns suggesting that species change over time and give rise to new species 6. Mockingbirds, finches, & tortoises were slightly different on every island in the Galapagos chain of islands. 7. Hypothesized the idea of natural selection in 1838, but did not publish due to the reactions of the religious community. 8. Jointly published his idea of Natural Selection (On the Origin of the Species) in 1859, along with Alfred Russell Wallace, which states:

  9. Charles Darwin Continued … • Lead to the ideas of Natural Selection & Descent with Modification

  10. Natural Selection - Microevolution a. There is a tendency for overpopulation b. Organisms with beneficial traits live longer and reproduce more. c. The beneficial genes for the environment are passed on to offspring during reproduction. • Camouflage – blending into environment • Mimicry – copying the appearance of another

  11. Descent with Modification - Speciation a. Natural selection produces organisms that have different structures or occupy different habitats. b. Over time, each new species is descended, with changes, from other species over time.

  12. What is the raw material for natural selection? A. Genetic Variation – differences in the DNA b/w organisms of the same species B. What leads to genetic variation? 1. Genetic Recombination  crossing over in Prophase I of meiosis 2. Mutations  random changes in DNA; can be beneficial or detrimental

  13. Types of Natural Selection A. Directional Selection  individuals at one end of a curve have a higher fitness than other individuals.

  14. Types of Natural Selection B. Stabilizing Selection  individuals near the center of the curve have the highest fitness.

  15. Types of Natural Selection C. Disruptive Selection  individuals at both extremes of a curve have the higher fitness.

  16. Types of Natural Selection

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