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Lamarck vs. Darwin

Lamarck vs. Darwin. Introduction to change in organisms. What is a theory?. The most probable explanation for a large set of data based on the best available evidence Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing.

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Lamarck vs. Darwin

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  1. Lamarck vs. Darwin Introduction to change in organisms

  2. What is a theory? • The most probable explanation for a large set of data based on the best available evidence • Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing

  3. What is a species?What is a population? • Species – group of a single type of organisms that interbreed and are reproductively isolated • White-tailed deer • Population – refers to a group of organisms of a particular species living in a certain area. • White-tailed deer on Mt. Nebo

  4. 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

  5. Lamarck’s Theory of Evolution • Giraffes all had SHORT necks originally • Giraffe’s Necks got LONGER from stretching for food • “Acquired” trait (long necks) then passed to offspring • Giraffe population became long-necked

  6. 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!

  7. 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

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

  9. 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

  10. Darwin’s Belief’s • Survival of the fittestORnatural selection • Food and resources are limited • So organisms have to COMPETE to get them (lions fight for food, space, mates …) • OVER PRODUCE too many organisms • Not all offspring will survive only the MOST FIT (not always the strongest!)

  11. 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 (couldn’t pass on genes) • Long neck giraffes survived & reproduced because they were able to reach the food

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

  13. Where do we see this change? • When there is an unequal ability of individuals to survive and reproduce … • This leads to a gradual change in a population with favorable characteristicsaccumulating over generations • Most fit “naturally” selected • New species evolves

  14. Natural Selection • How does Selection occur? • Selection of the most fit can occur from several factors: • Variations exist among individuals in a population • Competition for limited resources • Overpopulation • Predation/Disease

  15. Example of Natural Selection • A classic example of natural selection is the Peppered moths during Industrial Revolution in Europe

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