1 / 40

Ch. 17

Ch. 17. Evidence of Evolution. Laws vs. theories. Laws—formed by repetitive observations or conclusions Ex: law of falling objects Theory—explains why objects do what they do Ex: gravity. EVOLUTION & NATURAL SELECTION.

eric-perry
Download Presentation

Ch. 17

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ch. 17 Evidence of Evolution

  2. Laws vs. theories • Laws—formed by repetitive observations or conclusions • Ex: law of falling objects • Theory—explains why objects do what they do • Ex: gravity

  3. EVOLUTION & NATURAL SELECTION • Evolution—biological changes in the genetic makeup of an organism over a period of time which could cause changes in the phenotype of a population; we OBSERVE things changing • Natural Selection—the tendency of an organism to adapt to its environment (may lead to genetic changes) in order to survive AND reproduce

  4. Selective Breeding & Evolution • Evolution is genetic change in a line of descent through successive generations • Selective breeding practices yield evidence that heritable changes do occur

  5. Results of Artificial Selection • Extremes in size • Great Dane and Chihuahua • Extremes in form • Short-legged dachshunds • English bulldog • Short snout and compressed face • Extreme traits lead to health problems

  6. Domestication of Dogs • Began about 50,000 years ago • 14,000 years ago - artificial selection • Dogs with desired forms of traits were bred • Modern breeds are the result

  7. Early Scientific Theories • Hippocrates - All aspects of nature can be traced to their underlying causes • Aristotle - Each organism is distinct from all the rest and nature is a continuum or organization

  8. Biogeography • Size of the known world expanded enormously in the 15th century • Discovery of new organisms in previously unknown places could not be explained by once accepted beliefs by Aristotle, Hippocrates, etc.

  9. Biogeography Fig. 17-3a, p.262

  10. Biogeography Fig. 17-3b, p.262

  11. Biogeography Fig. 17-3c, p.262

  12. Darwin GalapagosIslands Wolf Pinta Volcanic islands far off coast of Ecuador All inhabitants are descended from species that arrived on islands from elsewhere Marchena Genovesa Santiago EQUATOR Bartolome Seymour Rabida Blatra Pinzon Fernandina Santa Cruz Santa Fe Tortuga San Cristobal Isabela Espanola Floreana Fig. 17-6d, p.265

  13. Galapagos Finches • Darwin observed finches with a variety of lifestyles and body forms • On his return, he learned that there were 13 species • He attempted to correlate variations in their traits with environmental challenges

  14. Malthus - Struggle to Survive • Thomas Malthus, a clergyman and economist, wrote essay that Darwin read on his return to England • Argued that as population size increases, resources dwindle, the struggle to live intensifies, and conflict increases

  15. Darwin’s Theory A population can change over time when individuals differ in one or more heritable traits that are responsible for differences in the ability to survive and reproduce.

  16. Natural Selection • A difference in the survival and reproductive success of different phenotypes • Acts directly on phenotypes and indirectly on genotypes

  17. Variation in Populations • All individuals have the same genes that specify the same assortment of traits • Most genes occur in different forms (alleles) that produce different phenotypes • Some phenotypes compete better than others

  18. Variation in Populations • All individuals have the same genes that specify the same assortment of traits • Most genes occur in different forms (alleles) that produce different phenotypes • Some phenotypes compete better than others

  19. Geological Discoveries • Similar rock layers throughout world • Certain layers contain fossils • Deeper layers contain simpler fossils than shallow layers • Some fossils seem to be related to known species

  20. Stratification • Fossils are found in sedimentary rock • This type of rock is formed in layers • In general, layers closest to the top were formed most recently

  21. Stratification Fig. 17-11, p.269

  22. Fossilization • Organism becomes buried in ash or sediments • Organic remains become infused with metal and mineral ions • Carbon 14 dating Fig.19.6, p. 309

  23. Radiometric Dating parent isotope in newly formed rock after one half-life after two half-lives a A simple way to think about the decay of a radioisotope to a more stable form, as plotted against time. Fig. 17-12a, p.270

  24. Fig. 17-13, p.271

  25. Continental Drift • Idea that the continents were once joined and have since “drifted” apart • Initially based on the shapes • Wegener refined the hypothesis and named the theoretical supercontinent Pangea

  26. Comparative Morphology • Study of similarities and differences in body plans of major groups • Puzzling patterns: • Animals as different as whales and bats have similar bones in forelimbs • Some parts seem to have no function

  27. Comparative Morphology • Comparing body forms and structures of major lineages • Guiding principle: • When it comes to introducing change in morphology, evolution tends to follow the path of least resistance

  28. Morphological Divergence • Change from body form of a common ancestor • Produces homologous structures Fig. 17-17, p.274

  29. Morphological Divergence 1 2 c chicken 3 Fig. 17-17c, p.274

  30. Morphological Divergence 1 4 5 2 3 e Porpoise Fig. 17-17e, p.274

  31. Morphological Divergence 1 2 3 4 5 g Human Fig. 17-17g, p.274

  32. Morphological Convergence • Individuals of different lineages evolve in similar ways under similar environmental pressures • Produces analogous structures that serve similar functions

  33. Morphological Convergence Fig. 17-18a, p.275

  34. Morphological Convergence Fig. 17-18b2, p.275

  35. Comparative Development • Each animal or plant proceeds through a series of changes in form • Similarities in these stages may be clues to evolutionary relationships • Mutations that disrupt a key stage of development are selected against

  36. Similar Vertebrate Embryos Aortic arches Adult shark Early human embryo Two-chambered heart Certain veins

  37. Comparative Biochemistry • Kinds and numbers of biochemical traits that species share is a clue to how closely they are related • Can compare DNA, RNA, or proteins • More similarity means species are more closely related

  38. Comparative Biochemistry p.278

  39. Nucleic Acid Comparison • Use single-stranded DNA or RNA • Hybrid molecules are created, then heated • The more heat required to break hybrid, the more closely related the species

  40. Comparing Proteins • Compare amino acid sequence of proteins produced by the same gene • Human cytochrome c (a protein) • Identical amino acids in chimpanzee protein • Chicken protein differs by 18 amino acids • Yeast protein differs by 56

More Related