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  1. 1. EVOLUTION Theories on the Origin of Life
  2. 2. Extraterrestrial Origin This theory states that life originated on other Planets outside of our solar system, and was carried here on a meteorite or asteroid. 1. Intelligent life seeded the planet. 2. Organic molecules (1st bacterial cells) formed in space and were carried here by meteorites or asteroids.
  3. 3. Creationism Life was put here, on Earth, by divine forces. Because of the separation of church and state, we are not allowed to teach this in school. This is based on faith not fact. Relies on stories that have been passed down over the years.
  4. 4. Origin from Non-Living Matter Life arose from inanimate matter. Random events produced stable molecules that would reproduce themselves. Then Natural Selection favored changes that increased their rate of reproduction. This eventually lead to the first cell. Organic acids came together to form organisms.
  5. 5. Definition of Evolution Evolution is the process of change through time. It is the process by which modern organisms have descended from ancient organisms.
  6. 6. Evolutionary Theory Is the unifying principle for all the biological sciences. Provides an explanation for the differences in structure, function, and behavior among life forms. It includes the change in characteristics of populations through generations. Thus existing life forms have evolved from earlier life forms.
  7. 7. Supporting Evidence Comparative Anatomy- this is the comparative study of certain organisms showing similarities in anatomical features. Comparative Embryology- comparison of early embryonic development among groups of organisms reveals similarities which suggest common ancestry.
  8. 8. More Supporting Evidence Comparative Cytology- Organelles are structurally and functionally similar in most divergent organisms, suggesting that all living things are related to some degree. Comparative Biochemistry- Many different organisms have similar proteins and enzymes, therefore their DNA must be similar. Geologic Records- Fossils, the direct or indirect remains of organisms preserved in media, suggest links between modern and ancient forms, as well as, divergent pathways from common ancestors.
  9. 9. Origins of Life Early Theories on How Life Began: Spontaneous Generation and Scientific Experiments
  10. 10. Spontaneous Generation ABIOGENESIS- creation without life. Spontaneous Generation was the mistaken idea that life can arise from non-living materials. We now believe the cell theory. The cell theory states that all cells come from pre-existing cells. Ancient Egyptians believed that eels and frogs came from the mud of the Nile. Aristotle active principle responsible for life: fleas come from sweat mice come from garbage flies and maggots come from dead and decaying meat
  11. 11. Scientists and Experiments Jan Baptista van Helmont- He was a supporter of the belief in Spontanous Generation. He experimented with wheat grains in a sweaty shirt. After 21 days wheat grains are gone and mice are present. The active ingredient was sweat. Francisco Redi- (mid 1600s) discovered maggots came from flies not decaying meat. Questioning Spontaneous Generation. Anton Van Leeowenhoek- Was the first to use a microscope to see the first living cells. He called the small animals he observed animacules. Took pond water and boiled it. Then added hay. Organisms were found- hay was the active ingredient. John Needham- (1745) boiled flasks of broth, then sealed them. Days later microorganisms were found in the broth. Hypothesized that animacules came from the gravy.
  12. 12. Lorenzo Spallenzini- challenged Needham. Boiled contents longer, and left one flask open and the others closed. Life was found in the open flask, and not in the closed flask. This experiment supported Redis in that it proved life can only come from existing life. Louis Pasteur- took microorganisms/spores in the air and used flask with long curved necks to demonstrate that it was exposure to the air that allowed for the microorganisms to get into the broth in the flask This experiment took place over one year. This finally, and conclusively, disproved Spontaneous generation.
  13. 13. Primitive Life Forms Raw Materials- primitive Earth was very hot, consisting of inorganic substances in liquid, solid, and gaseous states, having a rich supply of energy. Matter- water condensing and falling as rain, carried the dissolved and atmospheric gases and minerals into the seas, forming a hot, thin, soup. Energy sources- in addition to heat energy in the form of lightening, solar radiation, and radioactive materials in the rocks, provided an energy rich environment.
