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biologyjunction/darwin%20&% 20natural%20selection%20notes%20bi.htm

Learn about the concept of variation, the influence of Lamarck and Darwin, and the theory of natural selection as explained by Charles Darwin. Understand how adaptations and fitness lead to the evolution of populations over time.

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biologyjunction/darwin%20&% 20natural%20selection%20notes%20bi.htm

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  1. http://www.biologyjunction.com/darwin%20&%20natural%20selection%20notes%20bi.htmhttp://www.biologyjunction.com/darwin%20&%20natural%20selection%20notes%20bi.htm • https://www.biologycorner.com/lesson-plans/evolution-taxonomy/evolution-notes/

  2. Variation • What is variation? Examples. • How do we get variation? • Can everybody have the same types of variation?Explain. • Gene pool – set of genes available in a population

  3. Jean Baptiste de Lamarck • Use and Disuse • Inheritance of Acquired Characteristics • Organisms acquire traits and pass these traits to offspring

  4. Lamarck’s Influence Incorrect • Not all traits acquired get passed on Important • Introduced change over time • Realized organisms are changing

  5. Charles Darwin • Naturalist • Traveled on the HMS Beagle (1831-1836) • South America, Galapagos Islands, Australia • Wrote The Origin of Species

  6. Galapagos Islands • Volcanic islands off the South American coast • no land mammals or amphibians • Island species varied from the mainland species, and from island-to-island • Each island had either long or short necked tortoises depending on the island’s vegetation

  7. Finches • Finches on the Galapagos Islands resembled a mainland finch, but there were more types • Bill shapes are adaptations to different means of gathering food. • Galapagos finch species varied by nesting site, beak size, and eating habits

  8. People influenced Darwin • Charles Lyell • Malthus • populations can grow exponentially • the are limited by war, disease, or resources • This led to Darwin’s idea that there’s a struggle for existence

  9. Darwin’s Theory • Humans can breed for certain traits • Dogs • Domestic plants • Could also happen in nature • Over time this could produce new species

  10. Darwin’s Theory • adaptation - trait that helps an organism be more suited to its environment • adaptations develop over time • constant struggle for existence • Natural selection – organisms best suited for the environment reproduce more successfully • Survival of the fittest • Also proposed by Alfred Russell Wallace • Over several generations organisms with favorable traits increase

  11. 1. Variation within a population 2. Variations are passed on

  12. 3. More offspring are produced than can survive 4. Organisms that survive have favorable variations (adaptations)

  13. Modification by Natural Selection • Fitness – genetic contribution to next generation • Environment “selects” traits • Favorable traits depend on demands of env’t Reproduce more Greater fitness Better adapted

  14. Summary of Darwin • Natural Selection – organisms best adapted to the environment survive and reproduce • the population is the unit of evolution • individuals do not evolve during their lifetimes • Conclusion on Finches • ancestral group of finches colonized islands • Absence of competitors allowed finches to gradually become specialized

  15. What is natural selection? Agenda for Friday May 27th • Finish notes • Breeding bunnies lab • Theories coloring

  16. Cheetahs are able to run faster than 60 miles per hour when chasing prey. How would a biologist explain how the ability to run fast evolved in cheetahs, assuming their ancestors could run only 20 mph?

  17. A long time ago, some cheetahs were faster than the others • The cheetahs that could run faster were able to catch their prey and were better able to survive • The slow cheetahs died off, or weren’t able to reproduce as successfully • The cheetahs that survived were the ones that could run faster

  18. How does gene pool relate to variation? Agenda for Wednesday May 21st • Finish theories notes

  19. How did the heavy coat in polar bears evolve if their ancestors had thinner coats? 1. A long time ago, some polar bears had thicker fur than others 2. The thicker coat was favorable 3. The polar bears with thin coats died off. 4. The ones with thicker coats survived and reproduced.

  20. Peppered Moths

  21. Theory of Evolution • Evolution – change in the inherited traits of a population of organisms over time • NOT new species arising from pre-existing species

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