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Evolution

Evolution. TIME. 13-1 Evolution and Life’s Diversity. Evolution is a theory, like many other scientific theories Scientists have accumulated significant evidence that modern organisms were produced by change over time.

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Evolution

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  1. Evolution TIME

  2. 13-1 Evolution and Life’s Diversity • Evolution is a theory, like many other scientific theories • Scientists have accumulated significant evidence that modern organisms were produced by change over time.

  3. Evolution: the process by which a species changes over time resulting from environmental pressure.

  4. Who was Darwin? • Lived 1809-1882 • Well educated in biology and natural history • Traveled the world by sea • The plant and animal life he saw on many of the remote islands he visited, peaked his curiosity.

  5. Darwin: “Why is it that way?” • famous for the theory of Natural Selection: • Survival and reproduction by individual organisms based on their respective fitness in changing environments. • “Survival of the Fittest”

  6. Diversity of Life • Diversity – a variety of living things • Estimates for # of species on Earth range from 3 to 20 million. • More than 99.9% of the species that have inhabited Earth are now extinct.

  7. What is Fitness? • Fitness- An organism’s ability to survive and reproduce in a given environment based on its physical traits and behaviors. • An organism with favorable traits and behaviors is more likely to survive, and pass those traits on to subsequent generations

  8. Principle of Common Descent • Darwin’s theory that species have shared or common ancestors. • Just as each individual organisms comes from previous organisms, each species has developed from previous species.

  9. Adaptation • Adaptation: any inherited characteristic that allows an individual to better survive and reproduce in a given environment • Tiger’s camouflage stripes • Polar bear’s thick fur and fat • Eagle’s talons and beak

  10. Evidence in Living Organisms • Similarities in Early Development • Embryology • Similarities in Body Structure • Homologous Structures • Similarities in Biochemistry

  11. Early Development • Embryology- study of organisms at early stages of development • Vertebrates (for example) show significant similarities during early development

  12. Which one is human?

  13. Which one is human?

  14. Body Structures • Homologous Structures - structures that develop from the same body parts Ex: Human arm, dolphin fin, bat wing, bird wing….

  15. Analogous Structures - Structures that are not homologous, but serve similar purposes: • Ex: trachea tubes vs lungs • Ex: bird wings vs dragonfly wings

  16. Vestigial Structures - organs or structures that serve no purpose • wisdom teeth, appendix, snake legs • whale pelvis

  17. Biochemistry • DNA/RNA structure identical throughout all organisms • ATP found in all living systems • Complex proteins (cytochrome c) • Closely related organisms have almost identical biochemistry

  18. 6.5 Evolution How Change Occurs

  19. 14-1 Evolutionary Theory • A collection of carefully reasoned and tested hypotheses about how evolutionary change occurs.

  20. Early Explanationsof Evolutionary Change • Lamarck (1744-1829) • Natural urge to better themselves • Use and disuse • Passing on acquired traits

  21. Shaping Darwin’s Thinking: • Charles Lyell- Understood that Earth was very old.

  22. Shaping Darwin’s Thinking • Malthus- Babies are being born faster than people are dying. • Population must be limited • Darwin realized that plant and animal populations must be controlled against growth.

  23. 14-2 Evolution by Natural Selection • Natural Selection- Survival and reproduction by individual organisms based on their respective fitness in changing environments.

  24. 14-2 Evolution by Natural Selection Four Main Parts 1. Overpopulation- more individuals born than can survive

  25. 2. Variation- Each individual is genetically different. 3. Competition- Individuals compete for resources: Food, water, space, mates “Survival of the fittest”

  26. Natural selection- Individual with best traits (adaptations) to the environment will survive and reproduce.

  27. Kettlewell and the Peppered Moths

  28. Kettlewell and the Peppered Moths

  29. 14-3 Genetics and Evolution Evolution happens through changes in genes The environment dictates which adaptations (phenotypes) are favorable.

  30. An individual’s phenotype is controlled by it’s genes (genotype) The total amount of genes found in a population is the GENE POOL

  31. Changes in the Gene Pool can cause the population to evolve Changes in the gene pool are caused in many ways

  32. Causes of Change 1. Mutations in the genes (DNA) of individuals allowing new adaptations 2. Geographic Isolation- population is split by some physical barrier: river, mountain, ocean

  33. 3. Reproductive Isolation: individuals unable to breed together: behavior or physical characteristics 4. Temporal Isolation: changes in mating cycles

  34. The formation of a new species from a preexisting population is SPECIATION.

  35. Some species evolve to new environments with new adaptations- divergent evolution

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