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CHAPTER 15 Tracing Evolutionary History

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  1. CHAPTER 15Tracing Evolutionary History Modules 15.1 – 15.5

  2. Are Birds Really Dinosaurs with Feathers? • Did birds evolve from dinosaurs? • Evolutionary biologists investigate this question by looking at the fossil record

  3. The fossil of the earliest known bird, Archeaopteryx, was discovered in 1861 • Fossils of dinosaurs with feathers may support the bird-dinosaur theory

  4. Divergent Evolution Similar species develop different adaptations to different environments

  5. Coevolution • Two or more species adapting to each other

  6. Rate of Evolution Slow and Steady or in Spurts? Gradualism– the idea that small changes build up slowly over time to produce large changes. Expectations – manyintermediate “missing link” fossils

  7. Punctuated Equilibrium The idea that populations go through periods of stability followed by short periods of rapid change. Expectations – fewer intermediate fossils

  8. EARTH HISTORY AND MACROEVOLUTION 15.1 The fossil record chronicles macroevolution • Macroevolution consists of the major changes in the history of life • The fossil record chronicles these changes, which have helped to devise the geologic time scale

  9. Figure 15.1

  10. Figure 15.1

  11. Figure 15.1

  12. Figure 15.1

  13. Figure 15.1

  14. Figure 15.1

  15. 15.2 The actual ages of rocks and fossils mark geologic time • The sequence of fossils in rock strata indicates the relative ages of different species • Radiometric dating can gauge the actual ages of fossils

  16. Dating How do scientists determine the relative age of a fossil? Stratification Radiometric dating

  17. Stratification The deeper strata (layers) were deposited first. Fossils found in lower layers are older than in higher layers.

  18. Radiometric Dating Isotopes – atoms with a different mass than usual Half life – the time required for half of the isotopes to decay. Carbon 14 – half life 5730 yrs Potassium 40 – half life 1.25 billion years

  19. C-14 isotope levels. Expect 100 g of C-14 in a fresh sample, A. Remains have 50 g. ½ of amount = one half-life 5,730 years old B. Remains have only 25 g ¼ of amount or ½ of ½ = 2 half-lives 11,460 years old C-14 Limited to about 50,000 years

  20. 15.3 Continental drift has played a major role in macroevolution • Continental drift is the slow, incessant movement of Earth’s crustal plates on the hot mantle EurasianPlate NorthAmericanPlate AfricanPlate PacificPlate Splitdeveloping NazcaPlate SouthAmericanPlate Indo-AustralianPlate Antarctic Plate Edge of one plate being pushed over edge of neighboring plate (zones of violent geologic events) Figure 15.3A

  21. Continental Drift

  22. CENOZOIC Eurasia North America Africa • This movement has influenced the distribution of organisms and greatly affected the history of life India SouthAmerica Australia • Continental mergers triggered extinctions • Separation of continents caused the isolation and diversification of organisms Antarctica Laurasia Millions of years ago MESOZOIC Gondwana Pangaea PALEOZOIC Figure 15.3B

  23. LungFish •,or.r_gc.r_pw.r_qf.&bvm=bv.42965579,d.b2I&fp=dcb7caf6882243e1&biw=1351&bih=652

  24. Lungfishes evolved when Pangaea was intact • Continental drift explains the distribution of lungfishes Figure 15.3C

  25. NORTHAMERICA ASIA EUROPE AFRICA SOUTHAMERICA AUSTRALIA = Living lungfishes = Fossilized lungfishes Figure 15.3D

  26. 15.4 Connection: Tectonic trauma imperils local life • Plate tectonics, the movements of Earth’s crustal plates, are also associated with volcanoes and earthquakes • California’s San Andreas fault is a boundarybetween two crustal plates San Andreas fault San Francisco Santa Cruz Los Angeles Figure 15.4A

  27. Example: Galápagos • But volcanic activity can also destroy life • Example: Krakatau • By forming new islands, volcanoes can create opportunities for organisms Figure 15.4B, C

  28. 15.5 Mass extinctions were followed by diversification of life-forms • At the end of the Cretaceous period, many life-forms disappeared, including the dinosaurs • These mass extinctions may have been a result of an asteroid impact or volcanic activity

  29. ? Cretaceousextinctions 90 million years ago 80 70 65 60 Figure 15.5

  30. But each was followed by a rebound in diversity • Mammals filled the void left by the dinosaurs • Every mass extinction reduced the diversity of life

  31. 15.6 Key adaptations may enable species to proliferate after mass extinctions • Adaptations that have evolved in one environmental context may be able to perform new functions when conditions change • Example: Plant species with catch basins, an adaptation to dry environments Figure 15.6

  32. 15.7 “Evo-devo:” Genes that control development play a major role in evolution • “Evo-devo” is a field that combines evolutionary and developmental biology • Major adaptations may arise rapidly if mutations occur in genes that control an organism’s early development

  33. Paedomorphosis, the retention of juvenile characteristics in the adult, seems to have played a role in human evolution Chimpanzee fetus Chimpanzee adult Figure 15.7A, B Human fetus Human adult

  34. Stephen Jay Gould argued that there was a connection between our juvenile physical traits and our long period of dependency • The youthful features of Mickey Mouse elicit affectionate, parental responses Figure 15.7C

  35. 15.8 Evolutionary trends do not mean that evolution is directed toward a goal • Evolutionary trends may reflect unequal speciation or survival of species on a branching evolutionary tree

  36. Figure 15.8

  37. 15.9 Phylogenetic trees strive to represent evolutionary history • Phylogeny is the evolutionary history of a group of organisms

  38. Cactusground finch Smalltree finch Mediumtree finch Woodpeckerfinch Mediumground finch Smallground finch Large cactusground finch Vegetarianfinch Largetree finch Mangrovefinch Greenwarbler finch Graywarbler finch Largeground finch Sharp-beakedground finch Budeaters Seedeaters Cactus flowereaters Insecteaters Ground finches Tree finches Warbler finches Common ancestor fromSouth America mainland Figure 15.9

  39. Molecular Clocks • A molecular clock compares the similarity in a certain gene to see who related more closely

  40. SYSTEMATICS AND PHYLOGENETIC BIOLOGY 15.10 Systematists classify organisms by phylogeny • Reconstructing phylogeny is part of systematics • the study of biological diversity and classification • Taxonomists assign a two-part name to each species • The first name, the genus, covers a group of related species • The second name refers to a species within a genus

  41. Taxonomy • Taxonomy – the classification of living things

  42. Classification of Living Things Carol Linnaeus – (1707-1778) Genus species Binomial nomenclature Bi – 2 nom – name nomenclature – naming Canis lupus – gray wolf Latin – universal language of scholars


  44. Hierarchy Address Planet - Earth Continent – North America Country – United States of America State - Kansas County - Rush Town - LaCrosse Street - Washington number - 400

  45. Hierarchy of Classification Kingdom Phylum Class Order Family Genus Species

  46. Remembering the order Kingdom King Phylum Phillip Class Came Order Over Family From Genus Great Species Spain