  14. 14. Synthesis Energy from the environment contributed to the formation of chemical bonds among the dissolved particles of the hot, thin soup of the seas. What was formed by the chemical bonds? This type of synthesis led to the formation of organic molecules such as simple sugars, amino acids, and nucleic acids.
  15. 15. EARLY THEORIES OF EVOLUTION
  16. 16. Theories of Evolution Jean Baptiste Lamarck- 1809 French Biologist Proposed that life evolves or changes. Explained evolution as a process of adaptation. Law of Use and disuse. -New organs arise according to the needs of an organism, and their size is determined by the degree to which they are used. Inheritance of acquired characteristics.- Useful characteristics acquired by an individual during its lifetime can be passed on to its offspring. No evidence to support this theory.
  17. 17. Theories cont. August Weissman- Helped to disprove Lamarcks theory of Inheritance of Acquired Traits. Conducted experiments involving the removal of the tails of mice over several generations. Found that the offspring of the tail- less mice did not pass on that characteristic to their offspring.
  18. 18. Theories cont.. Hugo DeVries- Discovered mutations and proposed that it was these mutations that were the source of new traits that permitted evolution to occur. This was the one area, in Darwins theory, that was weak. Darwins theory did not account for the genetic basis for variations.
  19. 19. Charles Darwin- 19th century English Naturalist Proposed that evolution occurred as the result of Natural Selection. Overproduction- within a population more offspring are produced in each generation than can survive, because of limitations of space and food. Competition- individuals compete for the available food and opportunity to mate and reproduce. Variation- within each generation some individuals are better fitted to survive than others because of variations in characteristics. Survival of the Fittest- those individuals better fitted to survive are more likely to live long enough to reproduce. Transmission of Favorable Traits (Reproduction)- offspring of the fittest individuals will inherit the favorable variations that enabled their parents to survive and reproduce. Evolution of Species (Speciation)- accumulation of favorable variations will gradually lead to the appearance of new species better adapted to their environment. Weakness in Darwins Theory is that it does not account for genetic basis of variations. At the time, not much was known about the mechanisms of genetic inheritance.
  20. 20. Natural SelectionNatural Selection Natural selection is the process where inheritable traits that make it more likely for an organism to survive long enough to reproduce, become more common over successive generations of a population . It is a key mechanism of evolution. The Galapagos finches provide an excellent example of this process. Among the birds that ended up in arid environments, the ones with beaks better suited for eating cactus got more food. As a result, they were in better condition to mate. Similarly, those with beak shapes that were better suited to getting nectar from flowers or eating hard seeds in other environments were at an advantage there. In a very real sense, nature selected the best adapted varieties to survive and to reproduce. This process has come to be known as natural selection.
  21. 21. The Peppered Moth Study An Example of Natural Selection!
  22. 22. Write similarities and differences between these two organisms!
  23. 23. Both have the Scientific Name: Biston betularia Both are the same moth, commonly called peppered moths. There is a story behind these two different color variations. Click to find out what happened!
  24. 24. During the early 1800s in Birmingham, England there were dark and cream colored moths. However, almost all peppered moths were cream colored because the tree trunks were light colored. Can you find the moth on the tree trunk? Would it be an advantage or disadvantage for the moth to be light?
  25. 25. Industrial Revolution A greater number of factories were being created, which meant more pollution! WRITE: What do you think was happening to the peppered moths as a result of industrialism? Something was happening in the cities of England at this time, What could that have been?
  26. 26. WHATS HAPPENING! Around 1850, black- colored peppered moths started to become more common than cream, usually in heavily industrialized areas. Why did the frequency of black moths increase with the growing industries?
  27. 27. Darwins Theory of evolution by natural selection suggests a hypothesis.
  28. 28. White tree trunks were blackened by heavy pollution from factories. Which Moth is better adapted to its environment? Explain why?
  29. 29. Perhaps dark moths sitting on soot- darkened bark escaped being eaten by birds because it was too hard for the birds to see the dark moths against the dark background. Light-colored moths would have stood out against a dark background and woul