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Lamarck vs. Darwin

Lamarck vs. Darwin. Intro to change in organisms. What is a theory?. Theory = the most probable explanation for a large set of data based on the best available evidence Theories are used to make predictions about new data. What was LaMarck’s Theory?. Jean Baptiste LaMarck: 1800’s Believed:

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Lamarck vs. Darwin

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  1. Lamarck vs. Darwin Intro to change in organisms

  2. What is a theory? • Theory = the most probable explanation for a large set of data based on the best available evidence • Theories are used to make predictions about new data

  3. What was LaMarck’s Theory? • Jean Baptiste LaMarck: 1800’s • Believed: • Change Occurs Over Time • inheritance of acquired characteristics • acquired changes were passed to offspring • Law of Use and Disuse • If a body part were used, it got stronger • If body part NOT used, it deteriorated • Examples: Body builders or pierced ears

  4. Lamarck’s Theory of Evolution • More examples: • Pierced ears • Blacksmiths & Their Sons (muscular arms) • Giraffe’s Necks Longer from stretching)

  5. Lamarck’s Theory of Evolution • More examples • Traits Acquired During Ones Lifetime Would Be Passed To Offspring Clipped ears and tails of dogs could be passed to offspring!

  6. What were Lamarck’s Mistakes? • Was he correct?? • NO! • Traits are passed down from one generation to the next by genes, not by an individual’s life experiences or activities • Lamarck did NOT know how traits were inherited (Traits are passed through genes) • Genes Are NOT Changed By Activities In Life • Change Through Mutation Occurs Before An Organism Is Born

  7. Where did the HMS Beagle go? Charles Darwin • Born Feb. 12, 1809 • Joined Crew of HMS Beagle, 1831 • Naturalist • 5 Year Voyage around world • Astounded By Variety of Life

  8. Voyage of the Beagle During His Travels, Darwin Made Numerous Observations And Collected Evidence That Led Him To Propose A Revolutionary Hypothesis About The Way Life Changes Over Time

  9. What were Darwin’s Belief’s? • Survival of the fittest OR natural selection • Food and resources are limited • So organisms have to fight to get them (lions fight for food, etc) • Too many organisms, they will fight to survive • not all offspring will survive

  10. What happened to the giraffe’s? • Survival of the fittest or natural selection • Natural selection said the giraffes with short necks had less food to eat • Why? • the food resources changed to leaves only on the upper branches • What happened? • short necks could not reach upper branches and did not survive • Long neck giraffes survived because they were able to reach the food

  11. Evolution is the slow, gradual change in a population of organisms over time… a looooooooong time

  12. Where do we see this change? The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations “natural selection” New species evolve

  13. What is Natural Selection? • How does Selection occur? • Selection can occur from several factors: • Resource limitation • Predation • Industry (Environment) • Social influence (Society)

  14. Let’s look at a classic example of natural selection • Peppered moths!

  15. Peppered Moth-Evolution in Action • One such example is the evolution of the peppered moth Biston betularia. • British ecologist H. B. D. Kettlewell.

  16. Peppered Moth-Evolution in Action • The economic changes known as the industrial revolution began in the middle of the eighteenth century. • Since then, tons of soot have been deposited on the country side around industrial areas.

  17. Peppered Moth-Evolution in Action • The soot discolored and generally darkened the surfaces of trees and rocks. • In 1848, a dark-colored moth was first recorded.

  18. Peppered Moth-Evolution in Action • In 1950 man interceded again with the passage of smoke control laws in England and the land once again began to be green once again.

  19. Peppered Moth-Evolution in Action • During 1966- 1969, a survey of the town showed that of the 972 specimens collected, 25 were of the light speckled variety. • This is a clear indication that the peppered moth is again in the process of changing its color once again.

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