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Darwin and Evolution by Natural Selection- Evidence

Darwin and Evolution by Natural Selection- Evidence. Raven Chapters 1 & 22. Science clearly favors critical inquiry. What was the doctrine of the time?. TINTORETTO The Creation of the Animals 1550. Evolution as Change Over Time. Evolution!. Early ideas of evolution!. Evolution!.

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Darwin and Evolution by Natural Selection- Evidence

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  1. Darwin andEvolutionby Natural Selection- Evidence Raven Chapters 1 & 22

  2. Science clearly favors critical inquiry What wasthe doctrineof the time? TINTORETTO The Creation of the Animals 1550

  3. Evolution as Change Over Time Evolution! Early ideas ofevolution! Evolution! Evolution! Evolution!

  4. LaMarck (1744-1829) • Organisms adapted to their environments by acquiring traits • change in their life time • Disuseorganisms lost parts because they did not use them — like the missing eyes & digestive system of the tapeworm • Perfection with Use & Needthe constant use of an organ leads that organ to increase in size — like the muscles of a blacksmith or the large ears of a night-flying bat • transmit acquired characteristics to next generation

  5. Lyell (1797-1875) • Geologist • Wrote- Principles of Geology • Outlined the story of ancient world of plants and animals in flux • Uniformitarianism • Economist • Wrote-Essay on the Principle of Population • Studies of human population limited by resources (Struggle for existance) • Malthusian catastrophe Malthus (1766-1834)

  6. Then along comes Darwin… Charles Darwin • 1809-1882 • British naturalist • Proposed the idea of evolution by natural selection • Collected clear evidence to support his ideas Galapagos Islands 1831-1836 22 years old!

  7. In historical context • Other people’s ideas paved the path for Darwin’s thinking competition: struggle for survivalpopulation growth exceeds food supply land masses change over immeasurable time

  8. Unique species

  9. Finch? Sparrow? Warbler? Woodpecker? Darwin found… birds Collected many different birds on the Galapagos Islands. Finch? Sparrow? Thought he found very different kinds… Warbler? Woodpecker?

  10. But Darwin found… a lot of finches Darwin was amazed to find out: All 14 species of birds were finches… But there is only one species of finch on the mainland! Large Ground Finch Small Ground Finch Finch? Sparrow? How didone species of finches becomeso many differentspecies now? Warbler Finch Veg. Tree Finch Warbler? Woodpecker?

  11. Correlation of species to food source Seedeaters Flowereaters Insecteaters Rapid speciation:new species filling new niches,because they inheritedsuccessfuladaptations. Adaptive radiation

  12. Beak variation in Galapagos finches (c) Seed eater. The large groundfinch (Geospiza magnirostris)has a large beak adapted forcracking seeds that fall fromplants to the ground. (a) Cactus eater. The long,sharp beak of the cactusground finch (Geospizascandens) helps it tearand eat cactus flowersand pulp. (b) Insect eater. The green warbler finch (Certhidea olivacea) uses itsnarrow, pointed beak to grasp insects.

  13. Darwin’s finches • Differences in beaks allowed some finches to… • successfully compete • successfully feed • successfully reproduce • pass successful traits onto their offspring

  14. More observations… Correlation of species to food source Whoa,Turtles, too!

  15. Many islands also show distinct local variations in tortoise morphology… …perhaps these are the first steps in the splitting of one speciesinto several?

  16. Moreobservations… Sloth fossils Glyptodont fossils Modern sloth Modern armadillos Why should extinct species & living speciesbe found on thesame continent?

  17. Artificial selection This is not just a process of the past… It is all around us today

  18. Selective breeding the raw genetic material (variation) is hidden there

  19. Selective breeding Hidden variation can be exposed through selection!

  20. A Reluctant Revolutionary • Returned to England in 1836 • wrote papers describing his collections & observations • long treatise on barnacles • draft of his theory of species formation in 1844 • instructed his wife to publish this essay upon his death • reluctant to publish but didn’t want ideas to die with him

  21. Alfred Russel Wallacea young naturalist working in the East Indies, had written a short paper with a new idea. He asked Darwin to evaluate his ideas and pass it along for publication. And then came the letter…. Then, in 1858, Darwin received a letter that changed everything…

  22. Your words have come true with a vengeance… I never saw a more striking coincidence…so all my originality, whatever it may amount to, will be smashed. To Lyell— The time was ripe for the idea!

  23. Voyage: 1831-1836 “On the Origin of Species by Means of Natural Selection” November 24, 1859, Darwin published http://www.pbs.org/wgbh/evolution/library/02/2/l_022_04.htl Darwin: Reluctant Rebel

  24. Essence of Darwin’s ideas • Evolution by Means of Natural Selection • variation exists in populations • over-production of offspring • more offspring than the environment can support • competition • for food, mates, nesting sites, escape predators • differential survival • successful traits = adaptations • differential reproduction • adaptations become more common in population

  25. LaMarckian vs. Darwinian view • LaMarck • in reaching higher vegetation giraffes stretch their necks & transmits the acquired longer neck to offspring • Darwin • giraffes born with longer necks survive better & leave more offspring who inherit their long necks

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