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Chapter 26

Chapter 26. The Tree of Life: An Introduction to Biological Diversity. Concept 26.1: Conditions on early Earth made the origin of life possible. Chemical and physical processes on early Earth may have produced very simple cells through a sequence of stages:

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Chapter 26

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  1. Chapter 26 The Tree of Life:An Introduction to Biological Diversity

  2. Concept 26.1: Conditions on early Earth made the origin of life possible • Chemical and physical processes on early Earth may have produced very simple cells through a sequence of stages: 1. Abiotic synthesis of small organic molecules 2. Joining of these small molecules into polymers 3. Packaging of molecules into “protobionts” 4. Origin of self-replicating molecules

  3. LE 26-2 CH4 Water vapor Electrode NH3 H2 Condenser Cold water Cooled water containing organic molecules H2O Sample for chemical analysis

  4. Video: Hydrothermal Vent Video: Tubeworms

  5. Protobionts • Protobionts are aggregates of abiotically produced molecules surrounded by a membrane or membrane-like structure Glucose-phosphate 20 mm Glucose-phosphate Phosphorylase Starch Amylase Phosphate Maltose Maltose Simple reproduction Simple metabolism

  6. Concept 26.2: The fossil record chronicles life on Earth • Fossil study opens a window into the evolution of life over billions of years • Methods of Dating Fossils: • Relative • Radiometric

  7. How Rocks and Fossils Are Dated • Sedimentary strata reveal the relative ages of fossils

  8. Index fossils are similar fossils found in the same strata in different locations Video: Grand Canyon

  9. Index Fossils

  10. The absolute ages of fossils can be determined by radiometric dating • The magnetism of rocks can provide dating information • Magnetic reversals of the magnetic poles leave their record on rocks throughout the world

  11. LE 26-7 Accumulating “daughter” isotope 1 Ratio of parent isotope to daughter isotope 2 1 Remaining “parent” isotope 4 1 8 1 16 1 2 3 4 Time (half-lives)

  12. The geologic record is divided into three eons: • Archaean • Proterozoic • Phanerozoic • boundaries marked by mass extinctions seen in the fossil record • Lesser extinctions mark boundaries of many periods within each era

  13. Phanerozoic Eon

  14. Phanerozoic Eon

  15. Millions of years ago 600 500 400 300 200 100 0 100 2,500 Number of taxonomic families 80 2,000 Permian mass extinction ) Extinction rate 60 1,500 Number of families ( Extinction rate ( 40 1,000 Cretaceous mass extinction ) 20 500 0 0 Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleogene Neogene Proterozoic eon Ceno- zoic Paleozoic Mesozoic

  16. The Permian extinction killed about 96% of marine animal species and 8 out of 27 orders of insects • It may have been caused by volcanic eruptions • The Cretaceous extinction doomed many marine and terrestrial organisms, notably the dinosaurs • It may have been caused by a large meteor impact

  17. LE 26-9 NORTH AMERICA Chicxulub crater Yucatán Peninsula

  18. LE 26-10 Ceno- zoic Meso- zoic Humans Paleozoic Land plants Animals Origin of solar system and Earth 1 4 Proterozoic Eon Archaean Eon Billions of years ago 2 3 Multicellular eukaryotes Prokaryotes Single-celled eukaryotes Atmospheric oxygen

  19. Concept 26.3: As prokaryotes evolved, they exploited and changed young Earth • The oldest known fossils are stromatolites, rocklike structures composed of many layers of bacteria and sediment • Stromatolites date back 3.5 billion years ago

  20. Photosynthesis and the Oxygen Revolution • Oxygenic photosynthesis probably evolved about 3.5 billion years ago in cyanobacteria

  21. Effects of oxygen accumulation in the atmosphere about 2.7 billion years ago: • Posed a challenge for life • Provided opportunity to gain energy from light • Allowed organisms to exploit new ecosystems

  22. The First Eukaryotes • The oldest fossils of eukaryotic cells date back 2.1 billion years

  23. Endosymbiotic Origin of Mitochondria and Plastids • The theory of endosymbiosis proposes that mitochondria and plastids were formerly small prokaryotes living within larger host cells

  24. Key evidence supporting an endosymbiotic origin of mitochondria and plastids: • Similarities in inner membrane structures and functions • Both have their own circular DNA

