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Evolution by Natural Selection THE THEORY OF DARWIN

Evolution by Natural Selection THE THEORY OF DARWIN. mya. 1.5. Plants. Birds. 63. Mammals. 135. Reptiles. Seed Plants. Flowering. Amphibians. Insects. Dinosaurs. 180. Teleost Fish. Land Plants. Jawless Fish. 225. Chordates. Molluscs. Arthropods. 280. Multicellular Animals.

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Evolution by Natural Selection THE THEORY OF DARWIN

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  1. Evolutionby Natural Selection THE THEORY OF DARWIN

  2. mya 1.5 Plants Birds 63 Mammals 135 Reptiles Seed Plants Flowering Amphibians Insects Dinosaurs 180 Teleost Fish Land Plants Jawless Fish 225 Chordates Molluscs Arthropods 280 Multicellular Animals Green Algae 350 Photosynthetic Bacteria Anaerobic Bacteria 400 430 500 570 700 4500 Life’s Natural History is a record of Successions & Extinctions

  3. LaMarck • 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

  4. Charles Darwin • 1809-1882 • British naturalist • Proposed the idea of evolution by natural selection • Collected clear evidence to support his ideas

  5. Voyage of the HMS Beagle • Invited to travel around the world • 1831-1836 (22 years old!) • makes many observations of nature • main mission of the Beagle was to chart South American coastline Robert Fitzroy

  6. Voyage of the HMS Beagle • Stopped in Galapagos Islands • 500 miles off coast of Ecuador

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

  8. Finch? Sparrow? Warbler? Woodpecker? 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?

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

  10. Darwin’s finches • Differences in beaks • associated with eating different foods • survival & reproduction of beneficial adaptations to foods available on islands Warbler finch Cactus finch Woodpecker finch Sharp-beaked finch Small insectivorous tree finch Small ground finch Warbler finch Large insectivorous tree finch Cactus eater Mediumground finch Tree finches Ground finches Insect eaters Seed eaters Vegetarian tree finch Large ground finch Bud eater

  11. Darwin’s finches • Darwin’s conclusions • small populations of original South American finches landed on islands • variation in beaks enabled individuals to gather food successfully in the different environments • over many generations, the populations of finches changed anatomically & behaviorally • accumulation of advantageous traits in population • emergence of different species

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

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

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

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

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

  17. 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

  18. Voyage: 1831-1836 “On the Origin of Species by Means of Natural Selection” November 24, 1859, Darwin published

  19. Essence of Darwin’s ideas • 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

  20. 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

  21. Stick your neck out…Ask Questions!

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