  25. The Colonial Connection • The first multicellular organisms were colonies, collections of autonomously replicating cells

  26. The “Cambrian Explosion” Millions of years ago 600 500 400 300 200 100 0 100 2,500 • Most of the major phyla of animals appear in the fossil record of the first 20 million years of the Cambrian period • Two animal phyla, Cnidaria and Porifera, are somewhat older, dating from the late Proterozoic Number of taxonomic families 80 2,000 Permian mass extinction ) Extinction rate 60 1,500 Number of families ( Extinction rate ( 40 1,000 Cretaceous mass extinction ) 20 500 0 0 Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleogene Neogene Proterozoic eon Ceno- zoic Paleozoic Mesozoic

  27. LE 26-17 500 Sponges Cnidarians Echinoderms Chordates Brachiopods Annelids Molluscs Arthropods Early Paleozoic era (Cambrian period) Millions of years ago 542 Late Proterozoic eon

  28. Colonization of Land by Plants, Fungi, and Animals Millions of years ago 600 500 400 300 200 100 0 100 2,500 • Plants, fungi, and animals colonized land about 500 million years ago Number of taxonomic families 80 2,000 Permian mass extinction ) Extinction rate 60 1,500 Number of families ( Extinction rate ( 40 1,000 Cretaceous mass extinction ) 20 500 0 0 Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Paleogene Neogene Proterozoic eon Ceno- zoic Paleozoic Mesozoic

  29. Continental Drift Eurasian Plate North American Plate Philippine Plate Caribbean Plate Juan de Fuca Plate Arabian Plate Indian Plate Cocos Plate South American Plate Pacific Plate Nazca Plate African Plate Australian Plate Antarctic Plate Scotia Plate

  30. LE 26-19 Volcanoes and volcanic islands Trench Oceanic ridge Subduction zone Oceanic crust Seafloor spreading

  31. LE 26-20 By about 10 million years ago, Earth’s youngest major mountain range, the Himalayas, formed as a result of India’s collision with Eurasia during the Cenozoic. The continents continue to drift today. 0 Cenozoic Eurasia North America By the end of the Mesozoic, Laurasia and Gondwana separated into the present-day continents. 65.5 Africa South America India Madagascar Australia Antarctica By the mid-Mesozoic Pangaea split into northern (Laurasia) and southern (Gondwana) landmasses. Laurasia 135 Gondwana Mesozoic Millions of years ago At the end of the Paleozoic, all of Earth’s landmasses were joined in the supercontinent Pangaea. 251 Pangaea Paleozoic

  32. Previous Taxonomic Systems • Early classification systems had two kingdoms: plants and animals • Robert Whittaker proposed five kingdoms: Monera, Protista, Plantae, Fungi, and Animalia

  33. LE 26-21 Plantae Fungi Animalia Eukaryotes Protista Prokaryotes Monera

  34. Reconstructing the Tree of Life: A Work in Progress • The five kingdom system has been replaced by three domains: Archaea, Bacteria, and Eukarya • Each domain has been split into kingdoms

  35. LE 26-22a Chapter 27 Chapter 28 Red algae Charophyceans Chlorophytes Proteobacteria Chlamydias Spirochetes Cyanobacteria Korarchaeotes Gram-positive bacteria Cercozoans, radiolarians Diplomonads, parabasalids Euglenozoans Euryarchaeotes, crenarchaeotes, nanoarchaeotes Alveolates (dinoflagellates, apicomplexans, ciliates) Stramenopiles (water molds, diatoms, golden algae, brown algae) Domain Eukarya Domain Archaea Domain Bacteria Universal ancestor

  36. LE 26-22b Chapter 29 Chapter 30 Chapter 28 Chapter 31 Chapter 32 Chapters 33, 34 Chytrids Sponges Sac fungi Club fungi Zygote fungi Angiosperms Choanoflagellates Cnidarians (jellies, coral) Arbuscular mycorrhizal fungi Seedless vascular plants (ferns) Gymnosperms Amoebozoans (amoebas, slime molds) Bryophytes (mosses, liverworts, hornworts) Bilaterally symmetrical animals (annelids, arthropods, molluscs, echinoderms, vertebrates) Plants Animals Fungi

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